Chapter 10 - Steps of Meiosis I

Question 1

Prophase I

Answer 1

• chromosomes condense progressively
• homologous chromosomes pair up, aligned gene by gene
• crossing over occurs
• each homologous pair has 1. or more chiasmata
• chiasmata exist where crossing over has occurred

Question 2

Metaphase I

Answer 2

• homologous pairs line up at metaphase plate with one chromosome facing each pole
• microtubules from one pole are attached to kinetochore of one chromosome to each tetrad
• microtubules from other pole are attached to kinetochore of other chromosome

Question 3

Anaphase I

Answer 3

• pairs of homologous chromosomes separate
• one chromosome moves towards each pole, guided by spindle apparatus
• sister chromatids remain attached at centromere and move as one unit towards the pole

Question 4

Telophase I and Cytokinesis

Answer 4

• each half of cell has haploid set of chromosomes
• each chromosome still consists of two sister chromatids
• cytokinesis usually occurs simultaneously, forming two haploid daughter cells (animals -> cleavage furrow forms, plant cells -> cell plate forms)