Meiosis Ch. 6.2

Diploid (2n): two identical copies of every chromosome Diploid (2n): two identical copies of every chromosome. (ALL somatic cells) Human diploid # = 46 Haploid (n): one copy of every chromosome. (ONLY sex cells) Human haploid # = 23 Diploid Haploid

Tetrad Mom Dad Prophase 1 – Meiosis 1 synapsis Synapsis happens. Crossing-over happens. Crossing-over results in genetic recombination, which creates more diversity among offspring. synapsis Mom Dad

Homologous pair undergoing crossing over Synapsis: Homologous chromosomes pair up with each other & form a tetrad. Crossing over: parts of homologous pairs break off and re-form on the adjacent chromosome. Leads to variation! Homologous pair undergoing crossing over * Notice: chromosomes are aligned so the genes on one match corresponding genes on the other.

Metaphase 1 – homologous pairs line up in the middle of the cell Spindle fibers attach to one of each chromosome pairs.

Anaphase 1 – homologous pairs split apart from each other Independent assortment happens

Independent assortment: Chromosomes separate from each other randomly.

Telophase 1 – We end up with 2 haploid cells Telophase 1 – We end up with 2 haploid cells. These cells enter Meiosis 2

Prophase I

Metaphase I

Anaphase I

Telophase I

Prophase II

Metaphase II

Anaphase II

Telophase II