Cell Cycle and Chromosome Number
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Questions and Answers

What is the longest phase of the cell cycle?

  • Mitosis
  • Cytokinesis
  • Interphase (correct)
  • G2 stage

    • During which stage does DNA replication occur?

  • S stage (correct)
  • Mitosis
  • Cytokinesis
  • G1 stage

    • What is the diploid number of chromosomes for humans?

  • 23
  • 46 (correct)
  • 12
  • 92

    • What is the role of DNA helicase during DNA replication?

    <p>To separate the DNA strands (C)</p> Signup and view all the answers

    What are sister chromatids?

    <p>Identical copies of chromosomes joined at the centromere (A)</p> Signup and view all the answers

    Why can't mitosis produce gametes?

    <p>It keeps the number of chromosomes the same (D)</p> Signup and view all the answers

    What enzyme helps to assemble a DNA polymer during replication?

    <p>DNA polymerase (A)</p> Signup and view all the answers

    Which base pairs with adenine (A) during DNA replication?

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

    What is the result of semiconservative replication?

    <p>Each new double strand consists of one original strand and one newly assembled strand. (D)</p> Signup and view all the answers

    During which phase of the cell cycle is DNA replicated?

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

    Which phase of mitosis is characterized by the alignment of chromosomes at the cell's equatorial plane?

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

    What occurs during anaphase?

    <p>Spindles shorten and pull sister chromatids apart. (A)</p> Signup and view all the answers

    What is the primary change that occurs during telophase?

    <p>Nuclear membranes reform around separated chromosomes. (B)</p> Signup and view all the answers

    How does mitosis ensure daughter cells receive the correct number of chromosomes?

    <p>Each chromatid is joined to a centromere that pulls them apart. (C)</p> Signup and view all the answers

    What is the difference between a parent cell and a daughter cell that results from mitosis?

    <p>The daughter cell has undergone cytokinesis. (D)</p> Signup and view all the answers

    Which structure is responsible for anchoring spindle fibers during mitosis?

    <p>Centrioles (B)</p> Signup and view all the answers

    What is the longest phase of the cell cycle?

    <p>Interphase (B)</p> Signup and view all the answers

    What is the diploid number of chromosomes in human body cells?

    <p>46 (A)</p> Signup and view all the answers

    Which structure is formed during cytokinesis in plant cells?

    <p>Cell wall (B)</p> Signup and view all the answers

    Which of the following events happens first in the cell cycle?

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

    What is DNA helicase responsible for in DNA replication?

    <p>Unwinding the DNA double helix (D)</p> Signup and view all the answers

    Which phase of mitosis involves the alignment of chromosomes in the middle of the cell?

    <p>Metaphase (B)</p> Signup and view all the answers

    What is the role of DNA polymerase in DNA replication?

    <p>To synthesize new DNA strands (B)</p> Signup and view all the answers

    During which stage does cytokinesis occur in the cell cycle?

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

    If a parent cell has 46 chromosomes, how many chromosomes will each daughter cell have?

    <p>46 (A)</p> Signup and view all the answers

    What phase of the cell cycle is characterized by DNA replication?

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

    Which enzyme is responsible for assembling a DNA polymer during replication?

    <p>DNA polymerase (B)</p> Signup and view all the answers

    In which phase do chromatids line up at the center of the cell?

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

    What is the role of spindle fibers during Anaphase?

    <p>They shorten to pull sister chromatids apart. (A)</p> Signup and view all the answers

    What occurs during Telophase after the chromatids have separated?

    <p>New nuclear membranes form. (B)</p> Signup and view all the answers

    Which of the following statements is true about the resulting DNA strands after replication?

    <p>Each new double strand contains one original and one new strand. (C)</p> Signup and view all the answers

    What is the primary function of helicase in DNA replication?

    <p>To separate the DNA strands. (D)</p> Signup and view all the answers

    What structure must plant cells form during mitosis between the two nuclei?

    <p>Cytokinetic bridge (A)</p> Signup and view all the answers

    Which stage of mitosis is characterized by chromosomes being aligned in the center of the cell?

    <p>Metaphase (B)</p> Signup and view all the answers

    What is one key difference between a parent cell and a daughter cell following mitosis?

    <p>The daughter cell has the same amount of genetic material as the parent cell. (C)</p> Signup and view all the answers

    Which option correctly lists the first event in the cell cycle?

    <p>The chromosomes replicating (D)</p> Signup and view all the answers

    In which stage of mitosis do chromosomes unpair and the nuclear membrane reform?

    <p>Telophase (B)</p> Signup and view all the answers

    Which sequence accurately describes the events of mitosis?

    <p>Nuclear membrane dissolves; sister chromatids separate (B)</p> Signup and view all the answers

    Which of the following is NOT a phase of mitosis?

    <p>Cytokinesis (B)</p> Signup and view all the answers

    What is primarily ensured by the process of mitosis?

    <p>Daughter cells have the correct number and types of chromosomes (A)</p> Signup and view all the answers

    Study Notes

    The Cell Cycle

    • The cell cycle describes the stages of a single cell's life.
    • Interphase is the longest phase of the cell cycle.
    • The G1 stage is when the cell grows.
    • The S stage is when DNA replicates, doubling the genetic material in a cell.
    • The G2 stage is when the cell prepares to divide.
    • Mitosis is the nuclear division that produces an exact replica of the nucleus and all of its chromosomes.
    • Cytokinesis is the final stage of the cell cycle where the cytoplasm divides into two.

    Chromosome Number

    • Every species has a characteristic chromosome number, which is the number of chromosomes in its body cells, known as the diploid number.
    • To create two identical copies of itself, a cell must first duplicate its nucleus.
    • A parent cell with 46 chromosomes will produce two daughter cells, each with 46 chromosomes.
    • DNA replication occurs during the S phase of interphase, and is required for a cell to make a copy of itself.
    • Each chromosome consists of two DNA "arms" with a centromere in the center.
    • Replication produces an identical copy of each "arm," which are still joined at the centromere and are called sister chromatids, which remain joined until mitosis.

    DNA Replication

    • DNA replication is carried out by enzymes.
    • DNA polymerase helps assemble a DNA polymer.
    • DNA helicase binds to a site on the double-stranded DNA and begins to separate the two strands.
    • DNA polymerase moves along each strand, pairing free nucleotides to the nucleotides on the strand.
    • Complementary base pairing rules ensure new strands are identical to old strands (Adenine (A) with Thymine (T), Cytosine (C) with Guanine (G)).
    • Original DNA serves as a template for the new strand.
    • Semiconservative replication means each "new" double strand consists of one original strand and one newly assembled strand.

    Mitosis

    • DNA is replicated during the S phase.
    • Proteins are synthesized during the G2 phase.
    • Mitosis is the process of duplicating the nucleus, and consists of four phases: prophase, metaphase, anaphase, and telophase.

    Prophase

    • The nucleus disappears.
    • Chromosomes condense from chromatin.
    • Centrioles begin to move toward the poles.

    Metaphase

    • Centrioles produce spindle fibers.
    • Spindle fibers attach to the centromeres on the sister chromatids.
    • Chromatids line up in the center of the cell.

    Anaphase

    • Spindles shorten, pulling sister chromatids apart.
    • Chromatids from each pair move toward opposite poles.

    Telophase

    • New nuclear membranes form around the newly separated chromosomes.
    • Chromosomes unwind, becoming longer and thinner.

    Cytokinesis

    • Cytokinesis is the process in which the cytoplasm, organelles, and plasma membrane of a cell divide to form two daughter cells.
    • Plant cells must form a cell plate between the two nuclei during cytokinesis.

    How Mitosis Ensures Correct Chromosome Number

    • Each chromosome has replicated its DNA at the beginning of mitosis.
    • Two identical sister chromatids are joined at the centromere.
    • During metaphase, spindle fibers attach to the centromeres.
    • The fibers are anchored to centrioles at opposite ends of the cell.
    • When chromatids separate, each one is joined to one centromere.
    • The chromatids are pulled to opposite sides of the cell, and each one becomes part of one new nucleus.
    • This ensures each nucleus contains one copy of each chromosome.

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    Related Documents

    Lesson 12 - The Cell Cycle, DNA Replication, and Mitosis PDF

    Description

    Explore the essential stages of the cell cycle and understand the importance of chromosome number in cellular reproduction. This quiz covers interphase, mitosis, cytokinesis, and DNA replication, providing insights into how cells duplicate and divide. Test your knowledge on how these processes are fundamental to life.

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