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

What is the function of calmodulin in cells?

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

What false statement is associated with nucleosome core particles?

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

What mechanism allows glycolipids to move between different membrane compartments?

<p>Flippase floppase activity. (D)</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. (A)</p> Signup and view all the answers

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

<p>Embryonic stem cells (A)</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. (A)</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. (A)</p> Signup and view all the answers

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

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

What is calmodulin primarily associated with in cellular processes?

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

What is essential for successful cell culturing?

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

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

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

Which of the following is a function of peroxisomes?

<p>Detoxify hydrogen peroxide through catalase (D)</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 (C)</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 (B)</p> Signup and view all the answers

What distinguishes symporters from antiporters?

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

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

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

What happens in the rough endoplasmic reticulum (rER)?

<p>Modification and folding of proteins (A)</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 (C)</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 (B)</p> Signup and view all the answers

Which is NOT one of the criteria of terrestrial life?

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

Which statement is true regarding the RNA world theory?

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

Why is stem cell research considered crucial?

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

What is a significant role of the rough endoplasmic reticulum?

<p>Synthesis of proteins for export (B)</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 (D)</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 (C)</p> Signup and view all the answers

What is the primary effect of colchicine on microtubules?

<p>Inhibits microtubule assembly (C)</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. (A)</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. (A)</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. (C)</p> Signup and view all the answers

What is the primary role of the cytoskeleton?

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

Which characteristic is unique to mitochondria compared to other organelles?

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

What distinguishes intermediate filaments from other types of cytoskeletal structures?

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

Microtubules are primarily composed of which proteins?

<p>Tubulin dimers (B)</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 (C)</p> Signup and view all the answers

Flashcards

Myosin and Actin in Vesicle Transport

Myosin motor proteins move vesicles along actin filaments, enabling intracellular transport and cellular organization.

Bcl-2 and Apoptosis

Bcl-2 is an anti-apoptotic protein that blocks the cell's programmed death pathway.

Okazaki Fragments and DNA Ligase

Okazaki fragments are short DNA segments synthesized on the lagging strand during replication. DNA ligase joins these fragments, not nucleases.

Microtubules and DNA Replication

Microtubules play critical roles in cell division and other processes, not in DNA replication.

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Neuronal Survival and Apoptosis

Developing neurons compete for limited survival factors. Lack of these factors can lead to programmed cell death (apoptosis), not necrosis.

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Calmodulin and Calcium Regulation

Calmodulin is a protein that binds calcium ions, regulating their concentration within the cell.

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Nucleosome Core Size and Structure

Nucleosome cores are about 10nm in diameter. They wrap around DNA to form a more compact 30nm filament.

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Glycolipid Movement in Membranes

Flippase and floppase enzymes move glycolipids between the layers of a lipid bilayer.

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What are peroxisomes?

Peroxisomes are organelles that play a vital role in various metabolic processes within the cell.

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What does catalase do?

Catalase is an enzyme found in peroxisomes that breaks down hydrogen peroxide (H2O2), a toxic byproduct of cellular metabolism, into water and oxygen.

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What are very-long-chain fatty acids (VLCFA) broken down in?

Breakdown of very-long-chain fatty acids (VLCFA) is a major function of peroxisomes.

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What does the breakdown of amino acids involve?

Peroxisomes play a role in the breakdown of amino acids, which are the building blocks of proteins.

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What does the breakdown of branched fatty acids involve?

Peroxisomes can break down branched-chain fatty acids, a specific type of fatty acid with a unique structure.

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What are reactive oxygen species (ROS)?

Peroxisomes can reduce other reactive oxygen species (ROS), molecules that can cause cellular damage.

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How did peroxisomes evolve?

The endosymbiotic theory suggests that peroxisomes evolved through the engulfment of a free-living bacterium by a eukaryotic cell. This engulfed bacterium was capable of performing oxidative reactions, which led to a symbiotic relationship and the specialization of the peroxisome into a distinct organelle with various metabolic functions.

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How do G proteins activate other molecules?

Both the GTP-bound alpha subunit and the nucleotide-free beta-gamma complex can activate other molecules downstream of GPCRs. However, the GDP-bound G protein is inactive and does not activate other molecules.

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Chemokinesis

Movement towards a higher concentration gradient of a chemical signal in the fluid.

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Mesenchymal migration

Movement along a surface due to a gradient of a surface-bound molecule.

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Kinases

Enzymes that add a phosphate group to a protein, often altering its activity.

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Dynein

A type of motor protein that uses ATP to bend flagella and cilia.

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GTP hydrolysis in microtubules

Hydrolysis of GTP promotes depolymerization of tubulin, causing the microtubule to break down.

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What is rough ER and its function?

The endoplasmic reticulum (ER) is a network of membranes that plays a crucial role in protein synthesis and modification. Rough ER (rER) is studded with ribosomes, which are responsible for protein synthesis. The rER is involved in folding newly synthesized polypeptides into their correct 3D structures, glycosylation, and quality control.

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What is smooth ER and its function?

The smooth endoplasmic reticulum (sER) is a network of membranes that does not have ribosomes attached. It is involved in the synthesis of lipids, storage of calcium ions, steroid synthesis, detoxification, and glucose metabolism.

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What is the RNA world theory?

The RNA world theory proposes that RNA, not DNA, was the primary genetic material in early life. It suggests that RNA could self-replicate and catalyze enzymatic reactions. RNA's simpler structure and ability to form spontaneously make it a likely candidate for an early life form.

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What is the nuclear lamina?

The nuclear lamina is a network of protein filaments that lines the inner surface of the nuclear envelope. It provides structural support for the nucleus and plays a role in regulating nuclear processes such as DNA replication and transcription.

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Why is stem cell research important?

Stem cell research is crucial because of its potential for regenerative medicine, disease modeling, and drug development. Stem cells have the ability to differentiate into various cell types, making them valuable for repairing damaged tissues and organs. They also allow researchers to create models of disease in the lab for studying disease mechanisms and developing new therapies.

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What are stem cells?

Specialized cells that can differentiate into other cell types and renew themselves, playing a key role in development and tissue repair.

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What are embryonic stem cells?

Derived from embryos at the blastocyst stage, these pluripotent cells can become any cell type in the body.

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What are adult stem cells?

Found in various tissues, these cells are multipotent and can only differentiate into a limited range of cell types within a specific tissue or organ.

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What is induced pluripotent stem cell (iPSC) technology?

The process of creating stem cells from adult cells by reprogramming them to have properties similar to those of embryonic stem cells.

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What are the key parameters for cell culture?

Factors essential for maintaining cell cultures, including temperature, oxygen/carbon dioxide levels, humidity, solution density, acidity, and sterile conditions.

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What is calmodulin?

A calcium-binding protein that regulates the activity of various target proteins based on calcium concentrations.

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What is chemotaxis?

The directed movement of cells towards a higher concentration of a specific molecule.

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Describe the morphological changes observed during apoptosis.

A series of changes that occur in a cell undergoing programmed cell death, including cell shrinkage, nuclear condensation and fragmentation, membrane blebbing, loss of membrane integrity, and fragmentation into apoptotic bodies.

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What is a mitochondrion?

Mitochondria are powerhouses of the cell, producing ATP. They have their own DNA and ribosomes, suggesting a prokaryotic origin.

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What is the cytoskeleton?

The cytoskeleton provides structural support, allowing for cell movement and transport of materials within the cell. It's a dynamic network that changes with cell activity.

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What are microtubules?

Microtubules are large protein tubes found in the cytoskeleton. Made of tubulin dimers, they help organize organelles and transport materials inside the cell.

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What are intermediate filaments?

Intermediate filaments are rope-like fibers providing structural support and strength. They connect cells and form a network that helps maintain tissue integrity.

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What are microfilaments?

Microfilaments are thin, actin-based threads that help control a cell's shape and allow for movement. They're important for muscle contraction.

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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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