Meiosis II Overview

Interphase II

• Sometimes there is a rest period called interphase II between meiosis I and meiosis II.
• The existence of interphase II depends on the type of cell and species.

Phases of Meiosis II

Prophase II

• Occurs in two cells formed after meiosis I.
• Nuclear Envelope: Dissolves.
• Chromosomes: Condense again, showing crossover sections from prophase I.
• Centrosomes: Duplicate and begin migrating to opposite ends of the cell.
• Similar to prophase in mitosis.

Metaphase II

• Centrosomes have migrated to the cell poles.
• Nuclear Membrane: Has disappeared.
• Chromosomes: Line up along the cell equator.
• Microtubules: Attach to chromosomes at kinetochores and aid in pulling apart.

Anaphase II

• Analogous to anaphase in mitosis.
• Sister Chromatids: Split to become daughter chromosomes, moving to opposite cell ends.
• Microtubules: Involved in movement, elongating and pulling chromosomes.
• Chromosomes move due to motor proteins along the microtubules.

Telophase II

• Transition from two cells to four cells.
• Chromosomes: Start to unravel into chromatin.
• Nuclear Envelope: Begins reforming around the chromatin.
• Microtubules: Dissolve.
• Cytokinesis: Final division of the cell, resulting in four haploid cells.

Outcome of Meiosis II

• Results in four haploid gametes.
• Each gamete has two chromosomes, not homologous, coding for different genes.
• Meiosis II preserves chromosome number, unlike meiosis I, similar to mitosis.
• Ends with cells ready for fertilization.

Importance for Reproduction

• Resulting gametes are crucial for sexual reproduction.
• Gametes can fuse during fertilization to create a diploid cell with a full set of homologous chromosomes.