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Ch. 10

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Termini in questo insieme (26)

  • What is the sexual life cycle?

    The sexual life cycle includes meiosis, gamete formation, fertilization, and mitosis, cycling between diploid and haploid stages.

  • What are germ cells?

    Germ cells are specialized diploid cells that undergo meiosis to produce haploid gametes.

  • How are gametes produced?

    Gametes are produced by meiosis from germ cells, reducing chromosome number by half.

  • What is the role of mitosis in the sexual life cycle?

    Mitosis produces somatic cells and allows growth and development from the zygote.

  • How is chromosome number restored during fertilization?

    Fertilization fuses two haploid gametes, restoring the diploid chromosome number in the zygote.

  • Difference between haploid and diploid cells?

    Haploid (n) cells have one set of chromosomes; diploid (2n) cells have two sets.

  • What is crossing over and when does it occur?

    Crossing over is the exchange of genetic material between non-sister chromatids during Prophase I of meiosis.

  • Which chromosomes are involved in crossing over?

    Crossing over occurs between homologous chromosomes, specifically between their non-sister chromatids.

  • What is independent assortment?

    Independent assortment is the random orientation of homologous chromosome pairs during Metaphase I, increasing genetic variation.

  • How does independent assortment increase genetic variation?

    It creates new combinations of maternal and paternal chromosomes in gametes.

  • What is random fertilization?

    Random fertilization is the unpredictable fusion of any sperm with any egg, further increasing genetic diversity.

  • Why are siblings genetically different?

    Because of crossing over, independent assortment, and random fertilization, siblings inherit unique genetic combinations.

  • What happens to chromosome number after Meiosis I?

    Chromosome number is halved; cells become haploid but chromosomes still have sister chromatids.

  • What occurs during Anaphase I vs. Anaphase II?

    In Anaphase I, homologous chromosomes separate; in Anaphase II, sister chromatids separate.

  • Why are the four daughter cells from meiosis non-identical?

    Due to crossing over and independent assortment, each gamete has a unique genetic makeup.

  • Main differences between mitosis and meiosis?

    Mitosis produces two identical diploid cells; meiosis produces four genetically diverse haploid cells with two divisions.

  • Why does meiosis have two divisions?

    To separate homologous chromosomes first, then sister chromatids, halving chromosome number.

  • During which stage does independent assortment occur?

    Independent assortment occurs during Metaphase I of meiosis.

  • Why doesn't crossing over happen in mitosis?

    Mitosis does not involve pairing of homologous chromosomes, so crossing over does not occur.

  • What is nondisjunction?

    Nondisjunction is the failure of chromosomes to separate properly during meiosis, leading to abnormal chromosome numbers.

  • At which stages can nondisjunction occur?

    Nondisjunction can occur during Anaphase I or Anaphase II of meiosis.

  • Difference between nondisjunction in Meiosis I vs. Meiosis II?

    Meiosis I nondisjunction affects homologous chromosomes; Meiosis II affects sister chromatids, resulting in different gamete abnormalities.

  • Why does advanced maternal age increase nondisjunction risk?

    Older eggs have prolonged arrest in meiosis, increasing errors in chromosome separation.

  • What chromosome number results if an egg with 24 chromosomes is fertilized by a normal sperm?

    The zygote will have 47 chromosomes, causing trisomy.

  • Why is Down Syndrome more common than other trisomies?

    Trisomy 21 is more viable and compatible with life compared to other trisomies.

  • Ethical considerations in prenatal testing for Down Syndrome?

    Includes informed consent, privacy, potential discrimination, and decisions about pregnancy continuation.