Questions and Answers
What is meant by homologous chromosomes?
Chromosome pairs, one from each parent, that are similar in length, gene position, and centromere location.
What is the difference between sister chromatids and homologous chromosomes?
Sister chromatids are identical, while homologous chromosomes are inherited from different parents and may contain different versions of some genes.
How many cell divisions occur in one meiotic division?
Two cell divisions occur during meiosis.
How many cells result from meiosis?
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During which division is the chromosome number reduced in half?
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What are the names of the stages of meiosis?
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What is synapsis and during which stage does it occur?
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What is crossing over, when does it occur, and what is the result?
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What are the similarities between spermatogenesis and oogenesis?
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What are the differences between spermatogenesis and oogenesis?
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What are homologous chromosomes?
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What occurs during crossing over?
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Study Notes
Homologous Chromosomes
- Homologous chromosomes consist of pairs of chromosomes: one inherited from the mother and one from the father.
- They are similar in length, gene position, and centromere location but may have different alleles.
- Each carries the same genes but not necessarily the same versions (alleles), leading to variation in traits like hair color.
- Sister chromatids are identical copies of a chromosome, while homologous chromosomes come from different parents and may differ in their genetic makeup.
Meiotic Division
- Meiosis consists of two cell divisions: Meiosis I and Meiosis II.
- During Meiosis I, chromosomes recombine, resulting in genetically diverse gametes; Meiosis II produces four haploid cells.
- The chromosome number is halved during Meiosis I, resulting in cells with half the original chromosome count.
Stages of Meiosis
- The stages of meiosis are:
- Prophase I
- Metaphase I
- Anaphase I
- Telophase I
- Prophase II
- Metaphase II
- Anaphase II
- Telophase II
Synapsis
- Synapsis occurs during Prophase I, where homologous chromosomes pair up in a highly specific alignment.
Crossing Over
- Crossing over happens in Prophase I when sister chromatids exchange segments of genetic material.
- This gene swapping introduces genetic diversity and can lead to new phenotypes after fertilization.
Gametogenesis: Spermatogenesis vs. Oogenesis
- Both processes involve meiosis but produce different outcomes.
- Spermatogenesis results in four sperm cells, while oogenesis produces one ovum and three polar bodies.
- Spermatogenesis occurs in the testes and has a shorter growth phase, while oogenesis occurs in the ovaries and has a longer growth phase.
Key Differences in Gametogenesis
- Spermatogenesis forms sperm; oogenesis forms ova.
- Polar bodies are formed during oogenesis but not during spermatogenesis.
- A single germ cell can produce 16 sperm, in contrast to the four ova produced from one germ cell in oogenesis.
Characteristics of Homologous Chromosomes
- Cells contain two of each chromosome type, with one from each parent.
- Paternal and maternal chromosomes may carry different alleles, contributing to genetic variation.
Cross-linking in Crossing Over
- During crossing over, homologous chromosomes become tightly aligned, allowing for the exchange of segments between non-sister chromatids.
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Description
Test your understanding of meiosis with these flashcards. This quiz focuses on homologous chromosomes, their similarities, and differences. Perfect for reviewing key concepts from Chapter 7 of your biology class.
