Cell Division and Chromosome Theory Quiz
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Questions and Answers

Which stage of meiosis involves the maximum condensation of chromosomes?

  • Metaphase I (correct)
  • Prophase I
  • Telophase I
  • Anaphase II

    • Chiasmata are the points where homologous chromosomes are drawn apart during diplotene.

    False

    How many products are formed from one parent cell after meiosis?

    Four

    The process of pairing homologous chromosomes begins in __________.

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

    Match the following stages of meiosis with their characteristics:

    <p>Leptotene = Thin thread-like chromosomes Pachytene = Bivalents are formed and pairing is stabilized Diakinesis = Short thick cross-shaped configurations Metaphase I = Alignment of bivalents in the equatorial plane</p> Signup and view all the answers

    What is the main outcome of meiosis?

    <p>Four haploid cells</p> Signup and view all the answers

    Metaphase I is referred to as the reductional division.

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

    During __________, the nuclear membrane and nucleolus disappear.

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

    What happens to the nuclear envelope during prophase?

    <p>It breaks up into small vesicles</p> Signup and view all the answers

    Maximum condensation of chromatin occurs during metaphase.

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

    What enzyme is thought to play a role in chromosome condensation during metaphase?

    <p>topoisomerase II</p> Signup and view all the answers

    Each chromosome consists of two _______ during metaphase.

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

    What is the function of the kinetochore?

    <p>To attach microtubules for movement</p> Signup and view all the answers

    The centromere divides longitudinally during telophase.

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

    Match the following components with their respective functions:

    <p>Centromere = Region of central constriction on each chromosome Chromatids = Identical halves of a chromosome Kinetochore = Site of microtubule attachment Microtubules = Fibers that pull chromatids apart</p> Signup and view all the answers

    Misalignment of chromosomes in the equatorial region may _______ cells at metaphase.

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

    What type of gene is responsible for the segregation distorter (SD) mutation in Drosophila males?

    <p>Dominant gene on chromosome II</p> Signup and view all the answers

    Drosophila males experience crossing over in meiosis.

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

    What effect does the recovery disrupter (RD) mutation have on male Drosophila?

    <p>It causes fragmentation of Y-bearing sperm, resulting in an excess of female flies in the progeny.</p> Signup and view all the answers

    The microtubules in the spindle apparatus are assembled from __________ proteins.

    <p>α and β tubulin</p> Signup and view all the answers

    Match the following mutations with their effects:

    <p>Segregation Distorter (SD) = Transmits mutant gene to 50% of progeny Recovery Disrupter (RD) = Causes fragmentation of Y-bearing sperm mei-S8 = Causes nondisjunction in females mei-218 = Reduces recombination or interferes with chromosome segregation</p> Signup and view all the answers

    Which stage of meiosis is primarily affected by most meiotic mutants in Drosophila?

    <p>Meiosis I</p> Signup and view all the answers

    Spindle fibers are composed of microtubules that have a diameter of 20 nm.

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

    What are the smaller circles observed in the cross section of a microtubule called?

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

    Which protein kinase is responsible for phosphorylating tyrosine-15 on Cdc2?

    <p>Wee1</p> Signup and view all the answers

    Cdc2 kinase activity is activated through the phosphorylation of tyrosine-15.

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

    What process degrades cyclin B and inactivates Cdc2?

    <p>Ubiquitin-mediated proteolysis</p> Signup and view all the answers

    The transition from G1 to S phase is regulated by Cdk2 and Cdk4 in association with cyclins _____ and _____.

    <p>D, E</p> Signup and view all the answers

    Match the following Cdk proteins with their associated phases:

    <p>Cdk1 = G2 to M phase Cdk2 = G1 to S phase Cdk4 = G1 restriction point Cdk6 = G1 progression</p> Signup and view all the answers

    Which of the following describes the role of Cdc25 in the cell cycle?

    <p>It dephosphorylates threonine-14 and tyrosine-15 of Cdc2.</p> Signup and view all the answers

    Cdks are only controlled by cyclin associations and have no other regulatory mechanisms.

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

    What is the original member of the Cdk family known as?

    <p>Cdk1</p> Signup and view all the answers

    What is the role of D-type cyclins in cell cycle progression?

    <p>They regulate progression through the restriction point in late G1.</p> Signup and view all the answers

    Growth factors must be present throughout G1 for cells to progress through the restriction point.

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

    What happens to cells when growth factors are removed prior to G1?

    <p>Cells become quiescent or enter G0.</p> Signup and view all the answers

    Defects in cyclin D regulation contribute to the loss of growth regulation characteristic of _____.

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

    Match the following cyclin-related components with their functions:

    <p>Cdk/cyclin complex = Regulates cell cycle progression Cdk inhibitors (CkIs) = Inhibits Cdk activity Rb protein = Regulates progression through G1 D-type Cyclins = Induced in response to growth factors</p> Signup and view all the answers

    Which of the following is a key substrate protein of Cdk4, 6/cyclin D complexes?

    <p>Rb protein</p> Signup and view all the answers

    Mutations leading to continuous expression of cyclin D1 are unrelated to human cancers.

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

    What are the consequences of phosphorylating the Cdc threonine residue at position 160?

    <p>Activation of Cdk/cyclin complex.</p> Signup and view all the answers

    What percentage of cells showed the unpaired chromosome passing to one pole with the larger homologue in grasshoppers?

    <p>50%</p> Signup and view all the answers

    Boveri's work on sea urchins contradicted Blakeslee's findings with Datura.

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

    What is the normal diploid chromosome number in Datura?

    <p>24</p> Signup and view all the answers

    T.H. Morgan demonstrated that the gene for white eye color in Drosophila was linked to the ______.

    <p>sex chromosome</p> Signup and view all the answers

    Match the scientists with their contributions:

    <p>Carothers = Studied grasshopper chromosomes Boveri = Explored chromosomes in sea urchins Blakeslee = Worked with Datura Sutton = Contributed to the Sutton-Boveri theory</p> Signup and view all the answers

    Which of the following is NOT one of the characteristic features of chromosomes as discovered by Boveri and Sutton?

    <p>Chromosome replication occurs at the same rate</p> Signup and view all the answers

    Each of the 12 plant types in Datura had morphologically identical fruit capsules.

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

    What phenomenon describes the inability of Mendel's law of independent assortment to apply to some genes?

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

    Study Notes

    Cell Division and Chromosome Theory of Inheritance

    • The cell cycle is the period from a cell's formation by division to its next division. It has four phases: G1, S, G2, and M (mitosis or meiosis).
    • Interphase comprises G1, S, and G2 phases.
    • DNA synthesis occurs during the S phase. Protein synthesis occurs throughout interphase.
    • Mitosis is the division of somatic (body) cells in diploid organisms.

    Mitosis Stages

    • Prophase: Chromatin condenses into chromosomes. The nucleolus and nuclear membrane disappear.
    • Metaphase: Chromosomes align along the metaphase plate (equatorial plate).
    • Anaphase: Sister chromatids separate and move to opposite poles.
    • Telophase: Chromosomes decondense. Nuclear membrane and nucleolus reform.

    Meiosis

    • Meiosis is cell division in germ cells (sex cells) resulting in four haploid cells.
    • Meiosis requires two divisions, meiosis I and II.

    Meiosis I Stages

    • Leptotene: Chromosomes become visible as long, thin threads.
    • Zygotene: Homologous chromosomes begin to pair. Synapsis occurs (pairing).
    • Pachytene: Chromosomes condense further, and crossing over occurs.
    • Diplotene: Homologous chromosomes begin to separate, held together at chiasmata (sites of crossing over).
    • Diakinesis: Chromosomes condense further. Nuclear membrane and nucleolus break down.
    • Metaphase I: Homologous chromosome pairs align along the metaphase plate.
    • Anaphase I: Homologous chromosomes separate and move to opposite poles.
    • Telophase I: Chromosomes reach the poles. Nuclear envelope may reform. Cytokinesis occurs.

    Meiosis II Stages

    • This division is similar to mitosis. Meiosis II separates sister chromatids.

    Cytokinesis

    • In animal cells, a cleavage furrow forms.
    • In plant cells, a cell plate forms.

    Regulation of the Cell Cycle

    • Cell cycle progression is regulated by checkpoints.
    • Checkpoints ensure completion of each phase before the next.
    • Checkpoints detect and repair DNA damage.
    • Growth factors regulate progression through the cell cycle.
    • Cyclins are proteins that activate cyclin-dependent kinases (Cdks).
    • Cdk activity regulates cell cycle progression through phosphorylation.

    Chromosome Theory of Inheritance

    • Chromosomes carry hereditary information (genes).
    • Homologous chromosomes have similar genetic information but may have different alleles.
    • Chromosomes segregate during meiosis, maintaining genetic diversity.

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    Cell Division and Chromosome Theory of Inheritance PDF

    Description

    Test your knowledge on the cell cycle, mitosis, and meiosis. This quiz covers the phases of mitosis and the stages of meiosis, including key processes involved in cell division. Perfect for biology students looking to enhance their understanding of genetic inheritance.

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