Meiosis Flashcards
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Questions and Answers

What happens during Prophase 1 (early)?

DNA condenses, chromosomes become visible.

What occurs in Prophase 1 (late)?

Homologous chromosomes pair up and form tetrads; crossing-over occurs at points called 'chiasmata.'

What occurs during Metaphase 1?

Homologous chromosomes (tetrads) line up along the equator.

Describe the process that happens in Anaphase 1.

<p>Spindle fibers separate each of the homologous chromosomes to opposite sides of the cell.</p> Signup and view all the answers

What occurs in Telophase 1?

<p>Cytoplasm divides, two smaller daughter cells are formed.</p> Signup and view all the answers

What happens during Prophase II?

<p>Chromosomes condense and become visible; nuclear membrane dissolves and spindle fibers re-appear.</p> Signup and view all the answers

What occurs in Metaphase II?

<p>Chromosomes line up along the equator; they are not in homologous pairs.</p> Signup and view all the answers

What happens during Anaphase II?

<p>Chromatids of each chromosome separate and move to each end of the cell.</p> Signup and view all the answers

What occurs in Telophase II?

<p>Nuclear membrane reforms, cytoplasm divides; in total 4 haploid daughter cells are formed.</p> Signup and view all the answers

What is the first division of meiosis called?

<p>Reduction division.</p> Signup and view all the answers

What occurs in the second division of meiosis?

<p>Splits the two chromatids on each chromosome so that each daughter cell has one chromatid per chromosome.</p> Signup and view all the answers

Define mitosis.

<p>The division of the nucleus of a cell into two daughter nuclei.</p> Signup and view all the answers

What is Interphase?

<p>The phase of the cell cycle where growth, synthesis of new DNA, and organelles takes place.</p> Signup and view all the answers

What happens during G1 phase?

<p>Cell is smallest in size and grows during this phase. After this phase, there is a checkpoint to see if the cell is ready to move on to the next step.</p> Signup and view all the answers

What occurs during S Phase?

<p>Each of the 46 chromosomes (DNA) is duplicated/synthesized.</p> Signup and view all the answers

What occurs during the G2 phase?

<p>Last growth phase of the cell cycle. After this phase, there is a checkpoint to see if the cell is ready to move on to the next step.</p> Signup and view all the answers

What is prophase in mitosis?

<p>The phase where the chromosomes become visible as a pair of sister chromatids joined at the centromere.</p> Signup and view all the answers

What occurs during metaphase in mitosis?

<p>The phase where the chromosomes line up at the metaphase plate and attach to the microtubules at the kinetochore.</p> Signup and view all the answers

What occurs during anaphase in mitosis?

<p>The stage when the sister chromatids are pulled apart and towards opposite poles of the nuclear spindle.</p> Signup and view all the answers

What is telophase in mitosis?

<p>Final phase where chromatids reach opposite poles and are now called chromosomes again; the nuclear membrane reforms.</p> Signup and view all the answers

Define cytokinesis.

<p>The division of the cell cytoplasm to form two new cells.</p> Signup and view all the answers

What is a centrosome?

<p>Consists of 2 centrioles arranged at right angles of one another; centrosomes are at each pole and help the cell divide.</p> Signup and view all the answers

What is a spindle?

<p>A structure consisting of microtubules found in eukaryotic cells during cell division.</p> Signup and view all the answers

Define a chromosome.

<p>A linear DNA molecule wrapped around histone proteins found in the nucleus.</p> Signup and view all the answers

What is a chromatid?

<p>A replicated chromosome appears as two strands in early stages of cell division; each strand is a chromatid.</p> Signup and view all the answers

What is a centromere?

<p>The region of a chromosome where two sister chromatids are joined together and where the spindle fiber attaches during cell division.</p> Signup and view all the answers

What are cyclins?

<p>Proteins that control the progress of the cell cycle.</p> Signup and view all the answers

Define carcinoma.

<p>Cancerous tumor.</p> Signup and view all the answers

What is metastasis?

<p>The spread of cancer cells beyond their original site.</p> Signup and view all the answers

What is a mutagen?

<p>A chemical or physical agent that interacts with DNA and causes a mutation.</p> Signup and view all the answers

What defines an oncogene?

<p>Cancer-causing genes that are formed due to mutations.</p> Signup and view all the answers

What is a kinetochore?

<p>The structure that attaches the spindle fibers to the centromere.</p> Signup and view all the answers

What is independent assortment?

<p>The random assortment of chromosomes and combinations of chromosomes in meiosis.</p> Signup and view all the answers

Study Notes

Cell Division Overview

  • Meiosis consists of two divisions: Meiosis I (reduction division) and Meiosis II.
  • Each phase of meiosis prepares chromosomes for the process of separation and ultimately results in four haploid daughter cells.

Meiosis Stages

  • Prophase I (Early)

    • DNA condenses, and chromosomes become visible.

  • Prophase I (Late)

    • Homologous chromosomes pair up to form a tetrad.
    • Crossing-over occurs at chiasmata, allowing genetic variation.

  • Metaphase I

    • Tetrads align along the equator of the cell.

  • Anaphase I

    • Spindle fibers pull homologous chromosomes apart to opposite poles of the cell.

  • Telophase I

    • Cytoplasm divides, leading to the formation of two smaller daughter cells.

  • Prophase II

    • Chromosomes condense, becoming visible again. The nuclear membrane dissolves, and spindle fibers reappear.

  • Metaphase II

    • Chromosomes (each with two chromatids) line up along the equator without homologous pairs.

  • Anaphase II

    • Sister chromatids are separated and move towards opposite ends of the cell.

  • Telophase II

    • Nuclear membranes reform, cytoplasm divides, resulting in four haploid daughter cells.

Mitosis Process

  • Mitosis is the division of the nucleus, producing two daughter nuclei.

  • Prophase (Mitosis)

    • Chromosomes condense and become visible as sister chromatids joined at the centromere.
    • The nucleolus disintegrates and the nuclear membrane breaks down.

  • Metaphase (Mitosis)

    • Chromosomes align at the metaphase plate, attaching to microtubules at the kinetochore.

  • Anaphase (Mitosis)

    • Sister chromatids are pulled apart towards opposite poles; this phase is typically the shortest in mitosis.

  • Telophase (Mitosis)

    • Chromatids reach poles and are redefined as chromosomes; the nuclear membrane reforms.

  • Cytokinesis

    • Division of the cell's cytoplasm results in two new cells.

Cell Cycle Phases

  • Interphase

    • Comprises G1, S, and G2 phases where growth and DNA synthesis occur.

  • G1 Phase

    • Cell is at its smallest size and grows, followed by a checkpoint for readiness to progress.

  • S Phase

    • Each of the 46 chromosomes undergoes duplication.

  • G2 Phase

    • Final growth phase with a checkpoint before mitosis.

Cellular Components

  • Centrosome

    • Composed of two centrioles, aiding in cell division by organizing spindle fibers.

  • Spindle

    • A microtubule structure crucial for chromosome separation during division.

  • Chromosomes

    • Linear DNA molecules wrapped around histones; become visible during prophase.

  • Chromatids

    • Result from replication of chromosomes, appearing as two strands.

  • Centromere

    • Region where sister chromatids are joined and where spindle fibers attach.

Cancer and Genetics

  • Cyclins

    • Proteins that regulate the cell cycle's progression.

  • Carcinoma

    • A type of cancerous tumor.

  • Metastasis

    • The process where cancer cells spread beyond their original site.

  • Mutagen

    • An agent that interacts with DNA, potentially causing mutations.

  • Oncogene

    • Genes that may cause cancer following mutations.

  • Kinetochore

    • Structure that links spindle fibers to centromeres during cell division.

  • Independent Assortment

    • Random assortment of chromosomes during meiosis, contributing to genetic diversity.

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Test your knowledge on the stages of meiosis with these flashcards. Each card contains essential definitions and key processes like prophase, metaphase, and anaphase. Great for students studying cell biology and genetics.

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