Meiosis I: Prophase I

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Questions and Answers

What occurs during prophase I of meiosis I?

The chromosomes move to opposite poles

The centrosomes replicate

The cellular membrane is formed

The nuclear envelope disappears and chromosomal crossover occurs (correct)

What is the result of chromosomal crossover during meiosis I?

Reduced genetic variation

No change in genetic variation

Increased genetic variation (correct)

Increased genetic mutation

What is true about metaphase I of meiosis I?

The chromosomes line up along the up-down axis (correct)

The cellular membrane disappears

The nuclear envelope reforms

The centrosomes move to opposite poles

What happens to the nuclear envelope during meiosis I?

It disappears in prophase I Signup and view all the answers

What is the significance of chromosomal crossover in meiosis I?

It adds more variation in sexual reproduction Signup and view all the answers

What is unique about prophase I in meiosis I compared to mitosis?

Chromosomal crossover occurs Signup and view all the answers

What is the result of having homologous sections of chromosomes crossover in meiosis I?

Different alleles are formed Signup and view all the answers

What occurs to the chromosomes during metaphase I of meiosis I?

They line up along the up-down axis Signup and view all the answers

What happens to the homologous pairs in telophase I of meiosis I?

They are fully split apart and move to opposite ends Signup and view all the answers

What is the main difference between telophase I of meiosis I and telophase of mitosis?

Telophase I of meiosis I has homologous pairs, while telophase of mitosis has sister chromatids Signup and view all the answers

What happens to the microtubules during telophase I of meiosis I?

They dissolve Signup and view all the answers

What is the result of meiosis I?

Two haploid cells with two chromosomes each Signup and view all the answers

What happens to the nuclear membrane during telophase I of meiosis I?

It forms again Signup and view all the answers

What is meiosis II similar to?

Mitosis Signup and view all the answers

What happens to the sister chromatids in meiosis II?

They separate from each other Signup and view all the answers

What is the haploid number in each cell after meiosis I?

Two Signup and view all the answers

What happens to the sister chromatids in anaphase I?

They stay together and get pulled to opposite poles. Signup and view all the answers

What is the purpose of microtubules in meiosis?

To move chromosomes to different parts of the cell. Signup and view all the answers

What happens to the homologous pairs in anaphase I?

They get pulled apart and move to opposite poles. Signup and view all the answers

What is the result of anaphase I in terms of genetic variation?

All resulting gametes have different genetic information. Signup and view all the answers

What is the significance of chromosomal crossover in meiosis?

It increases genetic variation amongst gametes. Signup and view all the answers

What is the role of centrosomes in meiosis?

They move chromosomes to opposite poles using microtubules. Signup and view all the answers

What is the difference between anaphase in mitosis and anaphase I in meiosis?

Homologous pairs get pulled apart in anaphase I, but not in anaphase in mitosis. Signup and view all the answers

What is the result of the process described in the passage?

The formation of four gametes with different genetic information. Signup and view all the answers

What is the significance of meiosis in the context of evolution?

It increases genetic variation amongst gametes, which is important for evolution. Signup and view all the answers

What happens to the centromeres during anaphase I?

They stay attached to the sister chromatids. Signup and view all the answers

Study Notes

Meiosis I

Prophase I:
- Nuclear envelope disappears
- Chromosomes condense into dense form with classic shape
- Chromosomal crossover occurs between homologous pairs, adding variation for sexual reproduction
Metaphase I:
- Chromosomes line up along the cell's axis
- Centromeres attach to microtubules, which push centrosomes away from each other
- Microtubules attach to kinetochores on chromosomes, moving them around the cell
Anaphase I:
- Homologous pairs of chromosomes get pulled apart, but sister chromatids stay together
- This differs from mitosis, where sister chromatids get pulled apart
- The split is random, adding more variation to gametes
Telophase I:
- Homologous pairs are fully split apart and at opposite ends of the cell
- Chromosomes begin to unravel into chromatin state
- Nuclear membrane starts to form again
- Cytokinesis begins, eventually separating into two cells
Meiosis I outcome:
- Two haploid cells with a haploid number of two chromosomes each
- Each chromosome has two sister chromatids, to be split in Meiosis II

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Description

This quiz covers the unique features of prophase I in meiosis I, including the disappearance of the nuclear envelope and chromosome condensation. It compares and contrasts prophase I in meiosis with prophase in mitosis.