Chapter 10 - Meiosis

 

Review of Sexual Reproduction

Meiosis

Prophase I the chromosomes wind up and become more compact; the nuclear envelope breaks down; the homologous chromosomes pair up; the homologous chromosomes may exchange pieces of chromosomes (called crossing over); the spindle begins to form; the chromosome pairs attach to the spindle fibers
Metaphase I the spindle fibers pull on the chromosome pairs until they are lined up at the center of the cell
Anaphase I the spindle fibers continue to pull on the chromosome pairs until the homologous chromosomes  separate from one another and are pulled to the ends of the cells; other spindle fibers are pushing the two ends of the cell away from each other
Telophase I when the chromosomes are at opposite ends of the cell, they start to spread out again; the nuclear envelope re-forms; the spindle fibers disappear; cytokinesis begins
Cytokinesis  
Prophase II the chromosomes wind up and become more compact, the nuclear envelope breaks down; the spindle begins to form; the chromosomes attach to the spindle fibers
Metaphase II the spindle fibers pull on the chromosomes until the chromosomes are lined up at the center of the cell
Anaphase II the spindle fibers continue to pull on the chromosomes until the DNA copies (chromatids) separate from one another and are pulled to the ends of the cells; other spindle fibers are pushing the two ends of the cell away from each other
Telophase II when the chromosomes are at opposite ends of the cell, they start to spread out again; the nuclear envelope re-forms; the spindle fibers disappear; cytokinesis begins
Cytokinesis  

 


© Carol L. Wymer, 2004