Stages of Meiosis Flashcards
Meiosis I
Separation of homologous chromosomes
Prophase I
- Centrosome movement
- Spindle formation
- Nuclear envelope breakdown
- Chromosomes condense
- Crossing Over
- Microtubules attach to kinetochores of a homolog
- Homologs move to metaphase plate
Summary of Prophase I
Duplicated homologs pair and exchange segments (cross over)
Crossing Over
Exchange of genetic information by homologs
Chiasmata
Region where crossovers have occurred
Metaphase I
- Pairs of homologs now arranged at metaphase plate
- Both chromatids of one homolog are attached to kinetochore microtubules of one pole (same for opposite)
Summary of Metaphase I
Chromosomes line up by homologous pairs
Anaphase I
- Homologs separate (breakdown of cohesion proteins)
- Homologs move to opposite poles
- Chromosomes move as a unit toward same pole
Summary of Anaphase I
Each pair of homologous chromosome separates
Telophase I and Cytokinesis
Two haploid cells form; each chromosome consists of 2 sister chromatids; cleavage furrow
In between Meiosis I and Meiosis II?
No chromosome duplication
Meiosis II
Separation of sister chromatids to make 4 haploid daughter cells with unduplicated chromosomes
Prophase II
- Spindle apparatus forms
- Late- Chromosomes move toward metaphase II plate
Metaphase II
- Chromosomes at metaphase plate
- Two sister chromatids not genetically identical
- Kinetochores attached to microtubules from opposite poles
Anaphase II
- Breakdown of cohesion proteins
- Chromatids separate
- Chromatids move to opposite poles as individual chromosomes
