Human Genetics Cell Cycle Quiz
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Questions and Answers

What occurs during metaphase in cell division?

  • Cytokinesis initiates with membrane furrowing
  • Separation of sister chromatids
  • Nuclear envelope reformation around chromosomes
  • Chromosomes align at the metaphase plate (correct)

Which microtubules are responsible for directing chromosome movement toward the centrosomes?

  • Kinetochore microtubules (correct)
  • Astral microtubules
  • Cytoplasmic microtubules
  • Polar microtubules

What is the result of cytokinesis in the cell cycle?

  • Creation of two genetically identical daughter cells (correct)
  • Alignment of chromosomes at the spindle equator
  • Development of gametes
  • Formation of the mitotic spindle

During which phase does the breakdown of proteins holding sister chromatids together occur?

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

What happens to chromosomes during telophase?

<p>They reconfigure into chromatin and a nuclear envelope reappears (D)</p> Signup and view all the answers

How does meiosis differ from mitosis regarding chromosome number?

<p>Meiosis results in cells with half the number of chromosomes (B)</p> Signup and view all the answers

What structure forms during cytokinesis in animal cells?

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

What is the DNA content of daughter cells after mitosis?

<p>2n DNA content (D)</p> Signup and view all the answers

What is the primary outcome of meiosis I with respect to chromosome number?

<p>Chromosome number is reduced to haploid (1n) (D)</p> Signup and view all the answers

During which phase of meiosis I do homologous chromosomes form bivalents?

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

In meiosis I, what happens during Anaphase I?

<p>Homologous chromosomes separate, but sister chromatids remain together (A)</p> Signup and view all the answers

What significant event occurs during Pachytene in Prophase I?

<p>Crossing over occurs between homologous chromosomes (C)</p> Signup and view all the answers

What is the status of chromatids in Telophase I?

<p>Sister chromatids remain attached at the centromere (C)</p> Signup and view all the answers

What does cytokinesis result in after meiosis I?

<p>Two haploid cells (B)</p> Signup and view all the answers

What is the amount of DNA present immediately after the completion of meiosis I?

<p>2d (A)</p> Signup and view all the answers

Which phase aligns chromosomes along the equatorial plate during meiosis I?

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

What occurs during the S phase of the cell cycle?

<p>DNA is replicated and chromatids are formed. (D)</p> Signup and view all the answers

What best describes the G2 phase of the cell cycle?

<p>Cell growth and DNA inspection for preparation of division. (B)</p> Signup and view all the answers

Which statement about mitosis is true?

<p>The process ensures two identical daughter cells are produced. (D)</p> Signup and view all the answers

What is the role of the kinetochore during mitosis?

<p>To anchor chromatids for proper separation. (D)</p> Signup and view all the answers

What does cytokinesis accomplish?

<p>Distribution of nonnuclear organelles into daughter cells. (C)</p> Signup and view all the answers

Which phase follows the S phase in the cell cycle?

<p>G2 phase. (C)</p> Signup and view all the answers

During which stage of mitosis do chromosomes become visible?

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

How long can the G2 phase last in some cells?

<p>May last indefinitely or up to 1 hour. (D)</p> Signup and view all the answers

Flashcards

Metaphase

Phase of mitosis where chromosomes align at the cell's center (metaphase plate).

Kinetochore microtubules

Microtubules that attach to chromosomes and pull them to opposite poles during mitosis.

Anaphase

Phase of mitosis where sister chromatids separate and move to opposite poles.

Telophase

Phase of mitosis where new nuclei form around separated chromosomes, and the cell begins to divide.

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Cytokinesis

Physical division of the cytoplasm to create two daughter cells after mitosis or meiosis.

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Diploid (2n)

Having two sets of chromosomes (one set from each parent).

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Meiosis

Cell division that produces gametes (sex cells) with half the chromosomes of somatic cells.

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Somatic cell

Any cell of the body except gametes.

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Synapsis

The pairing of homologous chromosomes during prophase I of meiosis.

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Tetrads

A group of four chromatids formed by two homologous chromosomes that have paired up during synapsis.

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Crossing Over

The exchange of genetic material between homologous chromosomes during prophase I of meiosis.

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Chiasmata

The points where homologous chromosomes are still connected after crossing over.

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Random Assortment

The random distribution of maternal and paternal chromosomes during meiosis.

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Equatorial Division

A cell division where the number of chromosomes remains the same, like in meiosis II.

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Karyokinesis

The division of the nucleus during mitosis, where chromosomes are segregated and distributed equally to daughter cells.

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Chromatid

One of two identical copies of a replicated chromosome, joined at the centromere.

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Kinetochore

A protein complex that assembles on a chromosome, providing a point of attachment for microtubules during cell division.

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Study Notes

Human Genetics

  • Study material for 3rd Stage Medical Laboratory Techniques students at Al-Salam University, Baghdad, Iraq.
  • Content covers cell cycle checkpoints, cell cycle, mitosis, and meiosis.

Cell Cycle Checkpoints

  • Control mechanisms ensuring proper cell cycle progression.
  • Assess cell conditions at each checkpoint.
  • Major checkpoints: G1 (Start/Restriction), G2/M, and Metaphase-to-Anaphase.
  • Progression through checkpoints determined by cyclin-dependent kinases (CDKs).
  • Different cyclin forms produced at each cell cycle stage to control specific events.

Cell Cycle and Checkpoints

  • Stages: G1, S, G2, and M (Mitosis)
  • G1 Checkpoint: Occurs towards the end of G1 phase. Ensures cell size, protein synthesis are appropriate for DNA replication prior to S phase.
  • DNA Synthesis Checkpoint: Occurs during the S phase. Checks correctness of DNA replication.
  • Mitosis Checkpoint: During the M phase. Ensures mitosis is complete before cell division.

Phases of Cell Cycle

  • Interphase: Cell growth and chromosome copying.
  • Mitotic (M) phase: Includes mitosis and cytokinesis.
  • Interphase subdivided further into G1, S, and G2 phases
    • G1 phase: The longest and variable phase. Cells gather nutrients, synthesize RNA and proteins, prepare for DNA replication.
    • S phase: DNA replication. Cell DNA content doubles.
    • G2 phase: Cell prepares for division. Cell growth, checks replicated DNA.

Mitosis

  • Cell division that increases cell number, permits renewal of cell populations, and allows wound repair.
  • Karyokinesis (nuclear division) and cytokinesis (cytoplasm division).
  • Phases of Mitosis:
    • Prophase: Chromatin condenses, nuclear envelope disappears.
    • Metaphase: Chromosomes align at the metaphase plate.
    • Anaphase: Sister chromatids separate and move to opposite poles.
    • Telophase: Chromosomes decondense, nuclear envelope reforms, cytokinesis begins.
    • Cytokinesis: Completion of cell division producing two daughter cells.

Meiosis

  • Two sequential nuclear divisions producing gametes (sex cells).

  • Reduced chromosome number to half the parent cell's.

  • Haploid gametes combine during fertilization to form a diploid zygote.

  • Gametes (e.g., sperm and egg) have one copy of each chromosome.

  • Meiosis I: Reductional division (chromosome number reduction).

    • Stages of Meiosis I: Prophase I (with 5 substages: Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis), Metaphase I, Anaphase I, Telophase I.

  • Meiosis II: Equational division (sister chromatids separate).

    • Stages of Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II.

  • Differences in meiosis between males and females.

  • Male: Results in 4 genetically different haploid spermatids that differentiate into spermatozoa.

  • Female: Results in one ovum and 3 polar bodies, which degenerate.

  • Meiosis and genetic variability.

  • Random assortment and crossing over result in genetically unique gametes.

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Human Genetics PDF - Lec 3 and 4 - 3rd Stage

Description

This quiz is tailored for 3rd Stage Medical Laboratory Techniques students at Al-Salam University, Baghdad. It covers essential concepts like cell cycle checkpoints, mitosis, and meiosis, ensuring a thorough understanding of cell cycle progression and its control mechanisms.

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