Cell Cycle Control & Mitosis Quiz
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Questions and Answers

What is the term for the body cells produced by mitosis that contain the diploid number of chromosomes?

  • Sperm cells
  • Somatic cells (correct)
  • Germ cells
  • Ovum cells

    • During which phase of the cell cycle do chromatin fibers condense to form chromosomes?

  • Prophase (correct)
  • Anaphase
  • Interphase
  • Cytokinesis

    • How many chromosomes do human germ cells contain?

  • 22 chromosomes
  • 23 chromosomes (correct)
  • 46 chromosomes
  • 44 chromosomes

    • In female somatic cells, which chromosomes are active for transcription?

    <p>Only one of the X chromosomes</p> Signup and view all the answers

    What process occurs at the conclusion of the G2 phase to complete the cell cycle?

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

    What divides first during the process of mitosis?

    <p>Nuclear material</p> Signup and view all the answers

    Which phase involves the disappearance of the nucleolus?

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

    How many pairs of chromosomes do somatic cells have?

    <p>22 pairs</p> Signup and view all the answers

    What is formed from the division of the cytoplasm in mitosis?

    <p>Daughter cells</p> Signup and view all the answers

    Which method involves the degradation of phagocytosed material primarily by lysosomal enzymes?

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

    What is the role of autophagy in cellular function?

    <p>Eliminates damaged organelles and proteins</p> Signup and view all the answers

    What are autophagosomes primarily composed of during their formation?

    <p>Double-membrane vesicles surrounding cytoplasm and organelles</p> Signup and view all the answers

    Which environmental conditions are known to induce autophagy?

    <p>Food deprivation and hypoxia</p> Signup and view all the answers

    What is a residual body in the context of lysosomal function?

    <p>Material that remains undigested after lysosomal processing</p> Signup and view all the answers

    What is the primary role of the molecular machinery found in the nucleus?

    <p>To synthesize and process RNA types</p> Signup and view all the answers

    What mainly constitutes the nuclear envelope?

    <p>A double membrane with perinuclear cisterna</p> Signup and view all the answers

    Which component of the nucleus is responsible for the exchange of substances with the cytoplasm?

    <p>Nuclear pores</p> Signup and view all the answers

    What characteristic of the nuclear envelope affects substance exchange?

    <p>It is impermeable to all ions and molecules</p> Signup and view all the answers

    In what form is DNA primarily found within the nucleus?

    <p>Condensed and uniformly distributed chromatin</p> Signup and view all the answers

    What type of staining causes nuclei to appear intensely stained in preparations?

    <p>Basic staining with hematoxylin</p> Signup and view all the answers

    What is the function of polyribosomes attached to the outer membrane of the nuclear envelope?

    <p>To produce proteins using mRNA</p> Signup and view all the answers

    What is the primary function of spindle fibers during mitosis?

    <p>To assist in chromosome alignment on the cell equator</p> Signup and view all the answers

    Which phase of mitosis is characterized by the separation of sister chromatids?

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

    What happens to the nuclear envelope during metaphase?

    <p>It disappears early in the phase</p> Signup and view all the answers

    In the absence of centrioles, what effect does this have on mitosis?

    <p>Microtubule-nucleating material disperses, affecting spindle formation</p> Signup and view all the answers

    What significant structural change occurs to chromosomes during telophase?

    <p>Chromosomes unwind into chromatin</p> Signup and view all the answers

    How do spindle fibers attach to chromosomes during metaphase?

    <p>At the centromere region via kinetochores</p> Signup and view all the answers

    What is the immediate outcome of sister chromatids aligning parallel to the equator?

    <p>They are prepared for separation during anaphase</p> Signup and view all the answers

    What initiates the development of the cleavage furrow during anaphase?

    <p>A change in the spindle/kinetochore attachment site</p> Signup and view all the answers

    What occurs to the mitotic spindle during telophase?

    <p>It disappears entirely</p> Signup and view all the answers

    Which type of chromatin do chromosomes reorganize into during telophase?

    <p>Interphase heterochromatin and euchromatin</p> Signup and view all the answers

    Which class of antibiotics primarily functions by inhibiting bacterial protein synthesis?

    <p>Tetracyclines and Macrolides</p> Signup and view all the answers

    What substance inhibits tRNA binding by acting on the 60S ribosomal subunit?

    <p>Shiga toxin</p> Signup and view all the answers

    What is the primary role of lysosomes in the cell?

    <p>Digesting phagocytosed material</p> Signup and view all the answers

    How are lysosomal enzymes produced?

    <p>Manufactured in the rough endoplasmic reticulum (rER)</p> Signup and view all the answers

    Which type of cytoplasmic inclusion is associated with patterns of cell activity?

    <p>Protein aggregates</p> Signup and view all the answers

    What is the physiological function of peroxisomes in cells?

    <p>Degradation of fatty acids and detoxification of harmful substances</p> Signup and view all the answers

    What condition is caused by the action of Diphtheria toxin on the ribosome?

    <p>Inhibition of protein synthesis leading to cell death</p> Signup and view all the answers

    What cellular structure is responsible for exporting digested products from lysosomes into the cytosol?

    <p>Lysosomal membrane carrier proteins</p> Signup and view all the answers

    Which of the following correctly correlates with the structure and function of a proteasome?

    <p>They degrade protein molecules into smaller peptides</p> Signup and view all the answers

    Which condition indicates the impact of lysosomal derangement on cellular health?

    <p>Accumulation of undigested substrates</p> Signup and view all the answers

    What is the primary role of contractile bundles formed by actin filaments?

    <p>Induce cleavage furrows during mitotic division</p> Signup and view all the answers

    Which cyclin is initially synthesized during the early G1 phase of the cell cycle?

    <p>Cyclin D</p> Signup and view all the answers

    What feature distinguishes the plus end of an actin filament?

    <p>It grows faster than the minus end</p> Signup and view all the answers

    Which complex allows the cell to exit the S phase during the cell cycle?

    <p>Cyclin A-CDK2</p> Signup and view all the answers

    Which functional form of actin provides structural support to the cell cortex?

    <p>Gel-like networks</p> Signup and view all the answers

    What is the main function of the cyclin B-CDK1 complex in the cell cycle?

    <p>To facilitate exit from the G2 phase into mitosis</p> Signup and view all the answers

    What is primarily formed by the organization of actin filament bundles?

    <p>The core structure of microvilli</p> Signup and view all the answers

    What is the role of N-terminal residues in determining protein half-lives?

    <p>They dictate the stability and turnover rate of the protein.</p> Signup and view all the answers

    Which statement regarding crystallins in the lens of the eye is true?

    <p>They were primarily synthesized during early development and have long half-lives.</p> Signup and view all the answers

    Which type of amino acid residues are considered destabilizing at the N-terminal for protein half-lives?

    <p>Arginine and acetylated alanine</p> Signup and view all the answers

    What is one of the primary functions of peroxisomes in the cell?

    <p>Beta-oxidation of long-chained fatty acids</p> Signup and view all the answers

    What can result from the failure of proteasomes to degrade misfolded proteins?

    <p>Accumulation of abnormal proteins leading to disease</p> Signup and view all the answers

    What is the primary reason for protein maturation in cells?

    <p>To activate proteins to functional forms and localize them</p> Signup and view all the answers

    How many high-energy phosphate bonds are hydrolyzed to charge tRNA with its amino acyl moiety?

    <p>2 high-energy bonds</p> Signup and view all the answers

    Which modification is specifically important for blood clotting?

    <p>γ-carboxylation of glutamic acid</p> Signup and view all the answers

    What is the function of molecular chaperones in protein maturation?

    <p>To assist in the folding of proteins into their 3D structures</p> Signup and view all the answers

    Which amino acid modifications are involved in collagen synthesis?

    <p>Hydroxylation of proline and lysine</p> Signup and view all the answers

    What happens to misfolded proteins during the process of protein maturation?

    <p>They are targeted for destruction</p> Signup and view all the answers

    Which type of glycosylation involves the attachment of carbohydrates to serine or threonine residues?

    <p>O-linked glycosylation</p> Signup and view all the answers

    What is the main outcome of translocating newly formed peptidyl-tRNA from the A site to the P site during translation?

    <p>Hydrolysis of one GTP to GDP</p> Signup and view all the answers

    Which of the following describes the role of signal peptides in protein maturation?

    <p>They are essential for the transport of proteins to their final destination</p> Signup and view all the answers

    What pathway do cyclins enter after performing their specific functions?

    <p>Ubiquitin-proteasome pathway</p> Signup and view all the answers

    Which factor does NOT stimulate a cell to enter the cell cycle?

    <p>Cellular dehydration</p> Signup and view all the answers

    What is the primary consequence of mutations in proto-oncogenes?

    <p>Uncontrolled cell proliferation</p> Signup and view all the answers

    Which mechanism does the cell NOT use to enforce checkpoints in the cell cycle?

    <p>Accelerating mitosis</p> Signup and view all the answers

    What structure attaches sister chromatids during cell division?

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

    Which condition can lead to an increased expression of proto-oncogenes?

    <p>Mechanical stretching</p> Signup and view all the answers

    What happens to oncogenes as a result of gene amplification?

    <p>Their activity is increased</p> Signup and view all the answers

    Which function is associated with the checkpoints in the cell cycle?

    <p>Ensuring adequate DNA synthesis</p> Signup and view all the answers

    Which of the following is NOT a direct result of cyclin degradation?

    <p>Activation of growth factors</p> Signup and view all the answers

    During mitosis, what characteristic is observed in chromosomes?

    <p>They become condensed and tightly coiled</p> Signup and view all the answers

    What is the term 'autophagy' derived from?

    <p>Self-devouring</p> Signup and view all the answers

    What structural element surrounds organelles during the autophagy process?

    <p>Elements of the endoplasmic reticulum</p> Signup and view all the answers

    What is primarily resistant to complete digestion in a lysosome?

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

    Which method allows degradation of senescent organelles in the cell?

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

    What initiates the formation of autophagosomes?

    <p>Autophagy-related genes</p> Signup and view all the answers

    What cellular conditions are known to activate autophagy?

    <p>Environmental stress</p> Signup and view all the answers

    Which type of vesicle is responsible for the transport of phagocytosed material?

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

    What is the fate of an autophagosome after it fully forms?

    <p>It fuses with a lysosome</p> Signup and view all the answers

    What is the primary material that remains after the degradation of lipids in lysosomes?

    <p>Residual bodies</p> Signup and view all the answers

    Which of the following best describes the role of autophagy in cellular processes?

    <p>Cellular waste management</p> Signup and view all the answers

    What role do microtubule-associated proteins (MAPs) play in cellular function?

    <p>They facilitate the translocation of organelles and vesicles.</p> Signup and view all the answers

    Which statement accurately describes the function of centrioles during cell division?

    <p>They assist in the formation of the spindle apparatus.</p> Signup and view all the answers

    How does colchicine exert its clinical effects on leukocytes?

    <p>By disrupting microtubule polymerization.</p> Signup and view all the answers

    Which of the following correctly describes the movement of motor proteins along microtubules?

    <p>Kinesin moves vesicles to the plus end, while dynein moves them to the minus end.</p> Signup and view all the answers

    What is the significance of the dynamic process of microtubule formation during cell division?

    <p>It allows for the symmetrically distributed daughter cells.</p> Signup and view all the answers

    Which of the following events occurs during the G1 phase of the cell cycle?

    <p>Synthesis of macromolecules essential for DNA replication</p> Signup and view all the answers

    What distinguishes the S phase of the cell cycle from the G2 phase?

    <p>The phase during which DNA replication occurs</p> Signup and view all the answers

    During which phase does the cell analyze DNA replication for errors before proceeding to mitosis?

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

    What occurs to centrioles during the cell cycle, specifically in the G1 phase?

    <p>Centrioles duplicate themselves</p> Signup and view all the answers

    What characterizes cells that have entered the G0 phase of the cell cycle?

    <p>They are temporarily resting before re-entering the cell cycle</p> Signup and view all the answers

    What is the primary role of molecular chaperones in protein maturation?

    <p>Aiding in the proper folding of proteins</p> Signup and view all the answers

    Which modification is crucial for the function of prothrombin in blood clotting?

    <p>γ-carboxylation of glutamic acid</p> Signup and view all the answers

    What process is described by the removal of amino terminal or signal peptides from proteins?

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

    Which of the following mechanisms is not directly involved in protein maturation?

    <p>Transcriptional regulation</p> Signup and view all the answers

    What is the result of errors during the translation process?

    <p>Misfolded proteins targeted for degradation</p> Signup and view all the answers

    What is the role of the sex chromatin in female cells?

    <p>It is genetically inactive.</p> Signup and view all the answers

    What distinguishes the appearance of sex chromatin in neutrophilic leukocytes?

    <p>It manifests as a drumstick-like appendage.</p> Signup and view all the answers

    What is the primary function of the nucleolus within the nucleus?

    <p>Production of ribosomal subunits.</p> Signup and view all the answers

    Which characteristic differentiates heterochromatin from euchromatin?

    <p>Heterochromatin is often visible as a clump in female cells.</p> Signup and view all the answers

    What component is commonly associated with the nucleolus, even though its functional significance is not well understood?

    <p>Heterochromatin.</p> Signup and view all the answers

    Study Notes

    Cell Cycle Control & Mitosis

    • The cell cycle is a series of events preparing a cell to divide into two daughter cells
    • Interphase includes three stages: G1 (growth), S (synthesis, DNA duplication), and G2 (preparations for mitosis)
    • Mitosis is a shorter period where the cell divides its nucleus and cytoplasm, producing two daughter cells
    • Cell growth occurs during G1 phase, restoring cell size to normal.
    • DNA is duplicated during S phase, doubling the cell's DNA complement.
    • G2 phase involves cell preparations for mitosis.

    Nucleus and Phases of Cell Cycle

    • The nucleus contains DNA blueprints for cell structures and activities
    • It contains molecular machinery for DNA replication and RNA synthesis (rRNA, mRNA, tRNA)
    • The nucleus does not produce proteins; it imports them from the cytoplasm
    • The nucleus has a nuclear envelope, chromatin, nucleolus and nuclear matrix
    • The nuclear envelope is made of two membranes making a perinuclear cisterna
    • Nuclear pores allow substance transport between the nucleus and cytoplasm
    • Chromatin is DNA wound around histone proteins (nucleosomes)
    • Heterochromatin is inactive/condensed, Euchromatin is active/less condensed
    • The nucleolus is involved in rRNA synthesis and ribosomal subunit assembly

    Cytoskeletal Microtubules & Microfilaments & Motility

    • The cytoskeleton is a protein meshwork in animal cells
    • The cytoskeleton supports cell shape, maintains cell structures, and allows cell movement and organelle transport
    • Microtubules are hollow tubes that act as intracellular pathways
    • Centrosomes are nucleation sites for microtubules
    • Microtubules are dynamic structures, rapidly changing length (growth/shrinkage)
    • Motor proteins (dynein and kinesin, MAPs) assist in organelle transport along microtubules
    • Microtubules are involved in cell division (spindle apparatus), cilia and flagella movement
    • Microfilaments (actin filaments) are thin filaments, with a plus (fast-growing) and minus (slow-growing) end.
    • Contractile bundles are an important type of microfilaments, moving organelles during cell division and activities
    • Microfilaments organize the cell cortex, provide microvilli support, and are focal points for cell-extracellular matrix interactions.

    Autophagy, Lysosomes, Peroxisomes & Cell Inclusions

    • Lysosomes are membrane-bound organelles containing hydrolytic enzymes for intracelluar digestion
    • Substances for degradation reach lysosomes through phagosomes, pinocytotic vesicles, and autophagosomes
    • Autophagy is a self-degredative process, removing damaged organelles, proteins, and other cellular components
    • Autophagy responds to stress and physiological conditions such as starvation, hyperthermia, and hypoxia.
    • Proteasomes are small organelles that degrade proteins.
    • Peroxisomes are organelles containing oxidative enzymes for specific metabolic processes.
    • Inclusions are non-living components of the cell like glycogen, lipids, pigments, that have no metabolic activity.

    Cell Cycle Control & Mitosis

    • The cell cycle is a tightly regulated process.
    • Cyclins and cyclin-dependent kinases (CDKs) control the cell cycle by ensuring that the cell cycle proceeds through its phases in an ordered and controlled way.
    • Checkpoints ensure that events are meticulously completed
    • Factors that cause cell entry into the cycle (example: mechanical force or injury to the tissue) can cause the release of ligands to the cell
    • Proto-oncogenes are genes that control the cell's proliferation, which must be very strictly regulated, so that uncontrolled cell proliferation does not happen
    • Mutations in proto-oncogenes lead to oncogenes which can cause cancer.

    Meiosis

    • Meiosis is a special type of cell division
    • It produces gametes (sex cells) with half the chromosome number of the parent cell.
    • Meiosis contains two phases: Meiosis I and Meiosis II.
    • Meiosis I involves reductional division, separating homologous chromosomes
    • Meiosis II involves equatorial division(similar to mitosis), separating sister chromatids
    • Meiosis ensures genetic variation through recombination (crossing over)
    • Results in four daughter cells with unique combinations of chromosomes.

    Gene Expression 2: RNA Transcription and Genetic Code

    • Translation is the process of converting mRNA codons into an amino acid sequence.
    • The genetic code defines the relationship between codons and amino acids.
    • The genetic code is degenerate, meaning multiple codons can code for the same amino acid.
    • mRNA, tRNA, rRNA and ribosomes are necessary for protein synthesis.
    • Initiation, elongation, and termination are the three main stages in the protein biosynthesis
    • Different translation initiation factors are necessary for eukaryotic cells
    • Specific aminoacyl-tRNA synthetases charge tRNA molecules with the appropriate amino acids
    • During protein elongation, the ribosome moves along the mRNA, adding amino acids to the growing polypeptide chain.
    • Stop codons signal termination of protein synthesis
    • Proteins undergo maturation to achieve their final, active form.

    Intercellular Junctions

    • Intercellular junctions are specialized areas where cells come in close contact with each other.
    • These structures are crucial for maintaining tissue integrity and function.
    • Anchoring junctions (zonula and macula adherens): Provide mechanical stability
    • Occluding junctions (zonula occludens) form an impermeable barrier.
    • Communicating junctions (gap junctions) allow small molecules to pass between cells.

    Protein Folding, and Post-translational Modification

    • Misfolded proteins are harmful, so cells have quality control mechanisms for proper protein folding (chaperones).
    • Proteins are post-translationally modified to activate/inactivate/regulate their function
    • Post translational modifications include proteolysis (cleavage), phosphorylation, glycosylation, and oxidation.

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