Meiosis

How many divisions does meiosis have?

Two

What are the stages of meiosis 1?

• Prophase 1

• Metaphase 1

• Anaphase 1

• Telophase 1

What are the stages of meiosis 2?

• Prophase 2

• Metaphase 2

• Anaphase 2

• Telophase 2

What is the major thing that happens in interphase before meiosis 1?

Cell duplicates

• the cell leaves interphase and moves onto prophase 1 with 92 chromatin

The cell leaves interphase and moves onto Prophase 1 with?

92 Chromatin

What happens in Prophase 1?

• Chromatin condenses into chromatids (with their sister chromatids) and forms an X shape

• Synapsis: Homologous chromosomes pair up

• Homologous chromosomes undergo a process called “crossing over” this is when two chromosomes exhange DNA information

• Nucleus begins to dissolve & disappear

What is crossing over?

When two chromosomes exhange DNA information

What is synapsis?

Homologous chromosomes pair up

• forms a tetrad

What does it mean by homologous chromosome pairs?

• One maternal

• One Paternal

What does crossing over create?

Genetic Diversity

What happens in Metaphase 1?

• Chromosomes line up on the metaphase plate

• Spindle fiber elongate and attach to the centromere of each chromosome

What happens in Anaphase 1?

• Homologous pairs are pulled away from each other, each going to opposite ends of the cell

What happens in Telophase 1?

• Cytokinesis splits the cell into two cells

What is the end result of meiosis 1?

2 genetically different Haploid daughter cells

Meiosis 2 is similar too?

Mitosis

What happens in Prophase 2?

• Nucleus dissolves + spindle fibers elongate

What happens in Metaphase 2?

• Chromosomes line up on metaphase plate

What happens in Anaphase 2?

• Spindles attach to the centromere of each chromosome and pull the chromatids apart

What happens in Telophase 2?

• Cytokinesis will split the 2 cells into 4 total cells

The end of meiosis 2 results in

• 4 identical haploid cells

• Each cell will end up with 23 chromatids and 23 chromosomes

• Each cell is different from one another and different from parent cell

If meiosis is happening in a female, then the four cells produced will be?

Eggs

If meiosis is happening in a male, then the four cells produced will be?

Spem cells

Meiosis produces?

• Gametes

• Sex cells

Mitosis produces?

• Somatic cells

• Germ cells