HP Chapter 3 - Cell Differentiation and Homeostasis
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Questions and Answers

Why was the term 'cell' initially used by Hook to describe the structures he observed in cork?

  • Because they were filled with fluid necessary for life.
  • Because they contained moving organisms.
  • Because they resembled the rooms inhabited by monks. (correct)
  • Because they represented the basic unit of life.

What distinguishes Antonie van Leeuwenhoek's contribution to cell biology from that of Robert Hooke?

  • Leeuwenhoek developed the cell theory, while Hooke only observed cells.
  • Leeuwenhoek observed living, moving cells, while Hooke observed dead cells in cork. (correct)
  • Leeuwenhoek identified cells as the basic unit of life, while Hooke only observed dead cells.
  • Leeuwenhoek was the first to use the term 'cell,' while Hooke described their function.

The development of the cell theory, stating that cells are the basic unit of life, occurred when?

  • Simultaneously with Hooke's initial observations.
  • Approximately one year after Leeuwenhoek's observations.
  • About ten years after Hooke's initial observation.
  • In the century that followed Hooke and Leeuwenhoek's observations. (correct)

Which of the following statements best describes the primary function of cells, as understood after the development of cell theory?

<p>To house components responsible for biochemical reactions necessary for life. (C)</p> Signup and view all the answers

Considering the historical context provided, what was a key difference in understanding cells between Hooke's time and the later development of cell theory?

<p>Hooke did not realize the importance or function of cells as the basic unit of life, while later scientists did. (A)</p> Signup and view all the answers

Which of the following best describes the relationship between a cell's structure and its function?

<p>The form of a cell is optimally suited to perform its particular functions. (D)</p> Signup and view all the answers

What is the primary role of cells within the context of homeostasis?

<p>To contribute to a dynamic state of balance within parameters that are compatible with life. (A)</p> Signup and view all the answers

How does a nerve cell's structure relate to its function of communication and signal transmission?

<p>Its long, winding appendages enable communication with other cells and rapid signal transmission. (A)</p> Signup and view all the answers

What happens when a parameter within the body, such as blood pressure, moves too far out of homeostatic range?

<p>Illness, disease, or even death, can result. (C)</p> Signup and view all the answers

What is the significance of cell differentiation during development?

<p>It allows early, undifferentiated cells to become specialized in structure and function. (C)</p> Signup and view all the answers

Considering both structure and function, why are squamous skin cells suited to protect underlying tissues?

<p>Their tightly packed rows and sheets create a protective barrier. (C)</p> Signup and view all the answers

How do specialized tissues contribute to the overall function of a living organism?

<p>They work in concert to perform functions necessary for the organism. (D)</p> Signup and view all the answers

Which of the following is an example of homeostasis in the human body?

<p>The body's ability to keep its trillions of living cells moist through various mechanisms. (B)</p> Signup and view all the answers

How does the amphipathic nature of phospholipids contribute to the structure of the cell membrane?

<p>It enables the formation of a bilayer with a hydrophilic exterior and a hydrophobic core. (B)</p> Signup and view all the answers

What would happen if the cell membrane was composed primarily of hydrophobic molecules?

<p>The cell would be unable to maintain its internal environment due to the membrane's repulsion of water. (A)</p> Signup and view all the answers

Which of the following best describes the role of cholesterol within the cell membrane?

<p>To maintain membrane fluidity by preventing tight packing of phospholipids. (D)</p> Signup and view all the answers

How do the properties of the cell membrane relate to its function of regulating the passage of materials?

<p>The selective permeability allows the cell to control the entry and exit of specific substances, maintaining the internal environment. (A)</p> Signup and view all the answers

If a cell were placed in a solution containing a high concentration of hydrophobic molecules, how would the cell membrane respond?

<p>The hydrophobic molecules would integrate into the lipid tails, potentially disrupting membrane structure. (B)</p> Signup and view all the answers

Why is the back-to-back arrangement of phospholipids in the cell membrane essential for cell function?

<p>It forms a selectively permeable barrier, allowing control over what enters and exits the cell. (B)</p> Signup and view all the answers

If you increase the proportion of unsaturated fatty acids in the cell membrane, what effect would you expect it to have on membrane properties?

<p>Increase in membrane fluidity, especially at lower temperatures. (A)</p> Signup and view all the answers

How would a mutation affecting the phosphate group of phospholipids impact the cell membrane's structure?

<p>The membrane would be unable to interact effectively with aqueous environments. (A)</p> Signup and view all the answers

What is the immediate fate of a vesicle membrane after exocytosis?

<p>It becomes integrated into the cell membrane. (B)</p> Signup and view all the answers

How does the CFTR protein function in healthy individuals?

<p>It actively transports Cl- ions out of the cell. (A)</p> Signup and view all the answers

Why is the transport of Cl- ions by CFTR considered a form of active transport, despite the ions moving down their concentration gradient?

<p>Because the transport requires ATP. (D)</p> Signup and view all the answers

What direct effect does the movement of Cl- ions out of the cell have on the extracellular environment of normal lung tissue?

<p>It creates a negatively charged environment. (B)</p> Signup and view all the answers

How does the accumulation of Cl- and Na+ ions in the extracellular space contribute to the proper function of the respiratory system?

<p>It draws water into the mucus via osmosis. (A)</p> Signup and view all the answers

In a patient with cystic fibrosis, why does the mucus in the respiratory system become thick and sticky?

<p>Because the defective CFTR channel does not transport enough Cl- ions out of the cell. (A)</p> Signup and view all the answers

What role do cilia play in maintaining a healthy respiratory system?

<p>They move mucus and trapped particles away from the lungs. (B)</p> Signup and view all the answers

How does the malfunction of the CFTR protein lead to increased susceptibility to bacterial infections in CF patients?

<p>It prevents the effective removal of bacteria from the lungs. (A)</p> Signup and view all the answers

Which of the following is a primary function of exocytosis in cells, based on the information provided?

<p>Secretion of cellular products (D)</p> Signup and view all the answers

Considering the function of the CFTR protein, which tissue type would be most affected by a mutation in the CFTR gene?

<p>Epithelial tissue (B)</p> Signup and view all the answers

How does an increase in temperature primarily affect the rate of diffusion?

<p>It increases the kinetic energy of molecules, speeding up diffusion. (C)</p> Signup and view all the answers

Why does oxygen typically diffuse into cells, while carbon dioxide diffuses out?

<p>Oxygen is more concentrated outside the cell, and carbon dioxide is more concentrated inside. (C)</p> Signup and view all the answers

What is the primary difference between simple and facilitated diffusion?

<p>Simple diffusion involves movement directly across the lipid bilayer; facilitated diffusion requires transport proteins. (A)</p> Signup and view all the answers

Why can't large polar molecules easily cross the cell membrane via simple diffusion?

<p>They are repelled by the hydrophobic tails in the interior of the lipid bilayer. (C)</p> Signup and view all the answers

What conditions are necessary for osmosis to occur?

<p>A semipermeable membrane and a difference in solute concentration. (C)</p> Signup and view all the answers

How do kidneys contribute to homeostasis?

<p>By maintaining isotonic conditions in the body through blood filtration. (D)</p> Signup and view all the answers

What happens to a cell placed in a hypotonic solution?

<p>It expands and may eventually burst. (A)</p> Signup and view all the answers

Why does facilitated diffusion not require energy?

<p>It moves molecules down their concentration gradient with the help of transport proteins. (C)</p> Signup and view all the answers

What is the main driving force behind filtration?

<p>A hydrostatic pressure gradient. (B)</p> Signup and view all the answers

Which type of molecule is least likely to cross a cell membrane via simple diffusion?

<p>Large, polar molecules. (B)</p> Signup and view all the answers

During osmosis, what determines the direction of water movement across a membrane?

<p>The concentration gradient of solutes. (C)</p> Signup and view all the answers

Which of the following transport mechanisms is vital for cells to maintain proper volume and prevent bursting in a hypotonic environment?

<p>Active transport of water out of the cell. (D)</p> Signup and view all the answers

In facilitated diffusion, what role do transport proteins play?

<p>They create a channel or bind to the molecule to assist its movement down its concentration gradient. (C)</p> Signup and view all the answers

How does the body maintain homeostasis in terms of the solute concentration surrounding cells?

<p>By ensuring all cells are in an isotonic solution. (D)</p> Signup and view all the answers

Considering the properties of the cell membrane, which substance would likely require facilitated diffusion to enter a cell?

<p>Glucose (D)</p> Signup and view all the answers

What is the key characteristic of the cell membrane that allows it to control the passage of substances into and out of the cell?

<p>Its selective permeability, based on the hydrophobic interior and specific transport proteins. (C)</p> Signup and view all the answers

How do integral proteins contribute to the functionality of the cell membrane?

<p>They facilitate cell recognition and transport specific molecules across the membrane. (A)</p> Signup and view all the answers

What distinguishes channel proteins from other types of integral proteins in the cell membrane?

<p>Channel proteins facilitate the selective passage of ions or molecules. (D)</p> Signup and view all the answers

How does the glycocalyx, formed by glycoproteins and glycolipids, contribute to cell identity and interaction?

<p>By providing a unique 'sugar coating' that allows cells to be recognized; also contains receptors/enzymes. (A)</p> Signup and view all the answers

What is the role of cell recognition proteins in the function of the immune system?

<p>To mark cells as belonging to the body, preventing immune attacks. (B)</p> Signup and view all the answers

How do receptor proteins facilitate communication between the cell and its environment?

<p>By binding to specific molecules and initiating a cellular response. (A)</p> Signup and view all the answers

What is the functional consequence of a ligand binding to its receptor on a cell membrane?

<p>It induces a specific chemical reaction or change within the cell. (A)</p> Signup and view all the answers

What role do peripheral proteins play in cell membrane function, and how do they differ from integral proteins?

<p>Peripheral proteins perform specific functions and are located on the membrane surface, unlike integral proteins that are embedded. (A)</p> Signup and view all the answers

How does selective permeability of the cell membrane affect the movement of different types of molecules?

<p>It restricts the movement of polar molecules but facilitates the movement of nonpolar molecules. (D)</p> Signup and view all the answers

What determines whether a substance can pass through a cell membrane via passive transport?

<p>The concentration gradient of the substance and the membrane's permeability to it. (D)</p> Signup and view all the answers

How does the hydrophobic nature of the lipid tails in the cell membrane's phospholipid bilayer contribute to its function?

<p>It creates a barrier to water-soluble molecules, controlling what enters and exits the cell. (A)</p> Signup and view all the answers

In the context of cell membrane transport, what is the primary difference between passive and active transport?

<p>Passive transport does not require energy, whereas active transport requires energy (ATP). (C)</p> Signup and view all the answers

How does the fluidity of the cell membrane impact its overall function?

<p>It enables the movement of lipids and proteins, facilitating processes like cell signaling and transport. (D)</p> Signup and view all the answers

What is a concentration gradient, and how does it relate to the process of diffusion across the cell membrane?

<p>A concentration gradient is the difference in solute concentration across a membrane that drives diffusion. (C)</p> Signup and view all the answers

Considering the properties of diffusion, what would happen if a cell were placed in a solution with a much higher solute concentration than its cytoplasm?

<p>Water would move out of the cell, causing it to shrink. (D)</p> Signup and view all the answers

How does the sodium-potassium pump contribute to the electrical gradient in nerve cells?

<p>It moves three sodium ions out of the cell for every two potassium ions brought in, resulting in a net negative charge inside the cell. (C)</p> Signup and view all the answers

In the context of cellular transport, what is the primary distinction between active and passive transport mechanisms?

<p>Active transport requires the cell to expend energy (ATP), while passive transport does not. (D)</p> Signup and view all the answers

Which of the following best describes the mechanism of secondary active transport?

<p>It uses the electrochemical gradient created by primary active transport to power the movement of another substance. (D)</p> Signup and view all the answers

How do symporters facilitate the transport of glucose into a cell against its concentration gradient?

<p>By using the flow of sodium ions down their concentration gradient to pull glucose molecules into the cell. (D)</p> Signup and view all the answers

What is the role of antiporters in maintaining cellular homeostasis?

<p>They transport two different substances in opposite directions across the cell membrane. (C)</p> Signup and view all the answers

How does receptor-mediated endocytosis differ from phagocytosis and pinocytosis?

<p>Receptor-mediated endocytosis is highly selective for specific substances, while phagocytosis and pinocytosis are less selective. (A)</p> Signup and view all the answers

What is the primary function of exocytosis in cells?

<p>To export materials, such as proteins and hormones, out of the cell. (D)</p> Signup and view all the answers

Why is the sodium-potassium pump considered an example of primary active transport?

<p>It directly uses ATP to move sodium and potassium ions against their concentration gradients. (B)</p> Signup and view all the answers

How does filtration in the circulatory system contribute to nutrient supply for cells?

<p>It moves plasma and substances across the endothelial lining of capillaries into surrounding tissues. (D)</p> Signup and view all the answers

What would be the immediate effect on a nerve cell if the sodium-potassium pumps were suddenly disabled?

<p>The nerve cell would be unable to maintain its resting membrane potential, affecting its ability to transmit signals. (C)</p> Signup and view all the answers

Which transport mechanism is responsible for the removal of waste products from the bloodstream in the kidneys?

<p>Filtration (D)</p> Signup and view all the answers

If a cell requires a large quantity of a specific molecule from the extracellular fluid, which transport mechanism would it most likely use to efficiently import this molecule?

<p>Receptor-mediated endocytosis (D)</p> Signup and view all the answers

A cell needs to export a protein that was synthesized in the endoplasmic reticulum. Which process will it use to secrete the protein?

<p>Exocytosis (D)</p> Signup and view all the answers

How does the sodium-hydrogen antiporter help to maintain the pH of a cell's interior?

<p>By coupling the inward movement of sodium ions with the outward movement of hydrogen ions. (B)</p> Signup and view all the answers

Immune cells engulf pathogens through what process?

<p>Phagocytosis (D)</p> Signup and view all the answers

How do the organelles of the endomembrane system collaborate within a cell?

<p>By working together to synthesize, modify, and package cellular products. (A)</p> Signup and view all the answers

Why is the extensive membranous surface area of the endoplasmic reticulum (ER) crucial for its function?

<p>It allows the ER to efficiently transport, synthesize, and store materials. (C)</p> Signup and view all the answers

How is the function of a ribosome related to the information encoded in mRNA?

<p>The ribosome uses mRNA as a template to synthesize proteins. (B)</p> Signup and view all the answers

What is the primary distinction between rough ER (RER) and smooth ER (SER) in terms of their function?

<p>RER synthesizes proteins, whereas SER is involved in lipid and carbohydrate metabolism. (D)</p> Signup and view all the answers

How do the cytoplasm, cytosol, and organelles interact to maintain cell function?

<p>The cytosol suspends the organelles, providing the fluid environment for biochemical reactions within the cytoplasm. (D)</p> Signup and view all the answers

Why is the nucleus referred to as the cell's central organelle?

<p>It contains the cell's DNA, which controls the cell's functions. (A)</p> Signup and view all the answers

How does the continuous connection between the endoplasmic reticulum and the nuclear membrane benefit the cell?

<p>It provides a direct pathway for the transport of proteins and other substances. (C)</p> Signup and view all the answers

What role do ribosomes play in the rough endoplasmic reticulum (RER)?

<p>They synthesize proteins that are then modified and processed in the RER. (A)</p> Signup and view all the answers

How do microtubules facilitate the appropriate distribution of chromosomes during cell division?

<p>By setting paths along which genetic material is pulled, using ATP. (C)</p> Signup and view all the answers

What is the primary difference in function between cilia and flagella, considering their structure and purpose?

<p>Cilia are typically shorter and more numerous, used for movement of substances across the cell surface, while flagella are longer, fewer, and specialized for cell propulsion. (C)</p> Signup and view all the answers

If a drug disrupted the function of centrioles in a cell, which cellular process would be most directly affected?

<p>Formation of cilia and flagella and separation of DNA during cell division. (D)</p> Signup and view all the answers

How do actin filaments and myosin contribute to muscle contraction?

<p>Actin forms the thin filaments that are 'pulled' by myosin thick filaments to contract the cell. (A)</p> Signup and view all the answers

What role do actin filaments play in cell division?

<p>They create a cleavage furrow to split the cell into two daughter cells. (C)</p> Signup and view all the answers

In what way do intermediate filaments differ functionally from microtubules in maintaining cell structure?

<p>Intermediate filaments resist tension, while microtubules resist compression. (C)</p> Signup and view all the answers

How do intermediate filaments contribute to the structure and function of epithelial cells in the skin?

<p>They resist tension and anchor cells together, providing structural integrity when the cells are compressed and tugged in different directions. (A)</p> Signup and view all the answers

How does the structure of intermediate filaments relate to their function?

<p>Their twisted, rope-like structure provides tensile strength. (D)</p> Signup and view all the answers

What would be the likely effect on a cell if the formation of actin filaments was inhibited?

<p>Inability to form a cleavage furrow during cell division and impaired muscle contraction. (A)</p> Signup and view all the answers

Considering the functions of microtubules and intermediate filaments, which cellular process relies on both for its successful execution?

<p>Maintaining cell shape and structure. (C)</p> Signup and view all the answers

How does the extensive network of cristae within mitochondria contribute to their function?

<p>By increasing the surface area available for the enzymes and proteins involved in cellular respiration. (D)</p> Signup and view all the answers

In which of the following scenarios would you expect a cell to contain a higher amount of smooth endoplasmic reticulum (ER)?

<p>A liver cell involved in detoxifying drugs and alcohol. (A)</p> Signup and view all the answers

Which of the following best describes the coordinated functions of the rough ER, Golgi apparatus, and vesicles in protein secretion?

<p>Rough ER synthesizes and modifies proteins, Golgi sorts and packages proteins, vesicles transport proteins. (D)</p> Signup and view all the answers

How do lysosomes contribute to the process of autophagy in a cell?

<p>By fusing with vesicles containing damaged organelles and digesting their contents. (A)</p> Signup and view all the answers

Which cellular component is primarily responsible for generating ATP through cellular respiration, and why is this process essential for cell survival?

<p>The mitochondria, because it converts energy stored in nutrient molecules into usable ATP. (B)</p> Signup and view all the answers

How does the structure of the Golgi apparatus, with its distinct sides and membranous discs, support its function in modifying and packaging proteins?

<p>The distinct sides allow for the reception and shipping of products in separate vesicles. (A)</p> Signup and view all the answers

Why is the regulation of calcium ion (Ca++) concentration by the smooth ER particularly important in nerve cells?

<p>Ca++ triggers the release of neurotransmitters, enabling nerve impulse transmission. (A)</p> Signup and view all the answers

How does the process of glycosylation in the rough ER contribute to the function of proteins destined for the cell membrane or export?

<p>Glycosylation adds sugar molecules to proteins, which can aid in protein folding, stability, and cell recognition. (B)</p> Signup and view all the answers

What is the process of 'autolysis', and under what circumstances would a cell undergo this process?

<p>Autolysis is the process of a cell digesting its own structures, triggered by damage or disease. (B)</p> Signup and view all the answers

How does the presence of numerous mitochondria within muscle cells directly support their function?

<p>Mitochondria supply the ATP necessary for the energy-intensive process of muscle contraction. (B)</p> Signup and view all the answers

How does the process of phagocytosis, facilitated by lysosomes, contribute to the function of immune defense cells?

<p>Phagocytosis enables immune cells to engulf and digest pathogens, eliminating them from the body. (B)</p> Signup and view all the answers

In cells that actively secrete steroid hormones, like those in the ovaries and testes, how does the abundance of smooth ER contribute to their function?

<p>The smooth ER synthesizes the lipid-based steroid hormones. (B)</p> Signup and view all the answers

How might a bone cell's relatively low count of mitochondria compared to a nerve cell relate to the differences in their functions and energy demands?

<p>Bone cells perform fewer energy-intensive processes compared to nerve cells, requiring less ATP. (A)</p> Signup and view all the answers

How do peroxisomes contribute to cellular defense against reactive oxygen species (ROS)?

<p>By converting toxic hydrogen peroxide ($H_2O_2$) into water and oxygen. (A)</p> Signup and view all the answers

What is the likely consequence if the Golgi apparatus malfunctions, and how would this affect the function of other cellular components?

<p>Proteins would not be properly sorted and packaged, disrupting cell's ability to secrete and direct proteins to their appropriate locations. (B)</p> Signup and view all the answers

If a cell were unable to perform detoxification processes effectively, what would be the most likely long-term consequence for the cell's health and function?

<p>An accumulation of toxins, leading to cellular damage and impaired function. (B)</p> Signup and view all the answers

Which of the following represents a key distinction between the two versions of the free radical theory on aging?

<p>One proposes aging itself results from oxidative damage; the other suggests oxidative damage causes age-related diseases. (A)</p> Signup and view all the answers

In what way does the structure of microtubules relate to their function within a cell?

<p>Composed of tubulin subunits, they can rapidly assemble and disassemble, facilitating cell movement and division. (A)</p> Signup and view all the answers

How does the action of cilia in the respiratory system contribute to maintaining homeostasis?

<p>By rhythmically moving waste materials away from the lungs, preventing infection and maintaining clear airways. (B)</p> Signup and view all the answers

Which statement correctly describes the role of antioxidants in counteracting oxidative stress?

<p>Antioxidants halt the chain reactions initiated by free radicals by being oxidized themselves. (B)</p> Signup and view all the answers

Why are liver cells particularly rich in peroxisomes?

<p>To detoxify the blood by neutralizing poisons and breaking down harmful substances. (B)</p> Signup and view all the answers

How might damage to DNA caused by reactive oxygen species (ROS) lead to cancer?

<p>By promoting rapid and uncontrolled cell division due to mutations in genes that regulate the cell cycle. (D)</p> Signup and view all the answers

Which of the following accurately links a component of the cytoskeleton with its function?

<p>Microtubules: positioning organelles and forming the structural basis for cilia and flagella. (C)</p> Signup and view all the answers

What is a primary difference in function between lysosomes and peroxisomes?

<p>Lysosomes contain digestive enzymes for breaking down substances, while peroxisomes neutralize poisons and free radicals. (D)</p> Signup and view all the answers

How might calorie restriction potentially lead to increased lifespan in some organisms?

<p>By reducing oxidative stress, thus minimizing damage to cellular components. (C)</p> Signup and view all the answers

How do peroxisomes neutralize alcohol and other poisons?

<p>By transferring hydrogen atoms from the poisons to oxygen, producing hydrogen peroxide. (A)</p> Signup and view all the answers

In what way do the properties of reactive oxygen species (ROS) contribute to cellular damage?

<p>ROS oxidize other molecules by removing electrons, leading to chain reactions and damage. (D)</p> Signup and view all the answers

How are cilia and flagella similar in structure, and how does this structure contribute to their function?

<p>The core of both is made of microtubules that facilitate movement either to propel the cell or to move substances across the cell surface. (D)</p> Signup and view all the answers

Considering the function of peroxisomes, what would be the likely effect of a genetic disorder that impairs the production of catalase, an enzyme found in peroxisomes?

<p>A buildup of hydrogen peroxide ($H_2O_2$) leading to increased oxidative stress and cellular damage. (D)</p> Signup and view all the answers

What is the ultimate consequence of oxidative stress if left unchecked?

<p>Damage to cellular components, potentially leading to mutations, disease, and aging. (D)</p> Signup and view all the answers

How does the absence of a nucleus affect the functionality of mammalian red blood cells (RBCs)?

<p>It enables RBCs to carry a greater quantity of oxygen. (B)</p> Signup and view all the answers

If a cell were unable to produce pore complexes, which of the following processes would be most directly affected?

<p>The exchange of molecules between the nucleus and the cytoplasm. (D)</p> Signup and view all the answers

What role does the nucleolus play in protein synthesis?

<p>It synthesizes the RNA necessary for ribosome construction. (A)</p> Signup and view all the answers

How does the nuclear envelope regulate the movement of substances between the nucleus and the cytoplasm?

<p>It uses a system of protein channels and pores that selectively allow passage. (A)</p> Signup and view all the answers

During cell division, why is it crucial for DNA to be duplicated accurately?

<p>To ensure each daughter cell receives a full and identical complement of genetic material. (A)</p> Signup and view all the answers

What would be the most likely effect of a mutation that impairs the function of nuclear pores?

<p>Disrupted communication between the nucleus and cytoplasm. (D)</p> Signup and view all the answers

How does the structure of the nuclear envelope contribute to its function?

<p>The double membrane provides a selective barrier, and the pores facilitate controlled transport. (D)</p> Signup and view all the answers

What is the primary function of the nucleoplasm?

<p>Serves as a medium for nuclear components, containing solutes and building blocks for nucleic acids. (A)</p> Signup and view all the answers

How does the arrangement of nucleosomes contribute to the overall structure of chromatin?

<p>They create a 'beaded necklace' appearance, with DNA as the string and histones as the beads. (D)</p> Signup and view all the answers

Which of the following statements accurately describes the relationship between chromatin and chromosomes?

<p>Chromatin condenses into chromosomes during cell division to ensure safe DNA transport. (A)</p> Signup and view all the answers

What is the significance of the antiparallel arrangement of DNA strands within the double helix?

<p>It allows for complementary base pairing and efficient DNA replication. (A)</p> Signup and view all the answers

If one strand of a DNA molecule has the sequence 5'-GATTACA-3', what is the sequence of its complementary strand?

<p>5'-CTAATGT-3' (C)</p> Signup and view all the answers

What is the role of DNA polymerase during DNA replication?

<p>To add free nucleotides to the end of a chain of DNA, synthesizing a new strand base by base. (C)</p> Signup and view all the answers

Why is DNA replication described as 'semiconservative'?

<p>Because half of the original DNA molecule is conserved in each new DNA molecule. (B)</p> Signup and view all the answers

What is the potential consequence of mistakes during DNA replication, and how are they minimized?

<p>Mistakes can render a gene dysfunctional, but mechanisms such as DNA proofreading help minimize errors. (D)</p> Signup and view all the answers

What is the role of helicase in DNA replication?

<p>To untwist and separate the two strands of DNA. (A)</p> Signup and view all the answers

Which of the following cell types rarely or never divide in an adult human?

<p>Nerve cells, skeletal muscle fibers, and cardiac muscle cells. (D)</p> Signup and view all the answers

What is the primary function of DNA replication?

<p>To ensure that each new daughter cell receives a full complement of DNA identical to the original cell. (C)</p> Signup and view all the answers

How do cells ensure mistakes during DNA replication are minimized?

<p>By proofreading the newly synthesized molecule via special enzymes. (C)</p> Signup and view all the answers

Which stage of DNA replication involves DNA polymerase bringing in the correct bases to complement the template strand?

<p>Elongation (A)</p> Signup and view all the answers

During what process does chromatin condense into chromosomes?

<p>Cell division (D)</p> Signup and view all the answers

What determines the genetic code within a DNA molecule?

<p>The particular sequence of bases along the DNA molecule. (C)</p> Signup and view all the answers

Which enzyme is responsible for untwisting and separating the two strands of DNA during initiation?

<p>Helicase (B)</p> Signup and view all the answers

How does the sequence of DNA bases in a gene directly relate to protein synthesis?

<p>It dictates the order in which amino acids are assembled to form a protein. (C)</p> Signup and view all the answers

If a mutation occurred in a gene, altering a single DNA triplet, what is the most likely consequence at the protein level?

<p>The mutation would change a single amino acid in the protein sequence. (D)</p> Signup and view all the answers

What is the significance of enzymes within a cell's proteome?

<p>They accelerate biochemical reations required for cell functions. (A)</p> Signup and view all the answers

How would a cell's function be affected if gene expression were completely inhibited?

<p>The cell would be unable to produce new proteins, impairing its ability to perform its functions (A)</p> Signup and view all the answers

Which of the following cellular processes is LEAST directly dependent on the function of proteins?

<p>Lipid synthesis (C)</p> Signup and view all the answers

If a cell's ability to synthesize microtubules were impaired, which cellular function would be most immediately affected?

<p>Proper chromosome distribution during cell division (D)</p> Signup and view all the answers

Imagine a scenario where a cell is exposed to a toxin that disrupts the function of ribosomes. Which immediate effect would this have on the cell?

<p>Failure to produce proteins (D)</p> Signup and view all the answers

Distinguish the relationship between a ‘gene’ and a ‘proteome’.

<p>A gene is a functional segment of DNA that codes for a protein, while a proteome is the full complement of proteins a cell can produce. (A)</p> Signup and view all the answers

How does the structure of tRNA contribute to its role in translation?

<p>It possesses an anticodon that binds to the mRNA codon and carries a specific amino acid. (B)</p> Signup and view all the answers

What role do enzymes play during the elongation stage of translation?

<p>They assist in attaching the growing polypeptide strand to the next amino acid. (B)</p> Signup and view all the answers

What is the direct result of the stop codon being reached during translation?

<p>Translation terminates and the complete, newly synthesized protein is released. (A)</p> Signup and view all the answers

How does the presence of multiple ribosomes on a single mRNA transcript affect protein synthesis?

<p>It increases the efficiency of protein synthesis by producing multiple copies simultaneously. (D)</p> Signup and view all the answers

What is the role of GTP (Guanosine-5'-triphosphate) in the elongation stage of translation?

<p>Providing the energy required for tRNA to bind to the A site of the ribosome and for translocation. (B)</p> Signup and view all the answers

Consider a mutation that alters the anticodon loop of a tRNA molecule. What is the most likely consequence of this mutation?

<p>The tRNA will bind to a different codon on the mRNA, leading to the incorporation of an incorrect amino acid. (A)</p> Signup and view all the answers

A cell is treated with a drug that inhibits the movement of the ribosome along the mRNA. Which stage of protein synthesis would be most directly affected?

<p>Elongation. (A)</p> Signup and view all the answers

Following translation, what typically occurs to the ribosomal subunits?

<p>They separate and can participate in further rounds of translation initiation. (A)</p> Signup and view all the answers

How does the structure of mRNA facilitate its role as an intermediate between DNA and protein synthesis?

<p>Its single-stranded structure and ability to exit the nucleus allow it to carry genetic information to the cytoplasm for protein synthesis. (C)</p> Signup and view all the answers

What is the role of RNA polymerase in transcription?

<p>It adds new nucleotides to a growing strand of RNA by matching them to the coding strand of DNA. (D)</p> Signup and view all the answers

How does the presence of uracil in RNA differ from the structure of DNA, and what is its functional consequence?

<p>Uracil replaces thymine and pairs with adenine, allowing RNA to interact with ribosomes. (C)</p> Signup and view all the answers

What determines the end of transcription?

<p>A specific sequence of nucleotides, known as the terminator sequence, signals the RNA to fold and detach. (D)</p> Signup and view all the answers

Why are pre-mRNA molecules modified before leaving the nucleus?

<p>To remove non-coding regions (introns) and splice together coding regions (exons) for proper protein synthesis. (C)</p> Signup and view all the answers

What is the function of a spliceosome?

<p>To excise introns from pre-mRNA and join exons to form mature mRNA. (A)</p> Signup and view all the answers

How does alternative splicing contribute to protein diversity?

<p>By varying which coding regions (exons) are removed or included in the final mRNA, leading to different protein isoforms. (D)</p> Signup and view all the answers

What is the role of ribosomes in translation?

<p>To provide a site where mRNA can be translated into a polypeptide chain. (D)</p> Signup and view all the answers

How do rRNA and proteins collaborate within a ribosome?

<p>rRNA provides the catalytic activity for peptide bond formation, while proteins contribute to structure and stability. (D)</p> Signup and view all the answers

What is the function of tRNA in translation?

<p>To carry the correct amino acids to the ribosome based on the mRNA codon sequence. (B)</p> Signup and view all the answers

How does the anticodon of tRNA relate to the codon of mRNA?

<p>The anticodon is complementary to the mRNA codon, allowing tRNA to recognize and bind to the mRNA during translation. (C)</p> Signup and view all the answers

What would be the most likely consequence if a tRNA molecule's anticodon lost its ability to bind to its corresponding mRNA codon?

<p>The incorrect amino acid would be added to the growing polypeptide chain, potentially leading to a non-functional or altered protein. (A)</p> Signup and view all the answers

If a mutation occurred such that a spliceosome was unable to remove introns from a pre-mRNA molecule, what would be the likely effect on the resulting protein?

<p>The protein would be longer than expected and likely non-functional due to the inclusion of non-coding sequences. (B)</p> Signup and view all the answers

Considering the complementary base pairing rules, if a codon on mRNA is 'AUG,' which anticodon sequence on tRNA would recognize it?

<p>UAC (A)</p> Signup and view all the answers

If a cell were treated with a drug that inhibits the function of RNA polymerase, which process would be directly affected?

<p>Transcription (A)</p> Signup and view all the answers

How does the disruption of the homeostatic balance between proto-oncogenes and tumor suppressor genes contribute to cancer development?

<p>It can cause uncontrolled cell division and cancerous growths. (D)</p> Signup and view all the answers

What is the primary role of tumor suppressor genes in maintaining cell health?

<p>Inhibiting cell division and preventing the accumulation of mutations. (D)</p> Signup and view all the answers

How do proto-oncogenes contribute to normal cell function, and what happens when they are mutated?

<p>They regulate cell division; mutation can cause cells to divide uncontrollably. (D)</p> Signup and view all the answers

Which cellular process is most directly affected by disruptions in the balance between proto-oncogenes and tumor suppressor genes?

<p>The cell cycle. (C)</p> Signup and view all the answers

If a cell experiences a mutation that disables a key tumor suppressor gene, what is the most likely outcome?

<p>The cell will divide uncontrollably, potentially leading to tumor formation. (A)</p> Signup and view all the answers

Which of the following cell types would be LEAST likely to undergo regular cell division?

<p>Red blood cells (A)</p> Signup and view all the answers

If a somatic cell contains 46 chromosomes after mitosis but prior to cytokinesis, what is the immediate state of its chromosome number?

<p>Diploid (C)</p> Signup and view all the answers

Somatic cells are characterized by which of the following?

<p>Containing pairs of homologous chromosomes (B)</p> Signup and view all the answers

What is the primary event that characterizes the S phase of the cell cycle?

<p>Replication of DNA (D)</p> Signup and view all the answers

What is the significance of the G1 phase within the cell cycle?

<p>It is the phase of the cell cycle with the most variable duration. (C)</p> Signup and view all the answers

During which phase of the cell cycle are chromosomes duplicated?

<p>S phase (A)</p> Signup and view all the answers

If a cell has completed the S phase of the cell cycle but is prevented from entering mitosis, in which phase would the cell likely arrest?

<p>G2 phase (B)</p> Signup and view all the answers

What is the primary function of mitosis in somatic cells?

<p>Tissue repair and growth (B)</p> Signup and view all the answers

What is the primary function of cell cycle checkpoints?

<p>To ensure that each phase of the cell cycle is completed correctly before progression. (B)</p> Signup and view all the answers

How do cyclins and cyclin-dependent kinases (CDKs) regulate the cell cycle?

<p>By working together to advance or halt the cell cycle at checkpoints, based on cellular conditions. (D)</p> Signup and view all the answers

What is the role of the metaphase checkpoint in mitosis?

<p>To verify that all sister chromatids are correctly attached to microtubules before anaphase. (A)</p> Signup and view all the answers

How can the failure of cell cycle control lead to cancer?

<p>By allowing cells with damaged DNA to divide uncontrollably, leading to tumor formation. (B)</p> Signup and view all the answers

How do proto-oncogenes contribute to cell cycle regulation?

<p>By promoting cell division and growth when appropriate signals are present. (A)</p> Signup and view all the answers

What role do tumor suppressor genes play in the cell cycle?

<p>They inhibit cell division or induce apoptosis in cells with DNA damage. (C)</p> Signup and view all the answers

What is the difference between a benign and a malignant tumor?

<p>Benign tumors are easily removed and do not invade surrounding tissues, whereas malignant tumors are invasive and can cause damage. (B)</p> Signup and view all the answers

How does the concept of 'contact inhibition' relate to tumor formation?

<p>Loss of contact inhibition can cause cells to continue dividing even when surrounded by other cells, leading to tumors. (A)</p> Signup and view all the answers

What might result from a mutation that converts a proto-oncogene into an oncogene?

<p>Uncontrolled cell division, even in the absence of normal growth signals. (A)</p> Signup and view all the answers

How does a cell's 'cruise control' system relate to the regulation of the cell cycle?

<p>It is a metaphor for the balanced interaction of 'stop' and 'go' signals that maintain proper cell division. (B)</p> Signup and view all the answers

How do environmental factors contribute to the development of cancer?

<p>They can damage DNA and disrupt the function of cell cycle control signals. (C)</p> Signup and view all the answers

If a cell with significant DNA damage fails to undergo apoptosis, what might be the consequence?

<p>The cell might continue to divide with the damaged DNA, potentially leading to cancer. (D)</p> Signup and view all the answers

How does the immune system contribute to preventing cancer?

<p>By detecting and destroying cells that have become cancerous. (D)</p> Signup and view all the answers

What is the significance of maintaining a balance between proto-oncogene and tumor suppressor gene activity?

<p>It ensures that cells only divide when necessary and that damaged cells are properly managed. (B)</p> Signup and view all the answers

Why is precise cell cycle regulation critical for maintaining the health of an organism?

<p>Because it ensures that cells divide only when appropriate and that errors are corrected, preventing diseases like cancer. (D)</p> Signup and view all the answers

What is the significance of the S phase in the cell cycle?

<p>The amount of DNA within the cell precisely doubles through DNA synthesis. (B)</p> Signup and view all the answers

What structure is directly responsible for attaching sister chromatids to each other?

<p>Centromere (A)</p> Signup and view all the answers

How does the number of chromatids in a human cell change during the S phase?

<p>It doubles from 46 to 92. (B)</p> Signup and view all the answers

What is the main event that characterizes anaphase?

<p>The separation of sister chromatids into individual chromosomes and their movement to opposite poles. (A)</p> Signup and view all the answers

Which event typically occurs during telophase?

<p>Two new daughter nuclei form, and chromosomes return to loosely packed chromatin. (D)</p> Signup and view all the answers

What role do microfilaments play during cytokinesis?

<p>They make up the cleavage furrow that pinches the cell into two. (B)</p> Signup and view all the answers

What would result if a cell completed mitosis but failed to undergo cytokinesis?

<p>A larger cell with more than one nucleus would form (C)</p> Signup and view all the answers

Which of the following best describes the G0 phase?

<p>A resting phase where cells have temporarily or permanently stopped dividing. (D)</p> Signup and view all the answers

What is the role of the kinetochore during mitosis?

<p>It is the point of attachment between the mitotic spindle and the sister chromatids. (A)</p> Signup and view all the answers

How do centrosomes contribute to the process of mitosis?

<p>They serve as origin points for microtubule growth and form the mitotic spindle. (C)</p> Signup and view all the answers

Which event marks the beginning of prometaphase?

<p>Invasion of the nuclear area by microtubules after the nuclear membrane disintegrates (D)</p> Signup and view all the answers

How do sister chromatids differ from homologous chromosomes?

<p>Sister chromatids are an original chromosome and its exact copy attached during mitosis, while homologous chromosomes are two paired chromosomes inherited separately. (C)</p> Signup and view all the answers

Which cellular structure disappears during prophase?

<p>Nucleolus (C)</p> Signup and view all the answers

What is the composition of the cleavage furrow that forms during cytokinesis?

<p>Microfilaments (C)</p> Signup and view all the answers

Which event takes place during metaphase?

<p>Sister chromatids line up along a linear plane in the middle of the cell. (B)</p> Signup and view all the answers

During human development, how do totipotent stem cells differ functionally from pluripotent stem cells?

<p>Totipotent stem cells can support the full development of an organism, whereas pluripotent stem cells cannot. (A)</p> Signup and view all the answers

What characteristic distinguishes stem cells from other cell types in the body?

<p>Stem cells can divide without limit and differentiate into specialized cells. (A)</p> Signup and view all the answers

How does the process of cellular differentiation contribute to the development of a complex organism?

<p>It allows cells to assume distinct morphologies and functions. (A)</p> Signup and view all the answers

What is the relationship between multipotent and oligopotent stem cells?

<p>Oligopotent cells are more specialized than multipotent cells. (B)</p> Signup and view all the answers

How does a unipotent cell differ from a totipotent stem cell?

<p>A unipotent cell is fully specialized and can only reproduce its own cell type, whereas a totipotent cell can differentiate into all cell types needed to create an organism. (A)</p> Signup and view all the answers

In what way are adult stem cells significant for tissue maintenance and repair?

<p>They can replace damaged or lost cells within specific tissues. (B)</p> Signup and view all the answers

What factor determines the specific cell types into which different stem cells can differentiate?

<p>The developmental stage of the organism and specific conditions. (D)</p> Signup and view all the answers

How does the presence of epithelial stem cells contribute to the function of the skin?

<p>They differentiate into keratinocytes to maintain the epidermal barrier. (D)</p> Signup and view all the answers

What is the key distinction between the roles of hematopoietic stem cells and mesenchymal stem cells found in adult bone marrow?

<p>Hematopoietic stem cells differentiate into blood cells, while mesenchymal stem cells differentiate into muscle and connective tissues. (B)</p> Signup and view all the answers

How do transcription factors influence cell differentiation?

<p>They control which genes are transcribed into mRNA, effectively turning genes 'on' or 'off'. (C)</p> Signup and view all the answers

What is the primary advantage of using induced pluripotent stem cells (iPSCs) in cell-based therapy compared to embryonic stem cells (hESCs)?

<p>iPSCs are less likely to trigger an immune response in the patient. (A)</p> Signup and view all the answers

Why are adult stem cells considered multipotent rather than pluripotent?

<p>Adult stem cells can only differentiate into a limited range of cell types, whereas pluripotent stem cells can differentiate into nearly any cell type. (B)</p> Signup and view all the answers

How does cell differentiation relate to the genetic content of a cell?

<p>Cells contain the same DNA, but only express the genes relevant to their specific function. (B)</p> Signup and view all the answers

Which of the following statements best describes the function of adult stem cells within a tissue?

<p>They continuously divide and differentiate to repair and renew specialized cells within the tissue. (C)</p> Signup and view all the answers

What is a major obstacle in the application of embryonic stem cells (hESCs) for cell-based therapy?

<p>hESCs are likely to trigger an immune rejection response in the patient. (B)</p> Signup and view all the answers

How do researchers induce stem cells to differentiate into specialized cells in a laboratory setting?

<p>By changing the physical and chemical conditions of growth. (A)</p> Signup and view all the answers

Why is the study of stem cells considered promising for treating diseases like diabetes and heart disease?

<p>Stem cells can be differentiated into cells that replace damaged or destroyed cells in these diseases. (A)</p> Signup and view all the answers

What is the main purpose of 'banking' cord blood or deciduous teeth?

<p>To preserve a source of multipotent stem cells for potential future use. (A)</p> Signup and view all the answers

Why is maintaining calcium homeostasis crucial for overall physiological function?

<p>Calcium plays a critical role in various processes, including nerve function, muscle contraction, and enzyme activity. (C)</p> Signup and view all the answers

How does the skeletal system contribute to calcium homeostasis?

<p>It serves as a calcium reservoir, storing and releasing calcium ions as needed to maintain blood calcium levels. (C)</p> Signup and view all the answers

Which of the following is a key difference in the roles of osteoblasts and osteoclasts in calcium homeostasis?

<p>Osteoclasts break down bone to release calcium, while osteoblasts use calcium to build new bone. (A)</p> Signup and view all the answers

How do hormones such as parathyroid hormone (PTH) and calcitonin regulate calcium homeostasis?

<p>PTH raises blood calcium levels by promoting calcium release from bone, while calcitonin lowers blood calcium levels by inhibiting bone resorption. (C)</p> Signup and view all the answers

How do the kidneys contribute to calcium homeostasis in the body?

<p>The kidneys regulate calcium excretion in urine and can reabsorb calcium back into the bloodstream under the influence of hormones like PTH. (B)</p> Signup and view all the answers

How would disruption of the rough ER's function most directly affect a cell?

<p>Impeding the synthesis of proteins destined for secretion or insertion into membranes. (B)</p> Signup and view all the answers

Considering their roles in maintaining cell structure, which of these cytoskeleton components is most like the steel beams in a building?

<p>Intermediate filaments (D)</p> Signup and view all the answers

If a cell were unable to produce sufficient ATP, which of the following processes would be most immediately affected?

<p>Active transport of ions against their concentration gradients. (B)</p> Signup and view all the answers

How would the structure of the nucleolus be affected if ribosome production was inhibited?

<p>The nucleolus would likely decrease in size and activity. (B)</p> Signup and view all the answers

A coding region of a gene in a DNA molecule has the sequence 5'-GATTACA-3'. What would be the corresponding sequence in the transcribed mRNA?

<p>5'-GUAAUCT-3' (A)</p> Signup and view all the answers

If a cell began to divide uncontrollably due to a mutation, in which phase of the cell cycle would a mutation in a cyclin protein likely have its most direct effect?

<p>M phase (D)</p> Signup and view all the answers

Which of the following sequences correctly represents the arrangement of stem cell potency from the greatest to the least?

<p>Pleuripotency, multipotency, oligopotency, unipotency (C)</p> Signup and view all the answers

During DNA replication, consider a mutation that impairs the function of DNA ligase. What would be the most likely consequence of this mutation?

<p>Incomplete formation of the lagging strand due to discontinuous synthesis. (B)</p> Signup and view all the answers

How does the extensive network of the endoplasmic reticulum (ER) and the folding of the mitochondrial inner membrane (cristae) directly support their respective functions?

<p>Both increase surface area to enhance the efficiency of biochemical reactions. (B)</p> Signup and view all the answers

If sister chromatids failed to properly attach to microtubules during metaphase, what would be the most likely outcome if anaphase were to proceed?

<p>One daughter cell would receive an extra chromosome, while the other would lack a chromosome. (B)</p> Signup and view all the answers

How do cyclin-dependent kinases (CDKs) and cyclins interact to regulate the cell cycle, and what is the consequence of this interaction?

<p>Cyclins activate CDKs, which then phosphorylate target proteins to drive the cell cycle forward. Then, cyclin degradation deactivates CDK. (A)</p> Signup and view all the answers

Why is DNA replication described as 'semiconservative,' and what would be the immediate consequence if this process were entirely conservative?

<p>Because each new DNA molecule contains one original and one newly synthesized strand. If conservative, new DNA would consist of two new strands, separate from the original. (D)</p> Signup and view all the answers

Considering the roles of transcription factors, what would happen if a specific transcription factor, essential for the production of a digestive enzyme in pancreatic cells, were mutated and rendered non-functional?

<p>The pancreatic cells would be unable to produce the digestive enzyme, impairing digestion. (A)</p> Signup and view all the answers

Flashcards

What is a 'cell'?

The term coined by Robert Hooke to describe the small compartments he observed in cork, resembling monks' rooms.

Who was Antonie van Leeuwenhoek?

He was the first to observe living and moving cells under a microscope.

What is the cell theory?

The idea that cells are the fundamental units of life, containing components for biochemical reactions necessary for organismal function.

What are cell compartments?

Small, fluid-filled enclosures within a cell that house components crucial for various biochemical reactions necessary for an organism's survival.

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What is a 'prototypical cell'?

A representation of a generalized cell that includes major components and functions common to many cells.

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Undifferentiated Cells

Early cells that can differentiate into specialized cells.

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Cell Differentiation

Cells becoming specialized in structure and function.

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Cellular Cooperation

Tissues, organs, and systems working together.

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Squamous Cell

A flat, protective cell, like in skin.

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Form Follows Function

Structure is matched for specific tasks.

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Homeostasis

Maintaining a stable internal environment.

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Dynamic Equilibrium

A state of balance within the body.

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Cell

The basic unit of life.

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Cell Membrane

The outer boundary separating a cell's interior from its external environment, providing protection and regulating passage of materials.

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Phospholipid Bilayer

A two-layered structure of phospholipids that forms the basic framework of the cell membrane.

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Phospholipid

A type of lipid molecule with a polar, water-attracting phosphate head and two nonpolar, water-repelling fatty acid tails.

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Hydrophilic

Attracted to water due to its polar nature.

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Hydrophobic

Repelled by water due to its nonpolar nature.

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Amphipathic Molecule

Molecules possessing both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions.

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Intracellular Fluid (ICF)

The fluid located inside a cell, primarily water-based, in which organelles and other cellular components are suspended

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Extracellular Fluid

The fluid outside the cell.

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Extracellular Fluid (ECF)

Fluid outside of cells; the body's external environment for cells.

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Interstitial Fluid (IF)

ECF specifically not contained within blood vessels; fluid between cells.

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Membrane Fluidity

The characteristic of a membrane that allows lipids and proteins to move, not rigidly locked.

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Integral Proteins

Proteins embedded within the cell membrane; often span the entire membrane.

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Channel Protein

An integral protein that allows specific ions or molecules to pass through the membrane.

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Cell Recognition Proteins

Integral proteins that mark a cell's identity for recognition by other cells.

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Receptor

A recognition protein that binds to a specific molecule, triggering a cellular response.

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Ligand

The specific molecule that binds to and activates a receptor.

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Glycoprotein

A protein with carbohydrate molecules attached, extending into the extracellular matrix; aids in cell recognition.

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Glycocalyx

A coating around the cell formed from glycoproteins and carbohydrates; involved in cell recognition and binding.

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Peripheral Proteins

Proteins found on the surface of the lipid bilayer or attached to integral proteins; perform specific functions for the cell.

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Selective Permeability

The cell membrane's ability to control which substances pass into or out of the cell.

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Passive Transport

Movement across the cell membrane without using cellular energy.

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Active Transport

Movement across the cell membrane using energy (ATP).

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Concentration Gradient

The difference in concentration of a substance across a space.

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What is diffusion?

The process where molecules move from an area of high concentration to an area of low concentration.

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How does temperature affect diffusion?

Diffusion rate increases with temperature because molecules have more kinetic energy.

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What is passive transport?

Moving down a concentration gradient across a membrane without cell energy expenditure.

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What is simple diffusion?

Movement of substances like gases across a cell membrane from high to low concentration.

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What is facilitated diffusion?

Diffusion across a cell membrane that requires the help of membrane proteins.

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What is osmosis?

Diffusion of water across a semipermeable membrane.

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What are isotonic solutions?

Solutions with the same solute concentration.

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What is a hypertonic solution?

A solution with a higher solute concentration.

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What is a hypotonic solution?

A solution with a lower solute concentration.

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Why is tonicity important?

Maintaining stable solute concentrations in and out of cells.

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What is filtration?

Using pressure to force fluids and solutes across a membrane.

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What is hydrostatic pressure?

The pressure that drives fluid and solutes in filtration.

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Why does O2 diffuse into cells?

Oxygen enters cells because it's more concentrated outside.

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Why does CO2 diffuse out of cells?

Carbon dioxide exits cells because it's more concentrated inside.

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How do kidneys aid homeostasis?

The kidneys help maintain isotonic conditions by managing water and solute balance.

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Filtration in the Circulatory System

Movement of plasma and substances across capillary linings into tissues.

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Pumps

Membrane proteins that use ATP to move substances against their concentration gradients.

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Sodium-Potassium Pump

An ion pump that transports sodium out and potassium into the cell.

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Electrical Gradient

Difference in electrical charge across a space.

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Secondary Active Transport

Active transport that indirectly powers the transport of other substances.

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Symporters

Secondary active transporters that move two substances in the same direction.

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Antiporters

Secondary active transporters moving substances in opposite directions.

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Endocytosis

Cell ingesting material by enveloping it in a portion of its membrane.

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Vesicle

Membranous sac used to transport substances inside cells.

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Phagocytosis

Endocytosis of large particles.

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Pinocytosis

Endocytosis of fluid containing dissolved substances.

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Receptor-Mediated Endocytosis

Endocytosis via receptors specific for a certain substance.

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Exocytosis

Cell exporting material using vesicular transport.

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Cystic Fibrosis (CF)

A genetic disorder caused by a mutation in the CFTR gene, leading to thick mucus and lung infections.

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CFTR Protein

A membrane protein that transports chloride ions (Cl-) out of the cell, crucial for maintaining proper mucus consistency.

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CFTR and Active Transport

A form of active transport where the CFTR protein uses ATP to transport Cl- ions down their concentration gradient.

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Cilia

Hair-like appendages on cells that move mucus and trapped particles away from the lungs.

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Mucus

A secreted substance in the respiratory system that traps dust, bacteria, and debris.

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Osmosis

The movement of water across a semipermeable membrane from an area of high water concentration to low water concentration.

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Extracellular Space

The fluid outside the cell, containing ions like Na+ and Cl- that influence water movement.

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Water Concentration Gradient in Lungs

The concentration gradient that attracts water into the mucus, thinning it for effective removal from the respiratory system.

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CF Mucus

In cystic fibrosis, the mucus becomes thick and sticky due to the lack of Cl- transport, preventing effective removal of debris and bacteria.

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Cytoplasmic Compartment

Internal compartment of living cells containing cytosol and organelles.

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Cytosol

Jelly-like substance within the cell where biochemical reactions occur.

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Organelle

Membrane-enclosed bodies within eukaryotic cells performing specific functions.

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Nucleus

Cell's control center containing DNA.

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Endomembrane System

System of organelles working together to produce, package, and export cellular products.

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Endoplasmic Reticulum (ER)

System of channels continuous with the nuclear membrane for transport, synthesis, and storage.

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Rough ER (RER)

ER dotted with ribosomes, involved in protein synthesis.

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Ribosome

Organelle that serves as the site of protein synthesis.

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Flagellum

A larger appendage specialized for cell locomotion.

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Human Sperm Cell

The only flagellated cell in humans.

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Microtubules

Hollow tubes that serve as tracks for moving genetic material during cell division.

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Centrioles

Structures that serve as the origin point for microtubules.

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Tubulin

The protein subunits composing microtubules.

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Microfilaments

Thinner cytoskeletal filaments composed of actin.

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Actin

Protein that forms chains in microfilaments.

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Intermediate Filaments

Cytoskeletal filaments that resist tension and maintain cell shape.

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Keratin

Protein subunits in intermediate filaments that are wound together.

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Smooth Endoplasmic Reticulum

Synthesizes lipids, phospholipids, and steroid hormones; regulates Ca++ concentration; metabolizes carbohydrates; detoxifies toxins.

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Rough Endoplasmic Reticulum

Synthesizes and modifies proteins for the cell membrane or export, often glycosylating them.

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Glycosylation

The addition of sugars to a protein in the rough ER.

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Golgi Apparatus

Sorts, modifies, and ships products from the rough ER; produces lysosomes.

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Lysosome

Organelle containing digestive enzymes for breaking down unneeded cellular components.

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Autophagy

Process of a cell digesting its own structures.

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Autolysis

Enzymes from lysosomes digesting and killing a cell.

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Apoptosis

Controlled cell death.

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Cell's Important Functions

Nutrient intake, energy conversion, detoxification.

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Hepatocytes

Cells in the liver that detoxify toxins.

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Mitochondrion

"Energy transformer" of a cell; site of cellular respiration; produces ATP.

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Cristae

Inner membrane folds of a mitochondrion; increase surface area for cellular respiration.

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Adenosine Triphosphate (ATP)

Energy-carrying molecule used by cells to power biochemical reactions.

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Cellular Respiration

Biochemical reactions that convert energy stored in nutrients into ATP, requiring oxygen.

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What is a Peroxisome?

A membrane-bound organelle that contains enzymes for lipid metabolism & detoxification, it produces hydrogen peroxide (H2O2).

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Peroxisome Function

The transfer of hydrogen atoms from molecules to oxygen, producing H2O2.

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Reactive Oxygen Species (ROS)

Highly reactive byproducts of cellular processes that can cause damage.

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Free Radicals

Molecules with unpaired electrons that can damage cells.

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Oxidative Stress

Damage to cellular components caused by reactive oxygen species.

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Mutation

A change in the nucleotide sequence of a gene.

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Antioxidants

Substances that neutralize free radicals, preventing oxidative damage.

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Free Radical Theory of Aging

Suggests that accumulated cellular damage from oxidative stress contributes to the effects of aging

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Calorie-Restriction

Moderately restricting caloric intake to potentially increase lifespan.

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Cytoskeleton

A network of fibrous proteins that provide structural support, motility, reproduction, and transport within the cell.

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Liver's Role in Detoxification

Organ responsible for detoxifying blood, containing many peroxisomes.

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Catalase

Enzymes within peroxisomes that convert toxic hydrogen peroxide (H2O2) into water and oxygen.

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Ciliary Motion

The process by which cilia move waste materials such as dust, mucus, and bacteria upward through the airways, away from the lungs and toward the mouth

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What is the Nucleus?

The control center of the cell that stores genetic instructions for protein manufacturing.

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What is a multinucleated cell?

Having more than one nucleus in a cell.

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What are Nuclear Pores?

Tiny passageways in the nuclear envelope for transport between the nucleus and cytoplasm.

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What is Nucleoplasm?

A gel-like substance inside the nuclear envelope containing solutes and building blocks of nucleic acids.

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What is a Nucleolus?

The region in the nucleus responsible for manufacturing RNA for ribosome construction.

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What is the Nuclear Envelope?

A double-layered membrane surrounding the nucleus.

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What are Molecular Messengers?

A molecular messenger that translates information from DNA to the cell.

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What is DNA Replication?

The process of creating a duplicate copy of DNA.

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Chromatin

DNA and proteins that make up the genetic material within the nucleus.

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Nucleosome

A complex of DNA wrapped around histone proteins.

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Chromosome

Condensed form of chromatin, composed of DNA and proteins, visible during cell division.

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DNA Replication

The copying of DNA before cell division.

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Helicase

Enzyme that unwinds and separates DNA strands during replication.

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DNA Polymerase

Enzyme that adds complementary nucleotides to synthesize a new DNA strand.

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Genome

The entire complement of an organism's DNA.

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Semiconservative Replication

A process where each new DNA molecule contains one original and one new strand.

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DNA Proofreading

The process of checking and correcting mistakes during DNA replication.

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DNA Double Helix

A double-stranded molecule resembling a twisted ladder.

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Antiparallel (DNA)

The two DNA strands run in opposite directions.

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DNA Bases

Adenine, Thymine, Cytosine, and Guanine.

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Base Pairing Rule

A binds with T, and C binds with G.

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DNA Backbone

Alternating sugar and phosphate groups forming the sides of the DNA ladder.

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Genetic Code

The sequence of bases along the DNA molecule.

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What is DNA's "blueprint"?

A molecule containing the information to build proteins.

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What is a proteome?

The cell's complete set of proteins.

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What is a gene?

A segment of DNA containing the code to construct a particular protein.

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What is gene expression?

The process of turning the DNA code into a functional protein.

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What is a triplet?

A sequence of three DNA bases that codes for a specific amino acid.

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What triplet codes for valine?

CAC

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How is DNA code turned into a protein?

A two-step process, DNA -> RNA -> Protein.

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What dictates cell structure and function?

Transforming information coded in a gene to a final gene product.

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Translation

The process where tRNA reads mRNA codons and delivers corresponding amino acids.

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Initiation (Translation)

The stage where a ribosome binds to mRNA.

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Elongation (Translation)

The stage involving tRNA anticodon recognition of the mRNA codon, adding amino acids to the growing polypeptide chain.

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Termination (Translation)

The stage where the final codon signals the release of the newly synthesized protein.

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mRNA Codon

A sequence of three nucleotides in mRNA that specifies a particular amino acid or stop signal during translation.

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tRNA Anticodon

A sequence of three nucleotides in tRNA that is complementary to an mRNA codon, ensuring the correct amino acid is added to the polypeptide chain.

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Polyribosome

A string of ribosomes translating a single mRNA strand simultaneously, enhancing protein synthesis efficiency.

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Transcription

The process of creating mRNA from DNA, which then informs protein synthesis.

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mRNA (messenger RNA)

A single-stranded nucleic acid that carries genetic code from DNA in the nucleus to the cytoplasm for protein synthesis.

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Promoter (in transcription)

The region on DNA that initiates transcription of a particular gene.

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Terminator Sequence

A sequence of nucleotides that signals the end of transcription, causing RNA to detach.

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Introns

Non-coding regions of pre-mRNA that are removed during splicing.

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Exons

Coding regions of mRNA that remain after splicing and are translated into protein.

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Spliceosome

Complex that splices pre-mRNA by removing introns and joining exons.

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Codon

A three-base sequence of mRNA that codes for a specific amino acid.

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rRNA (ribosomal RNA)

Type of RNA that, along with proteins, forms ribosomes.

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tRNA (transfer RNA)

Type of RNA that carries specific amino acids to the ribosome during translation.

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Anticodon

A three-base sequence on tRNA that complements an mRNA codon, ensuring correct amino acid placement.

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Pre-mRNA

The initial mRNA molecule that is transcribed from DNA, containing both introns and exons.

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Template Strand (DNA)

The strand of DNA that serves as the template for RNA synthesis during transcription.

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Proto-oncogenes

Genes that promote normal cell growth and division. When mutated, they can become oncogenes.

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Tumor Suppressor Genes

Genes that regulate cell division and prevent uncontrolled growth. Loss of function can lead to cancer.

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Cell Cycle

The tightly controlled process of cell growth and division, ensuring healthy cell replication.

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Aberrant Cell Division

A disruption of balance between proto-oncogenes and tumor suppressor genes, leading to uncontrolled cell division.

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Cancerous Growths

Abnormal masses of cells resulting from uncontrolled cell division.

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Somatic Cells

Cells that make up the body, excluding germ cells (sperm and egg).

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Homologous Pair

Two copies of a single chromosome found in each somatic cell; one from each parent.

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Diploidy

Having two sets of chromosomes, one from each parent (2n).

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Interphase

The period of the cell cycle during which the cell is not actively dividing.

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Mitosis

Division of the genetic material (nucleus) in a cell.

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Cytokinesis

Division of the cytoplasm into two distinct cells.

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G1 Phase

A growth phase where the cell grows and carries out normal functions.

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Cell Cycle Control Triggers

Signals that regulate the cell's progression; can be internal or external.

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Cell Cycle Checkpoint

A point where the cell cycle can either proceed or halt, based on internal conditions.

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Cyclin

A primary class of molecules that regulate the cell cycle.

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Cyclin-Dependent Kinase (CDK)

Molecules that work with cyclins to control cell cycle progression.

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G1 Checkpoint

Ensures the cell is ready for DNA synthesis.

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G2 Checkpoint

Ensures the cell is prepared for mitosis.

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Metaphase Checkpoint

Ensures sister chromatids are properly attached before separation.

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Cancer

Abnormal cells multiplying continuously.

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Benign Tumor

A tumor that does not pose a threat to surrounding tissues.

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Malignant Tumor

A tumor capable of causing damage; diagnosed as cancer.

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Oncogenes

Proto-oncogenes that have become mutated and promote excessive cell division.

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Oncoproteins

Proteins produced by oncogenes that stimulate cell division even when undesirable.

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Contact Inhibition

Normal cells stop dividing when they contact neighboring cells.

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Sister Chromatids

Two identical copies of a chromosome, attached at the centromere.

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Centromere

Structure attaching one sister chromatid to another.

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Prophase

First stage of mitosis; chromatin condenses into visible chromosomes.

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Centrosome

A pair of centrioles together.

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Mitotic Spindle

Structure of centrosomes and microtubules involved in mitosis.

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Kinetochore

Protein structure on the centromere where microtubules attach.

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Metaphase

Second stage of mitosis; sister chromatids align in the middle of the cell.

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Metaphase Plate

The plane in the middle of the spindle where sister chromatids align.

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Anaphase

Third stage of mitosis; sister chromatids separate and move to opposite poles.

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Telophase

Final stage of mitosis; new nuclei form around separated chromosomes.

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Cleavage Furrow

A contractile band that pinches the cell in half during cytokinesis.

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Cellular Differentiation

Process where unspecialized cells become specialized with distinct functions.

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Stem Cell

An unspecialized cell that can divide and differentiate into specialized cells.

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Totipotent Stem Cell

Stem cells with the potential to differentiate into any cell type needed for organism development.

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Pluripotent Stem Cell

Stem cell that can differentiate into any human tissue but cannot support full organism development.

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Multipotent Stem Cell

Stem cell with potential to differentiate into different cell types within a specific lineage.

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Oligopotent Stem Cell

Stem cell limited to becoming one of a few different cell types.

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Unipotent Cell

Fully specialized cell that can only reproduce its own specific cell type.

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Epithelial Stem Cell

Stem cells found in the epidermis that produce keratinocytes.

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Hematopoietic Stem Cells

Stem cells that give rise to red blood cells, white blood cells, and platelets.

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Endothelial Stem Cells

Stem cells that give rise to the endothelial cell types lining blood and lymph vessels.

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Mesenchymal Stem Cells

Stem cells that give rise to different types of muscle cells.

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Transcription Factors

Proteins that bind to specific genes on DNA to control their transcription.

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Human Embryonic Stem Cells (hESCs)

Stem cells that can differentiate into many cell types, derived from embryos.

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Induced Pluripotent Stem Cells (iPSCs)

Multipotent adult cells reprogrammed to act like embryonic stem cells.

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Cell-Based Therapy

Treatment using stem cells to repair or replace damaged cells/tissues.

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Genetic Expression

The unique activation and silencing of genes in a cell.

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Calcium Homeostasis

Maintenance of stable levels of calcium in the body.

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Skeletal System Role

The hard tissue of the skeletal system that stores most of the body's calcium.

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Bone Resorption

The process by which bone tissue is broken down and calcium is released into the bloodstream.

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Parathyroid Hormone (PTH)

A hormone that increases calcium levels in the blood, mainly through bone resorption.

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Calcitonin

A hormone that lowers calcium levels in the blood, primarily by promoting calcium deposition in bones.

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Ion Channels

Proteins embedded within the cell membrane that allow specific ions to pass through.

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Diffusion

The movement of substances from an area of high concentration to an area of low concentration.

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Complementary DNA Sequence

The sequence of bases that would pair with GCTTATAT on a DNA molecule (AAGAATATA).

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Unipotent Stem Cell

A cell that can differentiate into only one type of cell.

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Diffusion Through Lipid Bilayer

Small, nonpolar molecules like oxygen and carbon dioxide, due to the hydrophobic nature of the lipid bilayer.

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Receptor-Mediated Endocytosis Selectivity

It uses specific receptors to bind and internalize only targeted substances, while phagocytosis and pinocytosis are less selective.

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Commonality of Passive Processes

They all move substances down a gradient (concentration, pressure, or charge) without requiring cellular energy. They differ in the type of substance moved and the driving force.

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ER, Mitochondria, and Golgi Structure-Function

The extensive folding of these organelles increases their surface area allowing for more efficient biochemical reactions.

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Lysosomes vs. Peroxisomes

Both are organelles containing enzymes. Lysosomes digest cellular waste, while peroxisomes detoxify substances and break down fatty acids.

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Study Notes

  • Materials that can easily diffuse through the lipid bilayer are typically small, nonpolar molecules due to the hydrophobic nature of the lipid tails.
  • Receptor-mediated endocytosis is more selective than phagocytosis or pinocytosis because it relies on specific receptors on the cell surface that bind to particular target molecules.
  • Osmosis, diffusion, filtration, and the movement of ions away from like charges all involve the movement of substances down a gradient (concentration, pressure, or electrical).
  • They differ in the type of gradient and the substances involved.
  • The ER's extensive network of membranes increases surface area for protein and lipid synthesis.
  • Mitochondria's folded inner membrane (cristae) increases surface area for ATP production.
  • The Golgi apparatus' flattened sacs (cisternae) facilitate the processing and packaging of proteins.
  • Lysosomes and peroxisomes are both membrane-bound organelles that contain enzymes.
  • Both function in breaking down materials within the cell.
  • Lysosomes contain enzymes that digest cellular waste and debris, while peroxisomes contain enzymes that detoxify harmful substances like alcohol and also break down fatty acids.
  • DNA replication is said to be "semiconservative" because each new DNA molecule consists of one original (template) strand and one newly synthesized strand.
  • DNA replication must take place before cell division to ensure that each daughter cell receives a complete and identical copy of the genetic material.
  • If cell division occurred without DNA replication, or with incomplete replication, the daughter cells would have missing or incomplete genetic information, leading to cell death or dysfunction.
  • Transcription is the process of synthesizing RNA from a DNA template, while translation is the process of synthesizing a protein from an RNA template.
  • Transcription occurs in the nucleus, while translation occurs in the cytoplasm.
  • Transcription produces RNA, while translation produces proteins.
  • If anaphase proceeded even though the sister chromatids were not properly attached to their respective microtubules and lined up at the metaphase plate, the resulting daughter cells would have an unequal number of chromosomes (aneuploidy).
  • Cyclins and cyclin-dependent kinases (CDKs) are regulatory proteins that control the cell cycle.
  • Cyclins bind to and activate CDKs, which then phosphorylate target proteins that drive the cell cycle forward.
  • A transcription factor ultimately determines whether or not a protein will be present in a given cell by regulating the transcription of the gene that encodes that protein.
  • Transcription factors bind to specific DNA sequences and either promote or inhibit the transcription of a gene.
  • The therapeutic use of embryonic stem cells can present problems because of ethical concerns surrounding the destruction of embryos and the risk of immune rejection of the transplanted cells.
  • Ion channels exemplify proteins embedded within the cell membrane.
  • Diffusion moves substances down their concentration gradient.
  • Diffusion relates to filtration, as endocytosis relates to pinocytosis.
  • Cytoplasm is to cytosol as a swimming pool containing chlorine and flotation toys relates to water.
  • The rough ER is named for the ribosomes associated with it.
  • A function of the rough ER is protein synthesis.
  • A common feature to all three cytoskeleton components is that they are polymers.
  • Mitochondria produce large quantities of ATP when glucose and oxygen are available.
  • The nucleolus contains ribosomal RNA.
  • The DNA sequence CGAATATA is complementary to GCTTATAT.
  • From least to most complex: DNA, nucleosome, chromatin, chromosome.
  • Adding nucleotides to the new strand is part of the elongation step of DNA synthesis.
  • RNA contains thymine.
  • Transcription occurs in the nucleus, and translation occurs in the cytoplasm.
  • Three "letters" of an RNA molecule code for a single amino acid.
  • DNA is not entirely or mostly made out of RNA.
  • The S phase is characterized by preparation for DNA synthesis.
  • A mutation in the gene for a cyclin protein might result in uncontrolled cell division.
  • Increasing specialization: pluripotency, multipotency, oligopotency, unipotency.
  • Hematopoietic stem cells give rise to red and white blood cells.

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Description

A fertilized egg develops into a complex organism through cell differentiation. Cells become specialized in structure and function to form tissues. The structures are optimally suited to perform specific functions to maintain homeostasis, a dynamic state of balance essential for life.

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