Meiosis Phases Flashcards

Study Notes

Meiosis Overview

Meiosis produces four haploid gametes from one diploid cell, essential for sexual reproduction.

Interphase (Stage 1)

DNA exists in chromatin form and undergoes replication, preparing for the meiotic process.

Prophase I (Stage 2)

DNA coils into visible chromosomes; sister chromatids are linked by a centromere.
Nuclear membrane begins to dissolve; centrosomes move to poles and spindle fibers form.
Crossing over occurs, allowing genetic material exchange between homologous chromosomes.

Crossing Over

A process where homologous chromosomes pair up and exchange genetic information, enhancing genetic diversity.

Homologous Chromosomes

Chromosomes from each parent that match in size and shape, contributing to genetic variation.

Metaphase I (Stage 3)

Fully formed spindle fibers attach to centromeres of homologous chromosomes.
Chromosomes align at the cell's equatorial plane alongside their homologous partners.

Anaphase I (Stage 4)

Spindle fibers pull homologous chromosomes toward opposite poles, leading to chromosome separation.

Telophase I (Stage 5)

Chromosomes reach poles and nuclear membranes reform around each set, initiating de-coiling into chromatin.
Cytokinesis divides the cell, resulting in two diploid cells, which will undergo further division.

Cytokinesis

Division of the cytoplasm occurs during Telophase I and II, concluding each meiotic division phase.

Prophase II (Stage 6)

No interphase occurs between Meiosis I and II; chromosomes reorganize and nuclear membranes dissolve.
Sister chromatids are again connected by centromeres as spindles reform.

Metaphase II (Stage 7)

Spindle fibers attach to centromeres of the chromosomes, which realign in a single row along the spindle's equator.

Anaphase II (Stage 8)

Spindle fibers pull sister chromatids apart, moving each to opposite poles of the cell.

Telophase II (Stage 9)

Nuclear membranes form around each chromosome set; cleavage furrows develop.
Resulting in four haploid cells: in males, four functional sperm; in females, one viable egg and three polar bodies, which are generally non-functional.

Chromatin

Thread-like structures containing genetic information, visible only during Interphase, crucial for genetic material organization and replication.

Description

Explore the key phases of meiosis with these flashcards. Each card presents essential terms and definitions related to the process of meiosis, including interphase and prophase I. Perfect for high school biology students aiming to enhance their understanding of gamete formation.