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Questions and Answers
During which phase of meiosis does crossing over occur, and what is the significance of this event?
During which phase of meiosis does crossing over occur, and what is the significance of this event?
- Prophase I; it increases genetic variation by exchanging genetic material. (correct)
- Metaphase I; it ensures proper chromosome segregation.
- Telophase II; it restores the diploid number of chromosomes.
- Anaphase I; it prevents nondisjunction of chromosomes.
How does the alignment of homologous chromosome pairs during metaphase I contribute to genetic diversity?
How does the alignment of homologous chromosome pairs during metaphase I contribute to genetic diversity?
- It leads to the separation of sister chromatids.
- It allows sister chromatids to exchange genetic information.
- It ensures that each daughter cell receives the exact same combination of genes.
- It allows for random assortment of maternal and paternal chromosomes in each daughter cell. (correct)
What is the immediate result of meiosis I?
What is the immediate result of meiosis I?
- Two diploid daughter cells, each with the same genetic information.
- Four haploid daughter cells, each with unique genetic information.
- Four diploid daughter cells, each with a unique combination of genes.
- Two haploid daughter cells, each containing one chromosome from each homologous pair. (correct)
Which of the following statements accurately describes the key difference between anaphase I and anaphase II?
Which of the following statements accurately describes the key difference between anaphase I and anaphase II?
What is the ultimate outcome of meiosis, and why is it significant for sexual reproduction?
What is the ultimate outcome of meiosis, and why is it significant for sexual reproduction?
How does meiosis contribute to the process of gamete formation?
How does meiosis contribute to the process of gamete formation?
Which of the following statements correctly differentiates between mitosis and meiosis?
Which of the following statements correctly differentiates between mitosis and meiosis?
If a diploid cell has 20 chromosomes, how many chromosomes will each daughter cell have after meiosis?
If a diploid cell has 20 chromosomes, how many chromosomes will each daughter cell have after meiosis?
Flashcards
Meiosis
Meiosis
A type of cell division that reduces chromosome number by half to produce gametes.
Meiosis I
Meiosis I
The first phase of meiosis, consisting of prophase I, metaphase I, anaphase I, and telophase I.
Prophase I
Prophase I
Chromosomes condense, homologous chromosomes pair up, and crossing over occurs.
Metaphase I
Metaphase I
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Anaphase I
Anaphase I
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Telophase I
Telophase I
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Gametes
Gametes
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Crossing Over
Crossing Over
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Study Notes
Overview of Meiosis
- Meiosis is a specialized type of cell division that reduces the chromosome number by half.
- It produces gametes (sperm and eggs) in sexually reproducing organisms.
- The process consists of two sequential divisions, meiosis I and meiosis II.
Meiosis I
- Prophase I: Chromosomes condense and become visible. Homologous chromosomes pair up in a process called synapsis. Crossing over (genetic recombination) occurs between homologous chromosomes.
- Metaphase I: Homologous chromosome pairs align at the metaphase plate. The orientation of each pair is random, leading to genetic diversity.
- Anaphase I: Homologous chromosomes separate and move to opposite poles of the cell. Sister chromatids remain attached.
- Telophase I and Cytokinesis: Nuclear envelopes may reform. The cytoplasm divides, producing two haploid daughter cells. Each daughter cell contains one chromosome from each homologous pair.
Meiosis II
- Prophase II: Chromosomes condense if they decondensed in telophase I. Spindle fibers form and attach to chromosomes.
- Metaphase II: Chromosomes align at the metaphase plate.
- Anaphase II: Sister chromatids separate and move to opposite poles.
- Telophase II and Cytokinesis: Nuclear envelopes reform around the separated chromosomes. Cytokinesis occurs, resulting in four haploid daughter cells, each with a unique combination of genes.
Significance of Meiosis
- Genetic Variation: Crossing over and the random alignment of homologous chromosomes during metaphase I contribute significantly to genetic diversity.
- Chromosome Reduction: The reduction in chromosome number from diploid to haploid is essential for sexual reproduction.
- Gamete Formation: The outcome of meiosis is the production of gametes (sperm and egg cells), which unite during fertilization to restore the diploid number of chromosomes.
Differences between Mitosis and Meiosis
- Mitosis produces two genetically identical diploid daughter cells. Meiosis produces four genetically different haploid daughter cells.
- Mitosis is involved in growth and repair. Meiosis is involved in sexual reproduction.
Key Terms
- Homologous Chromosomes: Paired chromosomes with similar genes, one inherited from each parent.
- Crossing Over: The exchange of genetic material between homologous chromosomes, increasing genetic diversity.
- Gametes: Sex cells (sperm and egg cells).
- Diploid: A cell containing two sets of chromosomes (2n).
- Haploid: A cell containing one set of chromosomes (n).
- Genetic Recombination: The process of forming new combinations of alleles on chromosomes.
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Description
Explore the stages of meiosis, a crucial cell division process. Understand how meiosis reduces chromosome number and generates genetic diversity through recombination and independent assortment. Learn about the distinct phases of meiosis I and meiosis II.
