7b Meiosis Flashcards
Can you compare meiosis to mitosis?
Mitosis:
Purpose: Cell division for growth, repair, and asexual reproduction.
Process: One division, resulting in two identical diploid cells.
Genetic Variation: No genetic variation; daughter cells are clones of the parent cell.
Meiosis:
Purpose: Production of gametes (sperm and ova) for sexual reproduction.
Process: Two divisions, resulting in four non-identical haploid cells.
Genetic Variation: Increases genetic diversity through crossing over and independent assortment.
Can you explain what occurs at each phase of meiosis?
Meiosis I:
Prophase I: Chromosomes condense, homologous chromosomes pair (synapsis), and crossing over occurs.
Metaphase I: Homologous chromosomes align at the metaphase plate.
Anaphase I: Homologous chromosomes separate and move to opposite poles.
Telophase I & Cytokinesis: Two haploid cells form, each with half the number of chromosomes.
Meiosis II:
Prophase II: Chromosomes re-condense in the two haploid cells.
Metaphase II: Chromosomes align at the metaphase plate.
Anaphase II: Sister chromatids separate and move to opposite poles.
Telophase II & Cytokinesis: Four non-identical haploid cells are formed.
What is Meiosis and what is its outcome?
Definition: Meiosis is a type of nuclear division that reduces the chromosome number by half, producing haploid cells.
Outcome: The production of gametes (sperm and ova) in sexually reproducing organisms.
Terms:
Haploid: Cells with one set of chromosomes.
Diploid: Cells with two sets of chromosomes.
Gametes: Reproductive cells (sperm and ovum).
Where does meiosis take place?
Location: Meiosis occurs in the reproductive organs:
In males, it takes place in the testes (spermatogenesis).
In females, it takes place in the ovaries (oogenesis).
Draw and label the stages of Meiosis
Stages:
Meiosis I: Prophase I, Metaphase I, Anaphase I, Telophase I
Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II
What is crossing over and what stage does it occur?
Definition: Crossing over is the exchange of genetic material between homologous chromosomes.
Stage: It occurs during Prophase I of meiosis.
Terms:
Chiasmata: The points where chromosomes cross over.
Synapsis: The pairing of homologous chromosomes.
Tetrad: A group of four chromatids (two homologous chromosomes) during synapsis.
What is independent assortment and what stage does it occur?
Definition: Independent assortment is the random distribution of maternal and paternal chromosomes into gametes.
Stage: It occurs during Metaphase I of meiosis.
Why are crossing over and independent assortment important in Meiosis?
Importance: Both processes increase genetic diversity:
Crossing Over: Creates new combinations of genes on each chromosome.
Independent Assortment: Results in a random mix of maternal and paternal chromosomes in gametes.
What is spermatogenesis and what is the outcome?
Definition: Spermatogenesis is the process of sperm cell development.
Outcome: Four haploid sperm cells from each diploid precursor cell.
What is oogenesis and what is the outcome?
Definition: Oogenesis is the process of egg (ovum) cell development.
Outcome: One mature ovum and three polar bodies (which typically degenerate) from each diploid precursor cell.
