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Questions and Answers
What is the primary function of the plasma membrane?
What is the primary function of the plasma membrane?
Eukaryotic cells are the only type of cells that possess membranous organelles.
Eukaryotic cells are the only type of cells that possess membranous organelles.
True
How many different types of cells exist in the human body?
How many different types of cells exist in the human body?
approximately 200
The __________ is a jelly-like fluid that fills the space between organelles in a cell.
The __________ is a jelly-like fluid that fills the space between organelles in a cell.
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Match the organelle type with its primary function:
Match the organelle type with its primary function:
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Which of the following structures is made primarily of actin and myosin?
Which of the following structures is made primarily of actin and myosin?
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Microtubules are static and do not change in composition during cellular processes.
Microtubules are static and do not change in composition during cellular processes.
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What is the role of the cytoskeleton in a cell?
What is the role of the cytoskeleton in a cell?
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What is the role of the sodium-potassium (Na+-K+) pump in animal cells?
What is the role of the sodium-potassium (Na+-K+) pump in animal cells?
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Secondary active transporters move solutes against their concentration gradient without the use of ATP.
Secondary active transporters move solutes against their concentration gradient without the use of ATP.
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What is the mechanism called when a cell engulfs a large particle and internalizes it into a vesicle?
What is the mechanism called when a cell engulfs a large particle and internalizes it into a vesicle?
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Water moves through aquaporins across the plasma membrane, facilitating diffusion_.
Water moves through aquaporins across the plasma membrane, facilitating diffusion_.
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Match the types of solutions with their effects on a red blood cell:
Match the types of solutions with their effects on a red blood cell:
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What is the primary function of cilia in cells?
What is the primary function of cilia in cells?
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The centrosome contains long microtubules called centrioles.
The centrosome contains long microtubules called centrioles.
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What are the small holes in the nuclear envelope that allow for the exit of mRNAs?
What are the small holes in the nuclear envelope that allow for the exit of mRNAs?
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Ribosomes are assembled in the ____________.
Ribosomes are assembled in the ____________.
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What is the main function of the smooth endoplasmic reticulum?
What is the main function of the smooth endoplasmic reticulum?
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The Golgi complex is responsible for breaking down cellular molecules.
The Golgi complex is responsible for breaking down cellular molecules.
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The ____________ is all of the DNA in an organism.
The ____________ is all of the DNA in an organism.
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Match the organelle with its primary function:
Match the organelle with its primary function:
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What type of RNA is bound by ribosomal subunits during translation?
What type of RNA is bound by ribosomal subunits during translation?
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What disease results from defective lysosomes?
What disease results from defective lysosomes?
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What is the primary function of mitochondria in cells?
What is the primary function of mitochondria in cells?
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Mitochondria contain their own DNA and replicate independently of the nuclear genome.
Mitochondria contain their own DNA and replicate independently of the nuclear genome.
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Identify the structure formed by the extensive folding of the inner mitochondrial membrane.
Identify the structure formed by the extensive folding of the inner mitochondrial membrane.
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Aerobic cellular respiration ends with the synthesis of __________.
Aerobic cellular respiration ends with the synthesis of __________.
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Match the phases of mitosis with their descriptions:
Match the phases of mitosis with their descriptions:
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What term describes the division of the cytoplasmic components after mitosis?
What term describes the division of the cytoplasmic components after mitosis?
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Telomeres protect chromosomes from shortening by capping their ends.
Telomeres protect chromosomes from shortening by capping their ends.
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What is the result of meiosis II?
What is the result of meiosis II?
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The sequence of events during somatic cell division is called the __________.
The sequence of events during somatic cell division is called the __________.
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Which statement is true regarding human chromosomes?
Which statement is true regarding human chromosomes?
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What percentage of the membrane is composed of phospholipids?
What percentage of the membrane is composed of phospholipids?
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Cholesterol decreases membrane fluidity.
Cholesterol decreases membrane fluidity.
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Define membrane fluidity.
Define membrane fluidity.
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The membrane is permeable to _______ molecules like O2 and CO2, as they can travel through the membrane without help.
The membrane is permeable to _______ molecules like O2 and CO2, as they can travel through the membrane without help.
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Match the following types of membrane proteins with their functions:
Match the following types of membrane proteins with their functions:
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Which statement about membrane fluidity is correct?
Which statement about membrane fluidity is correct?
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Active transport does not require metabolic energy.
Active transport does not require metabolic energy.
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What role do ion channels play in facilitated diffusion?
What role do ion channels play in facilitated diffusion?
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A _______ gradient refers to the difference in concentration of a substance within a system.
A _______ gradient refers to the difference in concentration of a substance within a system.
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What happens to the rate of diffusion as temperature increases?
What happens to the rate of diffusion as temperature increases?
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Study Notes
Introduction to Cells
- Cells vary greatly in shape and size, with approximately 200 distinct types present in the human body.
- Cells serve as the fundamental unit of life, organized into specialized subunits called organelles, which perform specific functions.
- Only eukaryotic cells, such as human cells, contain membranous organelles.
Organelles of Eukaryotic Cells
- The plasma membrane functions as a flexible barrier, regulating material exchange and facilitating cell communication.
- Cytoplasm includes all components between the plasma membrane and nucleus, providing an environment for chemical reactions.
- The cytoskeleton, made from actin, myosin, intermediate filaments, and microtubules, provides structure, stability, and movement to cells.
- Organizes microtubules within centrosomes, which play a crucial role during cell division through the formation of the mitotic spindle.
- Structures like cilia and flagella assist in cellular movement: cilia are short and move fluid, while flagella are long and propel cells.
Nucleus and DNA
- The nucleus, a membranous organelle, houses DNA within a double membrane called the nuclear envelope, punctuated by nuclear pores.
- DNA must be compacted to fit within the cell; it can exist as chromatin (loose form) or tightly packed chromosomes (condensed).
- Ribosomes, composed of rRNA and protein, synthesize proteins from mRNA in a process known as translation, occurring in the cytoplasm.
Endoplasmic Reticulum and Golgi Complex
- The rough endoplasmic reticulum (rER) contains ribosomes, synthesizing proteins for organelles while being continuous with the nuclear membrane.
- The smooth endoplasmic reticulum (sER) synthesizes lipids, metabolizes carbohydrates, and stores calcium ions.
- The Golgi complex modifies, sorts, and packages proteins into vesicles. It has distinct entry and exit faces for efficient processing.
Lysosomes, Peroxisomes, and Proteasomes
- Lysosomes contain enzymes for breaking down cellular materials and recycling waste. Dysfunction can lead to diseases like Tay-Sachs.
- Peroxisomes oxidize molecules, metabolizing fatty acids and detoxifying substances like alcohol.
- Proteasomes degrade proteins into smaller peptides, playing a role in cell regulation; dysfunction can be linked to neurodegenerative diseases.
Mitochondria
- Mitochondria are known as the powerhouses of the cell, involved in aerobic cellular respiration and ATP production.
- They feature two membranes, with the inner membrane extensively folded to increase surface area for energy reactions.
- Unique in having their own DNA, mitochondria are maternally inherited and play a role in apoptotic pathways.
Cell Division
- Somatic cells undergo mitosis and cytokinesis, involving a series of phases known as the cell cycle: G1, S, and G2 phases prepare for division.
- Mitosis consists of four stages: prophase, metaphase, anaphase, and telophase, ultimately followed by cytokinesis.
- Telomeres protect chromosome ends and shorten with age, influencing aging processes and cancer development due to their effect on cell division.
Reproductive Cell Division
- Meiosis produces haploid gametes through two divisions, including genetic crossover to promote diversity.
- Meiosis I separates homologous chromosomes, while meiosis II separates sister chromatids, resulting in four non-identical daughter cells.
Membrane Structure and Function
- The plasma membrane's fluid mosaic model describes its flexible permeability, allowing selective transport of substances.
- The lipid bilayer comprises phospholipids, making up 75% of the membrane, with cholesterol and glycolipids comprising 20% and 5%, respectively.
- Membrane fluidity is influenced by fatty acid saturation and temperature; unsaturated fatty acids enhance fluidity compared to saturated ones.
Transport Mechanisms
- Nonpolar molecules diffuse freely across membranes, while polar substances require assistance via facilitated diffusion through protein channels.
- Active transport mechanisms move substances against their gradients, necessitating energy but enabling maintenance of specific ion concentrations within cells.### Active Transport Mechanisms
- Active transport involves moving solutes against concentration gradients across membranes.
- Sodium-potassium (Na+-K+) pump in animal cells maintains higher Na+ concentration outside the cell and higher K+ concentration inside.
- The Na+-K+ pump is a primary active transporter that utilizes ATP hydrolysis to function.
Types of Active Transporters
- Primary active transporters require ATP directly to move solutes against their gradients.
- Secondary active transporters do not use ATP directly; instead, they rely on electrochemical gradients created by primary transporters.
- Secondary active transporters transport two solutes; one moves down its gradient, releasing free energy, while the other moves against its gradient.
Types of Secondary Active Transport
- Symporters allow both solutes to flow in the same direction.
- Antiporters transport solutes in opposite directions.
Effects of Cyanide on Active Transport
- Cyanide inhibits ATP production, resulting in loss of all forms of active transport due to lack of energy.
Vesicular Transport
- Vesicles are membrane sacs used for transporting substances between organelles.
- Endocytosis is the process of moving substances into cells; exocytosis refers to the release of substances out of cells, also known as secretion.
- Both processes require ATP hydrolysis.
- Transcytosis involves substances moving through cells by sequential endocytosis and exocytosis.
Endocytosis Types
- Receptor-mediated endocytosis specifically imports selected molecules into cells.
- Phagocytosis is a process where phagocytic cells "eat" cells or molecules, engulfing them into a vesicle for digestion by lysosomes.
- Pinocytosis, or "cell drinking," involves the uptake of dissolved solutes into large vesicles.
Osmosis and Water Movement
- Osmosis is the movement of water from low solute concentration to high concentration across a semi-permeable membrane.
- Aquaporins are specialized channel proteins that facilitate efficient water movement across cell membranes.
Cell Responses to Solutions
- Hypertonic solutions have higher solute concentrations than the inside of the cell, causing water to flow out and resulting in cell shrinkage.
- Hypotonic solutions have lower solute concentrations, resulting in water flowing into the cell and potentially causing it to swell.
- Isotonic solutions have equal solute concentration inside and outside the cell, resulting in no net water movement.
Osmolarity and Tonicity
- Osmolarity defines the total solute concentration of a solution, impacting how cells behave when exposed to different solutions.
- The osmolarity of solutions is crucial for determining their tonicity: isotonic, hypotonic, or hypertonic.
- Understanding osmolarity is essential, especially in medical contexts like intravenous (IV) fluids, which should be isotonic to maintain cell integrity.
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Description
Explore the fascinating world of eukaryotic cells and their organelles. Understand the roles of the plasma membrane, cytoplasm, and cytoskeleton in cell function. This quiz will test your knowledge of the various types of cells and their specialized structures.
