Cell Biology Quiz on Motor Proteins and Stem Cells
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Questions and Answers

What role do myosin motor proteins play in the cell?

  • They regulate microtubule stability.
  • They synthesize Okazaki fragments.
  • They degrade RNA and DNA.
  • They transport vesicles along actin filaments. (correct)

    • What is the primary function of Bcl-2 in a cell?

  • To facilitate RNA degradation.
  • To promote apoptosis.
  • To act as a DNA ligase.
  • To inhibit apoptosis. (correct)

    • How are Okazaki fragments removed during DNA replication?

  • By RNA polymerase.
  • By helicase.
  • By nucleases.
  • By DNA ligase. (correct)

    • Which statement about microtubules is true?

    <p>They play a role in cell division.</p> Signup and view all the answers

    What is the correct outcome for neurons competing for survival factors?

    <p>They may undergo apoptosis if they fail to compete.</p> Signup and view all the answers

    What is the function of calmodulin in cells?

    <p>To regulate intracellular Ca2+ concentration.</p> Signup and view all the answers

    What false statement is associated with nucleosome core particles?

    <p>They facilitate protein synthesis.</p> Signup and view all the answers

    What mechanism allows glycolipids to move between different membrane compartments?

    <p>Flippase floppase activity.</p> Signup and view all the answers

    What is a key advantage of using stem cells in drug testing and development?

    <p>They reduce the reliance on animal testing.</p> Signup and view all the answers

    Which type of stem cells is derived from embryos at the blastocyst stage?

    <p>Embryonic stem cells</p> Signup and view all the answers

    What is a significant concern associated with the use of embryonic stem cells?

    <p>They involve the destruction of embryos.</p> Signup and view all the answers

    Which of the following is a characteristic of adult stem cells?

    <p>They can differentiate into a limited range of cell types.</p> Signup and view all the answers

    Which of the following indicates a morphological change due to pro-apoptotic factors?

    <p>Cell shrinkage</p> Signup and view all the answers

    What is calmodulin primarily associated with in cellular processes?

    <p>Calcium ion binding</p> Signup and view all the answers

    What is essential for successful cell culturing?

    <p>Temperature and humidity control</p> Signup and view all the answers

    What represents the directed movement of cells towards a concentration gradient?

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

    Which of the following is a function of peroxisomes?

    <p>Detoxify hydrogen peroxide through catalase</p> Signup and view all the answers

    How did peroxisomes likely evolve according to the endosymbiotic theory?

    <p>Through the engulfment of free-living bacteria by a host cell</p> Signup and view all the answers

    Which of the following statements is true regarding G proteins?

    <p>GTP bound alpha subunits can activate downstream molecules</p> Signup and view all the answers

    What distinguishes symporters from antiporters?

    <p>Antiporters move substances in opposite directions</p> Signup and view all the answers

    Which type of transport mechanism allows solutes to cross a membrane more quickly?

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

    What happens in the rough endoplasmic reticulum (rER)?

    <p>Modification and folding of proteins</p> Signup and view all the answers

    What role does ATP play in the function of transporters?

    <p>It is only needed for active transport mechanisms</p> Signup and view all the answers

    What is one of the primary functions of the smooth endoplasmic reticulum (sER)?

    <p>Storage of calcium ions</p> Signup and view all the answers

    Which is NOT one of the criteria of terrestrial life?

    <p>Ability to fly</p> Signup and view all the answers

    Which statement is true regarding the RNA world theory?

    <p>RNA can catalyze its own replication</p> Signup and view all the answers

    What role does the nuclear lamina play in the nucleus?

    <p>It connects the inner and outer nuclear membranes</p> Signup and view all the answers

    Why is stem cell research considered crucial?

    <p>They offer potential in regenerative medicine</p> Signup and view all the answers

    What process is involved in the N-glycosylation of proteins?

    <p>Modification of oligosaccharide chains in the rER</p> Signup and view all the answers

    What is a significant role of the rough endoplasmic reticulum?

    <p>Synthesis of proteins for export</p> Signup and view all the answers

    Which characteristic is NOT associated with the functionality of the liver's rough endoplasmic reticulum?

    <p>Storage of calcium ions</p> Signup and view all the answers

    Which cellular movement is characterized by the cell moving in response to necrotic factors released by injured cells?

    <p>Necro taxis</p> Signup and view all the answers

    What is the primary effect of colchicine on microtubules?

    <p>Inhibits microtubule assembly</p> Signup and view all the answers

    Which statement correctly describes the role of GTP in microtubule dynamics?

    <p>GTP hydrolysis causes de-polymerization of tubulin.</p> Signup and view all the answers

    Which of the following accurately describes kinases in cellular processes?

    <p>They phosphorylate amino acids, impacting protein function.</p> Signup and view all the answers

    What is the relationship between microtubules and DNA replication?

    <p>Microtubules are important for cell division but not directly for DNA replication.</p> Signup and view all the answers

    What is the primary role of the cytoskeleton?

    <p>Provide structure and aid in movement</p> Signup and view all the answers

    Which characteristic is unique to mitochondria compared to other organelles?

    <p>Possession of own DNA</p> Signup and view all the answers

    What distinguishes intermediate filaments from other types of cytoskeletal structures?

    <p>Their diameter and mechanical strength</p> Signup and view all the answers

    Microtubules are primarily composed of which proteins?

    <p>Tubulin dimers</p> Signup and view all the answers

    What is a shared function of microfilaments, microtubules, and intermediate filaments in the cell?

    <p>Acting as dynamic structures for movement and stability</p> Signup and view all the answers

    Study Notes

    Cell Science Exam - Long Answer Tasks

    • Actin filaments: Provide tracks for vesicle transport by myosin motor proteins, facilitating intracellular transport and cellular organization.
    • Bcl-2 (B-cell-lymphoma 2): An anti-apoptotic protein, crucial in regulating apoptosis via the intrinsic mitochondrial pathway. Injecting Bcl-2 into a cell prevents apoptosis.
    • Okazaki fragments: Short, newly synthesized DNA fragments on the lagging strand during DNA replication. Ligases, not nucleases, remove RNA primers and join Okazaki fragments. Nucleases degrade RNA and DNA.
    • Microtubules: Involved in cell division and other cellular processes, not DNA replication. Polymerization, depolymerization, and motor proteins are important for these processes.
    • Developing neurons: Compete for survival factors, and those unsuccessful undergo programmed cell death (apoptosis), not necroptosis.
    • Calmodulin: A calcium-binding protein that regulates intracellular calcium levels.
    • Nucleosome core particles: Form 10nm fibers, not 30nm filaments. Wrapping DNA around the beads creates larger 30nm filaments.
    • Peroxisomes: Possess various functions: -Catalase: detoxifying H₂O₂. -Catabolism of very long chain fatty acids, amino acids, and branched fatty acids. -Reduction of reactive oxygen species.

    Origin of Peroxisomes

    • Endosymbiotic theory suggests they evolved from engulfed bacteria capable of performing oxidative reactions, establishing a symbiotic relationship.
    • Peroxisomes are part of the endomembrane system.

    GTP-bound and GDP-bound form of G proteins

    • GTP-bound alpha subunits directly interact with downstream molecules like adenylyl cyclase.
    • Nucleotide-free beta-gamma complex doesn't directly interact.
    • GDP-bound G proteins are inactive.

    Membrane Transport

    • Transporters: Generally operate slower than channels, often requiring ATP for active transport.
    • Channels: Allow for faster transport due to passive nature, facilitating direct passage through pores.
    • Symporters vs. Antiporters: Symporters move two substances in the same direction, while antiporters move them in opposite directions. Reversing the orientation can disrupt transport function.

    Endoplasmic Reticulum (ER)

    • Ribosomes in the rough ER synthesize proteins which are transported to the Golgi via vesicles.
    • Smooth ER is involved in lipid synthesis, calcium storage, steroid synthesis, detoxification, and glucose metabolism in the liver.

    Stem Cell Research

    • Regenerative medicine: Stem cells can differentiate into different cell types, potentially repairing damaged tissues and organs.
    • Disease modeling: Stem cells can model diseases, helping researchers understand disease mechanisms and develop drugs.
    • Drug development: Stem cells are a platform for testing drugs without using animals or humans.
    • Development and differentiation: Stem cells help understand the processes of development and differentiation in the human body.

    Cell Culturing Essential Factors

    • Physical parameters: temperature, oxygen/carbon dioxide levels, humidity, osmolarity, pH.
    • Aseptic conditions: Sterile environment, cell density, co-culture, feeder layer.
    • Chemical parameters: defined medium, serum, growth factors, hormones.

    Calmodulin

    • Calcium-binding protein that modifies target proteins based on Ca²⁺ concentration.

    Pro-apoptotic factors & their effects

    • Induce multiple morphological changes in cells including cell shrinkage, nuclear condensation & fragmentation, membrane blebbing, and loss of plasma membrane integrity.

    Cell Movement and signaling

    • Chemotaxis: Directed movement along a chemical gradient.
    • Chemokinesis: Random movement speed changes in response to a chemical gradient.
    • Haptotaxis: Directed movement along a surface gradient.
    • Mesenchymal Migration: Directed movement along a surface gradient.
    • Necrotaxis: Cell movement in response to necrotic factors.
    • Kinases: Phosphorylate amino acids, causing conformational changes in target proteins, altering their activities, localization, and interactions. ATP hydrolysis, not GTP, is important in cellular processes like cell cycle regulation and signal transduction.

    Microtubules, Microfilaments, and Intermediate Filaments

    • Diverse functions: Movement, structure, and cell stability.
    • Dynamic structures: Assembly/disassembly.

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    Description

    This quiz covers essential topics in cell biology, including the roles of myosin motor proteins, Bcl-2, and the significance of various stem cells. Test your knowledge on cellular mechanisms, molecular functions, and the implications of stem cell research in drug development. Perfect for students reviewing key concepts in cell biology.

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