unit 1 bio exam reicse
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What is the process in which the plasma membrane folds around and engulfs materials by an infolding of the plasma membrane?

Endocytosis

What is the term for a secretory vesicle fusing with the plasma membrane to expel waste from the cell?

Exocytosis

What type of molecules are hydrophilic and attracted to water?

  • Hydrophobic
  • Polar
  • Nonpolar
  • Hydrophilic (correct)

    • Passive transport moves along the concentration gradient, while active transport moves ________ the concentration gradient.

    <p>against</p> Signup and view all the answers

    Match the following components of the cell membrane with their descriptions:

    <p>Phospholipid bilayer = Created by two layers of phospholipids Cholesterol = Acts as spacers to keep phospholipids from becoming too closely packed Integral proteins = Span the entire width of the plasma membrane Peripheral proteins = Found on the exterior side of the plasma membrane</p> Signup and view all the answers

    What is the function of the Rough Endoplasmic Reticulum (ER)?

    <p>Helps to make and send proteins off for the cell to use.</p> Signup and view all the answers

    What is the function of the Smooth Endoplasmic Reticulum (ER)?

    <p>Production of steroids and hormones, as well as the synthesis of important lipids like phospholipids and cholesterol.</p> Signup and view all the answers

    What is the primary function of Lysosomes?

    <p>Degrades waste material within and from the outside of the cell.</p> Signup and view all the answers

    Describe the function of the Nucleus.

    <p>Houses the DNA in the cell and helps to control the cell processes.</p> Signup and view all the answers

    Match the following cell components with their functions:

    <p>Nucleolus = Produces ribosomes Nuclear Envelope = Separates the nucleus from the cytoplasm Lysosomes = Degrades waste material within the cell Smooth ER = Production of lipids and hormones Golgi Apparatus = Processes and transports proteins Rough ER = Involved in protein synthesis and transportation Ribosomes = Site of protein synthesis</p> Signup and view all the answers

    What distinguishes osmosis from diffusion?

    <p>Osmosis can only occur through a semipermeable membrane</p> Signup and view all the answers

    Contrast facilitated diffusion with simple diffusion.

    <p>Facilitated diffusion is helped/facilitated by transport proteins like carriers and channel proteins. In contrast, simple diffusion can occur without the help of proteins.</p> Signup and view all the answers

    Why does active transport require energy whereas facilitated diffusion does not?

    <p>Active transport requires energy because the molecules are transported against their concentration gradient, from low to high concentration. Facilitated diffusion relies on passive transport mechanisms and does not move molecules against a concentration gradient.</p> Signup and view all the answers

    Why are endocytosis and exocytosis called bulk transport?

    <p>They involve large amounts of substance transport</p> Signup and view all the answers

    Why is it necessary for eukaryotic cells to have organelles whereas prokaryotes do not?

    <p>Eukaryotic cells are larger and more complex, requiring organelles to compartmentalize different metabolic processes and maintain efficiency. Prokaryotic cells, being simpler, do not need membrane-bound organelles.</p> Signup and view all the answers

    What are the internal factors that can affect the cell cycle?

    <p>Cyclins and Kinases</p> Signup and view all the answers

    What is the basic definition of apoptosis?

    <p>Programmed cell death</p> Signup and view all the answers

    Necrosis is the programmed death of a cell.

    <p>False</p> Signup and view all the answers

    Cancer cells form due to a mutation in the DNA of a cell that has the ability to block ______ signal pathways.

    <p>death</p> Signup and view all the answers

    What is mechanical digestion?

    <p>Physical break down of food through processes like chopping, smashing, chewing, and peristalsis.</p> Signup and view all the answers

    What is peristalsis and where does it occur?

    <p>Peristalsis is an involuntary process that pushes food down the esophagus through muscular contractions. It occurs in the esophagus.</p> Signup and view all the answers

    What is bile's role in digestion?

    <p>Bile aids in the emulsification of fats, breaking them down into smaller molecules that can be easily digested.</p> Signup and view all the answers

    What substance is produced by the stomach for digestion?

    <p>The stomach produces protein-digesting enzymes (proteases like Pepsin and Rennin) and gastric juice.</p> Signup and view all the answers

    What role does the duodenum play in digestion?

    <p>The duodenum produces hormones like secretin, which stimulate the pancreas to release bicarbonate to neutralize stomach acid.</p> Signup and view all the answers

    What is the process by which cells are programmed to die?

    <p>Apoptosis</p> Signup and view all the answers

    What is cancer?

    <p>A disease that occurs when cells in the body grow and divide uncontrollably, leading to the development of abnormal tissue masses known as tumors.</p> Signup and view all the answers

    What is the advantage of multicellular organisms in terms of resisting programmed cell death?

    <p>Resistance to programmed cell death (apoptosis)</p> Signup and view all the answers

    How do cells become cancerous?

    <p>When the DNA of a cell becomes mutated, usually due to incorrect cell duplication or exposure to mutagens like tobacco.</p> Signup and view all the answers

    Define stem cells.

    <p>Undifferentiated cells with the ability to develop into different types of specialized cells in the body.</p> Signup and view all the answers

    Define differentiation.

    <p>The process driven by changes in gene expression that lead to the development of specialized cell types.</p> Signup and view all the answers

    What do tumor suppressor genes code for?

    <p>Proteins that help slow down cell division and allow apoptosis to occur</p> Signup and view all the answers

    Which checkpoint stops the cell cycle if some of the spindle fibers have not attached to the sister chromatids?

    <p>M checkpoint</p> Signup and view all the answers

    Name 3 phases of the cell cycle associated with the three checkpoints.

    <p>Metaphase (Mitosis), G1 phase (interphase), and G2 phase (interphase)</p> Signup and view all the answers

    What happens if the DNA has not been correctly copied in a cell?

    <p>The cell will attempt to fix the DNA replication at first. If unsuccessful, apoptosis (programmed cell death) occurs.</p> Signup and view all the answers

    How is the p53 gene involved in repairing DNA and apoptosis?

    <p>The p53 gene, a tumor suppressor gene, attempts to repair DNA damage or problematic issues within the cell before triggering apoptosis.</p> Signup and view all the answers

    What is the meaning of 'Uni' in the context of unicellular organisms?

    <p>only one</p> Signup and view all the answers

    What is the most likely outcome of a DNA mutation in the p53 gene?

    <p>Growth and spread of cancer cells; uncontrollable cell division</p> Signup and view all the answers

    What are the advantages of unicellular organisms? (Select all that apply)

    <p>Able to rapidly reproduce</p> Signup and view all the answers

    Explain why unicellular organisms have a shorter life span compared to multicellular organisms.

    <p>1 cell wears itself out</p> Signup and view all the answers

    Define differentiation in terms of cell biology.

    <p>When cells take on specific roles in the body and become specialized; irreversible process</p> Signup and view all the answers

    What is the potency of a cell?

    <p>The ability of a cell to differentiate into different cell types, ranging from low to high potency</p> Signup and view all the answers

    Unicellular organisms are at more risk of _________ changes.

    <p>environmental</p> Signup and view all the answers

    Explain the concept of totipotent cells.

    <p>Totipotent cells can differentiate into any cell type in the body and are found in the early embryo.</p> Signup and view all the answers

    Specialized cells perform a general role in an organism.

    <p>False</p> Signup and view all the answers

    Describe pluripotent cells.

    <p>Pluripotent cells can differentiate into many cell types but not all types, found in embryonic stem cells.</p> Signup and view all the answers

    Match the term with its definition:

    <p>Organ = A part of an organism that is typically self-contained System = A set of organs and tissues working together Tissue = A group or layer of cells that work together Specialized cell = A cell designed to carry out a particular role</p> Signup and view all the answers

    Explain the characteristics of multipotent cells.

    <p>Multipotent cells can differentiate into a limited range of cell types related to a specific lineage or tissue.</p> Signup and view all the answers

    Define the digestive system.

    <p>in charge of the breaking down of foods</p> Signup and view all the answers

    Which major biomacromolecule is needed for the body to function properly?

    <p>Proteins</p> Signup and view all the answers

    Study Notes

    Cell Theory

    • Cells are the smallest basic unit of life.
    • All living things are made up of cells.
    • All cells are made from pre-existing cells.

    Organelles and Functions

    • Nucleus: Houses the DNA in the cell, helps to control the cell processes. Control centre of the cell.
    • Rough ER: Helps to make and send proteins off for the cell to use.
    • Smooth ER: Production of steroids and hormones, as well as the synthesis of important lipids, like phospholipids and cholesterol.
    • Lysosomes: Degrades waste material from within and outside the cell.
    • Cytoskeleton: Keeps the cell's shape and helps maintain a strong structure for the cell.
    • Mitochondria: Creates energy for the cell to use in all necessary processes. Site of cellular respiration.
    • Chloroplast: Where photosynthesis takes place (found in plant cells). Site of photosynthesis.
    • Ribosomes: Site of protein synthesis.
    • Golgi Apparatus: Processes and transports proteins that can be used in other areas both outside and inside the cell.
    • Cytoplasm: Jelly-like fluid found within the cell, where most chemical reactions take place.

    Cell Membrane and Wall

    • Cell Membrane: Helps with chemical signalling, recognises other cells, and keeps the inside environment of the cell stable.
    • Cell Wall: Protects the cell from mechanical or osmotic stress, found on the outside of the cell.

    Transport and Movement

    • Endocytosis: Plasma membrane folds around and engulfs materials by an infolding of the plasma membrane.
    • Exocytosis: A secretory vesicle fuses with the plasma membrane and expels waste from the cell into the extracellular space.
    • Passive Transport: Moves along the concentration gradient, including osmosis and simple diffusion.

    Cell Size and SA: V Ratio

    • Cell size is limited due to the inability of very large cells to provide nutrients and water and remove wastes efficiently.
    • Smaller cells have a larger SA: V ratio, allowing for faster diffusion and maintenance of internal environment.

    Fluid Mosaic Model

    • Phospholipid Bilayer: Created by two layers of phospholipids, which automatically rearrange themselves to avoid the fluids in the extra/intracellular space.
    • Fatty Acid Tails: Hydrophobic tails turn away from the water on the outside and inside the cell.
    • Phosphate Heads: Hydrophilic heads turn towards the water on the outside and inside the cell.
    • Cholesterol: In between phospholipid tails, helps maintain fluidity and prevents freezing or overheating.

    Prokaryotic vs Eukaryotic Cells

    • Prokaryotic Cells: Lack membrane-bound organelles, have no nucleus (DNA is stored in the nucleoid), and are typically smaller.

    • Eukaryotic Cells: Have membrane-bound organelles (such as the nucleus, mitochondria, chloroplast, Golgi apparatus, and Endoplasmic reticulum), and are typically larger.### Cell Biology

    • All living organisms are made up of cells, which are the smallest organizational unit of life.

    • Cells come from pre-existing cells.

    Cell Size and Surface to Volume Ratio

    • Cells are microscopic because their surface area to volume (SA:V) ratio is larger, allowing for faster diffusion.
    • Diffusion is important for cells to maintain proper exchange of nutrients and waste.

    Passive Transport

    • Diffusion: the movement of molecules from a high concentration to a low concentration without the use of proteins or energy.
    • Examples of molecules that use diffusion:
      • Oxygen and Carbon Dioxide molecules
    • Osmosis: the movement of water molecules through a semipermeable membrane from a high concentration to a low concentration.
    • Facilitated diffusion: the movement of molecules through a plasma membrane with the help of transport proteins (carrier and channel proteins).
    • Examples of molecules that use facilitated diffusion:
      • Amino acids, ions (small polar molecules)

    Active Transport

    • The movement of molecules through a plasma membrane that uses energy to move against the concentration gradient.
    • Examples of molecules that use active transport:
      • Ions, glucose, and amino acids
    • Active transport requires energy because it transports molecules against their concentration gradient.

    Cell Theory

    • All cells are made up of cells
    • Cells are the smallest organizational unit of life
    • All cells come from pre-existing cells

    Cell Cycle

    • The cell cycle is the process of cell growth, replication, and division.
    • The cell cycle consists of three main stages: interphase, mitosis, and cytokinesis.
    • Interphase: the stage of cell growth and preparation for replication.
      • G1 (Gap 1): initial growth phase, where the cell grows to its full size.
      • S (Synthesis): the stage of DNA synthesis, where the DNA is replicated.
      • G2 (Gap 2): the stage of final preparation for cell division, where organelles are replicated.
    • Mitosis: the stage of nucleus replication, consisting of four main phases:
      • Prophase: the stage of chromosome condensation and spindle fibre formation.
      • Metaphase: the stage of chromosome alignment at the equator.
      • Anaphase: the stage of chromosome separation.
      • Telophase: the stage of nuclear envelope reformation.
    • Cytokinesis: the stage of cytoplasmic division and cell separation.

    Cell Division

    • Cell division is the process of cell replication and division.
    • Reasons for cell division:
      • Cell growth and development
      • Tissue repair
      • Replacement of damaged cells
    • Cell division can be affected by:
      • External factors: chemical and physical signals, cell-to-cell contact, and growth factors.
      • Internal factors: cyclins, kinases, and tumour suppressor genes.

    Apoptosis

    • Apoptosis is the process of programmed cell death.
    • Reasons for apoptosis:
      • DNA damage or mutation
      • Infection with a virus
      • Overproduction of cells
      • Wrong or incomplete cell division
    • Apoptosis is a controlled process that eliminates unwanted or abnormal cells during embryonic development and tissue homeostasis.

    Cancer Cells

    • Cancer cells form due to a mutation in the DNA that blocks death signal pathways.

    • Cancer cells uncontrollably divide and can stop other cells from working properly.

    • p53 is a tumour suppressor gene that helps to regulate cell division and apoptosis.

    • Mutation can be caused by physical, chemical, biological, or environmental factors.### Apoptosis and Cell Cycle Regulation

    • Apoptosis is a process of programmed cell death, and it's regulated by pro-apoptotic and anti-apoptotic genes.

    • BCL-2 family genes (BCL-2, BCL-XL, MCL-1, BFL-1, BCL-W, BCL2L10) possess BH1-4 domains and maintain the outer mitochondrial membrane integrity.

    • These genes are involved in controlling the cell cycle and inhibit the pro-apoptotic members.

    Proto-Oncogenes and Oncogenes

    • Proto-oncogenes are genes that stimulate cell division and promote survival and proliferation in normal cells.
    • They code for proteins that act as growth factors, signaling molecules, or transcription factors.
    • Mutated proto-oncogenes become oncogenes, which accelerate cell division and promote the growth of cancer cells.
    • Oncogenes can cause cancer by stimulating cell division and accelerating cell growth.

    Tumor Suppressor Genes

    • Tumor suppressor genes (pro-apoptotic genes) code for proteins that inhibit cell division, detect and repair DNA mistakes, and stimulate apoptosis if the cell is irreparable.
    • These genes act as brakes to slow down or stop cell division.
    • Mutations in tumor suppressor genes can cause cancer by stopping them from inhibiting cell division.

    Cell Cycle Regulation

    • The cell cycle control system ensures that no abnormalities occur during the cell cycle.
    • Checkpoints (M, G1, G2) ensure that the cell cycle pauses if there are any abnormalities.
    • The p53 gene is a tumor suppressor gene that attempts to repair DNA damage or induce apoptosis if the damage is irreparable.

    Stem Cells

    • Stem cells are unspecialized cells that have no specific role or job within the body.
    • Types of stem cells:
      • Totipotent: can differentiate into any cell in the body (e.g., Morula cells, 3 days after fertilization).
      • Pluripotent: can differentiate into many different types of cells, but not any type of cell (e.g., Embryonic stem cells, inner cell mass of blastocysts).
      • Multipotent: can differentiate into a limited number of cell types (e.g., Adult stem cells, Ectoderm, Mesoderm, Endoderm).
      • Oligopotent: can differentiate into a few cell types (e.g., Adult lymphoid or myeloid).
      • Unipotent: can differentiate into a specific type of cell (e.g., muscle stem cells).

    Apoptosis Pathways

    • Intrinsic pathway: DNA damage activates the intrinsic pathway, which involves the activation of ATM protein, p53, and BCL-2 family proteins.
    • Extrinsic pathway: involves the activation of natural killer cells or cytotoxic T cells, which release Perforin and Granzyme, leading to the activation of Casp-8 and Casp-3.

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