Cell Division Types: Mitosis and Meiosis

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Questions and Answers

What occurs during telophase II in cell division?

  • Chromosomes decondense and a nuclear envelope reforms (correct)
  • DNA replicates and cytokinesis begins
  • Chromosomes condense and spindle fibers dissolve
  • Gametes undergo fertilization and form zygotes

Which of the following is NOT a significance of cell division?

  • Repairing damaged tissues
  • Increasing metabolic rate in existing cells (correct)
  • Growth and development of organisms
  • Asexual reproduction

What mechanism do cyclins and cyclin-dependent kinases (CDKs) utilize in regulating the cell cycle?

  • They inhibit cell division at all times
  • They activate the cell cycle progression through fluctuations (correct)
  • They degrade damaged DNA to prevent cell division
  • They fluctuate levels to activate checkpoints

How does meiosis contribute to genetic diversity?

<p>Through crossing over and independent assortment (A)</p> Signup and view all the answers

Which statement describes a consequence of dysregulation of the cell cycle?

<p>Formation of tumors due to uncontrolled cell division (A)</p> Signup and view all the answers

What is the main purpose of mitosis?

<p>To generate genetically identical cells for growth and repair (D)</p> Signup and view all the answers

Which phase of the cell cycle occurs before mitosis?

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

What are the daughter cells produced by meiosis characterized as?

<p>Haploid and genetically unique (C)</p> Signup and view all the answers

Which phase of meiosis involves homologous chromosomes pairing up?

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

In which phase do sister chromatids separate during mitosis?

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

Which process adds genetic variation during meiosis?

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

What is the correct sequence of phases in mitosis?

<p>Prophase, Metaphase, Anaphase, Telophase (D)</p> Signup and view all the answers

What is formed at the end of Meiosis II?

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

Flashcards

Telophase II

The final stage of meiosis II, where chromosomes decondense, nuclear envelopes reform around the separated chromosomes, and the cytoplasm divides, resulting in four haploid daughter cells.

Cell division

A process that is essential for the growth, development, tissue repair, and reproduction of organisms.

Cyclins and CDKs

Proteins that play a crucial role in regulating the cell cycle, ensuring that it progresses in an orderly manner.

Checkpoints

Control points in the cell cycle that ensure everything is proceeding smoothly; if problems are detected, the cycle can be paused or stopped.

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Cancer

A disease characterized by uncontrolled cell division, which can lead to the formation of tumors.

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What is cell division?

Cell division is the process by which a single cell divides into two or more daughter cells. This is essential for growth, repair, and reproduction in all living organisms.

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What is mitosis?

Mitosis is a type of cell division that produces two genetically identical diploid daughter cells from a single diploid parent cell. It's crucial for growth and repair in somatic cells (non-reproductive cells).

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What is meiosis?

Meiosis is a type of cell division that produces four genetically unique haploid daughter cells from a single diploid parent cell. It's essential for sexual reproduction, resulting in gametes (sperm and egg).

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What happens during interphase?

Interphase is the period of the cell cycle before mitosis, where the cell grows, replicates its DNA, and prepares to divide.

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What happens during prophase?

Prophase is the first stage of mitosis where chromosomes condense becoming visible, the nuclear envelope breaks down, and spindle fibers form.

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What happens during metaphase?

Metaphase is the stage of mitosis where chromosomes align in the middle of the cell (metaphase plate).

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What happens during anaphase?

Anaphase is the stage of mitosis where sister chromatids separate and move to opposite poles of the cell.

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What happens during telophase?

Telophase is the final stage of mitosis where chromosomes decondense, a nuclear envelope reforms around each set of chromosomes, and the cell begins to divide.

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Study Notes

Cell Division

  • Cell division is the process where a single cell divides into two or more daughter cells, crucial for growth, repair, and reproduction.

Types of Cell Division

  • Mitosis: Produces two genetically identical diploid daughter cells from a single diploid parent cell, vital for somatic cell growth and repair.
    • Key phases: Prophase, Metaphase, Anaphase, Telophase.
    • Result: Two identical diploid daughter cells.
  • Meiosis: Produces four genetically unique haploid daughter cells from a single diploid parent cell, critical for sexual reproduction, forming gametes (sperm and egg).
    • Two rounds of division: Meiosis I and Meiosis II.
    • Result: Four unique haploid daughter cells.

Mitosis

  • Interphase: The cell cycle period before mitosis, where the cell grows, replicates its DNA, and prepares to divide.
    • Subphases: G1, S, and G2 phase.
  • Prophase: Chromosomes condense becoming visible, nuclear envelope breaks down, and spindle fibers form.
  • Metaphase: Chromosomes align at the cell's equator (metaphase plate).
  • Anaphase: Sister chromatids separate and move to opposite poles of the cell.
  • Telophase: Chromosomes decondense, nuclear envelope reforms, and cell division begins.
  • Cytokinesis: Cytoplasm divides, forming two separate daughter cells.

Meiosis

  • Meiosis I: The first division, separating homologous chromosomes.
    • Prophase I: Homologous chromosomes pair up (synapsis), exchange genetic material (crossing over), a key source of genetic variation.
    • Metaphase I: Homologous pairs align at the metaphase plate. Independent assortment occurs, further increasing genetic diversity.
    • Anaphase I: Homologous chromosomes separate and move to opposite poles.
    • Telophase I: Chromosomes decondense, nuclear envelope may reform, and cell division starts. Cytokinesis forms two haploid daughter cells.
  • Meiosis II: The second division, similar to mitosis, separating sister chromatids.
    • Prophase II: Chromosomes condense, nuclear envelope breaks down (if reformed).
    • Metaphase II: Chromosomes align at the metaphase plate.
    • Anaphase II: Sister chromatids separate and move to opposite poles.
    • Telophase II: Chromosomes decondense, nuclear envelope reforms, and cytokinesis forms four haploid daughter cells.

Significance of Cell Division

  • Growth and Development: Critical for organisms to grow larger and develop from a single fertilized egg.
  • Tissue Repair and Replacement: Essential for repairing damaged tissues and replacing old cells.
  • Asexual Reproduction: Some organisms reproduce asexually via cell division, producing genetically identical offspring.
  • Sexual Reproduction: Essential for creating gametes (sperm and egg), which combine to form genetically unique offspring.
  • Genetic Diversity: Meiosis, through crossing over and independent assortment, creates genetic variation among offspring, vital for adaptation and evolution.

Regulation of Cell Division

  • Cyclins and Cyclin-Dependent Kinases (CDKs): Proteins regulating cell cycle progression. Cyclin levels fluctuate, activating CDKs.
  • Checkpoints: Control points in the cell cycle. Errors (DNA damage) halt the cycle.
  • Cancer: Uncontrolled cell division leading to tumors. Dysregulation of cell cycle control is a major cancer factor.

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