Meiosis Flashcards

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Questions and Answers

What is a tetrad?

A type of cell division

A paired set of homologous chromosomes (correct)

A stage in mitosis

An unfertilized egg

What occurs during synapsis?

Replication of DNA

Formation of gametes

Separation of sister chromatids

Pairing of homologous chromosomes (correct)

What is crossing over?

The process in which homologous chromosomes exchange portions of their chromatids during meiosis.

What is meiosis?

Cell division that produces reproductive cells (sperm and egg) in sexually reproducing organisms. Signup and view all the answers

What is mitosis?

A nuclear division resulting in two somatic cells having the same genetic complement as the original cell. Signup and view all the answers

What happens during interphase I?

The cell prepares for division by replicating the DNA. Signup and view all the answers

What occurs in prophase I?

Chromosomes condense, homologous chromosomes pair, nuclear membrane breaks apart, and crossing over occurs. Signup and view all the answers

What happens in metaphase I?

The paired homologous chromosomes align at the center of the cell. Signup and view all the answers

What occurs during anaphase I?

The replicated homologous chromosomes are separated and pulled to opposite sides of the cell. Signup and view all the answers

What is telophase I?

The stage where the cell is considered haploid and the number of chromosomes is reduced by half. Signup and view all the answers

What are homologous chromosomes?

A pair of chromosomes that are the same size, appearance, and have the same genes. Signup and view all the answers

What are chiasmata?

Points where chromatids cross over. Signup and view all the answers

What is independent assortment?

The random distribution of the pairs of genes on different chromosomes to the gametes. Signup and view all the answers

What are chromosomes?

Structures in a cell that contain genetic information. Signup and view all the answers

What is a centromere?

Area where the chromatids of a chromosome are attached. Signup and view all the answers

What is meiosis II?

The second phase of meiosis consisting of chromatids separating and the splitting of two diploid cells. Signup and view all the answers

What happens during prophase II?

It is identical to mitotic prophase, but the number of chromosomes was reduced by half during meiosis I. Signup and view all the answers

What occurs in metaphase II?

Chromosomes line up at the equator of the cell. Signup and view all the answers

What happens during anaphase II?

The sister chromatids are separated at their centromeres and pulled to opposite sides of the cell. Signup and view all the answers

What is telophase II?

It is identical to mitotic telophase, with the number of chromosomes reduced by half. Signup and view all the answers

What occurs during cytokinesis in meiosis?

Cytoplasm completely splits resulting in 4 new cells, each with half the number of chromosomes. Signup and view all the answers

What is a diploid cell?

A cell that contains both sets of homologous chromosomes. Signup and view all the answers

What is a haploid cell?

An organism or cell having only one complete set of chromosomes. Signup and view all the answers

What is a sex cell?

An egg or sperm cell (gamete). Signup and view all the answers

What is a body cell?

A somatic cell. Signup and view all the answers

What are female chromosomes?

XX chromosomes. Signup and view all the answers

What are male chromosomes?

XY chromosomes. Signup and view all the answers

What are sex chromosomes?

Chromosomes that determine the sex of an individual. Signup and view all the answers

What are autosomes?

Any chromosome that is not a sex chromosome. Signup and view all the answers

Study Notes

Meiosis Concepts

Tetrad: Comprised of paired homologous chromosomes, each consisting of two sister chromatids, forming during prophase I of meiosis.
Synapsis: The pairing process of homologous chromosomes in diploid cells during prophase I, allowing for crossing over.
Crossing Over: A critical process where homologous chromosomes exchange sections of chromatids, promoting genetic diversity.

Stages of Meiosis

Meiosis: A specialized form of cell division that generates reproductive cells (sperm and egg) in sexually reproducing organisms.
Mitosis: A nuclear division resulting in two somatic cells that retain the same genetic material as the original cell.
Interphase I: The preparatory phase where the cell duplicates its DNA before meiosis begins.

Meiosis I Phases

Prophase I: The longest stage (90% of meiosis I duration) featuring the breakdown of the nuclear membrane, chromosome condensation, and formation of homologous pairs. Crossing over occurs here.
Metaphase I: Tetrads align at the cell's equatorial plane, known as the metaphase plate.
Anaphase I: Homologous chromosomes are separated and pulled to opposite poles of the cell, resulting in the splitting of tetrads.
Telophase I: Similar to mitotic telophase but with half the chromosome amount, resulting in haploid cells where sister chromatids remain connected.

Genetic Diversity Mechanisms

Homologous Chromosomes: Identical in size, shape, and gene content; these can undergo synapsis and crossing over.
Chiasmata: Points of crossover where chromatids exchange genetic material.
Independent Assortment: The random distribution of gene pairs on different chromosomes to gametes, enhancing genetic variation.

Chromosome Structure

Chromosomes: Structures carrying genetic material, essential for hereditary information.
Centromere: The region where sister chromatids are joined together.

Meiosis II Overview

Meiosis II: Focuses on separating chromatids from each other, effectively splitting two diploid cells into four haploid cells.
Prophase II: Similar to mitotic prophase, occurring after the reduction of chromosome number in meiosis I.
Metaphase II: Chromosomes align at the cell equator, akin to mitotic metaphase.
Anaphase II: Sister chromatids separate at their centromeres and are drawn to opposite cell poles, similar to mitotic anaphase.
Telophase II: Final stage where cells transition back to a non-dividing state, akin to mitotic telophase, but with a reduced chromosome number.

Cytokinesis and Chromosome Types

Cytokinesis in Meiosis: Cytoplasm divides, resulting in four new cells, each with half the chromosomal content.
Diploid Cells: Cells containing two sets of homologous chromosomes (2n), typically body or somatic cells.
Haploid Cells: Cells with a single set of chromosomes (n), such as gametes.

Sex and Chromosome Types

Sex Cells (Gametes): Eggs or sperm produced during meiosis.
Body Cells: Also known as somatic cells, containing diploid chromosomes.
Female Chromosomes: Represented as XX, indicating the genetic constitution of females.
Male Chromosomes: Represented as XY, indicating the genetic constitution of males.
Sex Chromosomes: Chromosomes that dictate the sex of an individual.
Autosomes: Non-sex chromosomes that contribute to inheritance other than sex determination.

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Description

Test your knowledge of meiosis with these flashcards. Each card highlights key terms such as tetrad, synapsis, and crossing over, essential for understanding this vital biological process. Perfect for students studying genetics or preparing for exams.