Cell Cycle and Chromosome Structure
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Questions and Answers

Which of the following correctly defines diploid cells?

  • Cells with pairs of homologous chromosomes (correct)
  • Cells with one complete set of chromosomes from one parent
  • Cells that undergo binary fission
  • Cells containing one set of unpaired chromosomes
  • What is the role of the kinetochore during mitosis?

  • Separates the sister chromatids
  • Stabilizes the telomere
  • Facilitates spindle microtubule attachment (correct)
  • Duplicates the chromosomes
  • What is the primary event that occurs during the cell cycle?

  • Nuclear membrane breakdown
  • Replication of DNA (correct)
  • Formation of a septum
  • Binary fission
  • What distinguishes a normal human karyotype?

    <p>It contains 23 pairs of chromosomes.</p> Signup and view all the answers

    During what phase does cytokinesis occur?

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

    Which phase of the cell cycle is primarily associated with DNA synthesis?

    <p>Synthesis phase (S)</p> Signup and view all the answers

    During which phase of mitosis do chromosomes align at the metaphase plate?

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

    What occurs during the anaphase stage of mitosis?

    <p>Separation of sister chromatids</p> Signup and view all the answers

    What is the primary role of cytokinesis in cell division?

    <p>Splitting of the cytoplasm to produce daughter cells</p> Signup and view all the answers

    In which type of cell does the absence of centrosomes during mitosis require the dependence on enzymes for spindle fiber organization?

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

    Study Notes

    Chromosome Structure

    • Chromosomes are composed of DNA and proteins
    • Sister chromatids are identical copies of a chromosome, connected at the centromere
    • Telomeres are protective caps at the ends of chromosomes, preventing degradation
    • Kinetochores are protein structures at the centromere where spindle fibers attach

    Eukaryotic Cell Cycle

    • The cell cycle is a series of events leading to cell growth, DNA replication, and division
    • Two main phases: Interphase and Mitotic (M) phase
    • Interphase is the longest phase, divided into G1, S, and G2 phases
    • G1 phase: Cell growth and normal metabolic activities
    • S phase: DNA replication and duplication of chromosomes
    • G2 phase: Preparation for mitosis, including protein synthesis
    • M phase includes mitosis and cytokinesis

    Prokaryotic Cell Cycle

    • Prokaryotic cells divide by binary fission
    • DNA replication, growth, and division occur without distinct phases
    • No spindle apparatus or nuclear membrane involvement
    • Replication occurs in the cytoplasm

    Mitosis

    • Division of the nucleus and cytoplasm, resulting in two genetically identical daughter cells
    • Ensures the accurate distribution of chromosomes to daughter cells
    • Occurs in somatic cells for growth and repair

    Mitosis Stages

    • Prophase: Chromosomes condense, nuclear envelope breaks down, mitotic spindle forms
    • Metaphase: Chromosomes line up at the metaphase plate, attached to spindle fibers
    • Anaphase: Sister chromatids separate and move towards opposite poles
    • Telophase: Chromosomes reach poles, nuclear envelope reforms around each set, chromosomes decondense
    • Cytokinesis: Division of the cytoplasm, forming two daughter cells

    Cytokinesis in Animal and Plant Cells

    • Animal Cells: Cleavage furrow forms, pinching the cell membrane inwards
    • Plant Cells: Cell plate forms between the daughter nuclei, eventually becoming a new cell wall

    Meiosis

    • Division of the nucleus resulting in four genetically unique daughter cells, each having half the number of chromosomes as the parent cell
    • Occurs in germ cells for sexual reproduction
    • Involves two rounds of division: Meiosis I and Meiosis II

    Meiosis I

    • Prophase I: Homologous chromosomes pair up (synapsis) and exchange genetic material (crossing over)
    • Metaphase I: Paired homologous chromosomes align at the metaphase plate
    • Anaphase I: Homologous chromosomes separate, moving to opposite poles
    • Telophase I: Two daughter cells form, each with half the number of chromosomes

    Meiosis II

    • Similar to mitosis, but with half the number of chromosomes
    • Prophase II: Chromosomes condense, nuclear envelope breaks down, spindle fibers form
    • Metaphase II: Chromosomes align at the metaphase plate
    • Anaphase II: Sister chromatids separate, moving to opposite poles
    • Telophase II: Four daughter cells form, each haploid (n)

    Comparison of Mitosis and Meiosis

    • Mitosis produces two diploid (2n) daughter cells; meiosis produces four haploid (n) daughter cells
    • DNA replicates once in interphase before both mitosis and meiosis I; no replication before meiosis II
    • Crossing over happens in prophase I of meiosis but not in mitosis or meiosis II
    • Metaphase I of meiosis has paired homologous chromosomes aligning, whereas mitosis has individual chromosomes aligning
    • Anaphase I involves the separation of homologous chromosomes, while anaphase in mitosis separates sister chromatids

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    Description

    This quiz covers the fundamental concepts of chromosome structure, including sister chromatids, telomeres, and kinetochores. Additionally, it explores the eukaryotic and prokaryotic cell cycles, highlighting important phases like interphase and mitosis. Test your knowledge on these essential biological processes.

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