stages of mitosis and meiosis Flashcards
1
Q
what happens at prophase
A
- the chromosomes condense and become visible
- nucleoles and nuclear membrane break down
- centrioles move apart to opposite poles of the cell
- microtubules start to form the spindle
2
Q
what happens in metaphase
A
- chromosomes attach to the spindle fibres by the centromeres
- chromosomes line up along the equator of the cell
3
Q
what happens in anaphase
A
- centromeres divide
- spindle fibres shorten
- this pulls siter chromatids, to opposite poles of the cell
4
Q
what happens in telophase
A
- chromatids separate structures, now coded chromosomes
- chromosomes bind into chromatin
- nuclear membrane reforms
- nucleolus forms in each new nucleus
- spindle fibres break down
5
Q
what happens in cytokinesis
A
- cleavage , cytoplasm divides and cell cleaves into 2
- microfilaments pull in cell surface membrane creating a furrow
- membrane pulled in until 2 daughter cells are formed
6
Q
what happens in prophase II
A
nuclear envelope breaks down
- chromatids condense
- spindle fibres form
- centrioles migrate to poles of the cell
7
Q
what happens in metaphase II
A
- individual chromosomes align on the equator (independent assortment of chromatids)
- the spindle attaches at the centromere
8
Q
what happens in anaphase II
A
- centromeres divide
- chromatids are pulled part to opposite poles of the cells by shaking of spindle fibres
- chromatids are known as chromosomes
9
Q
what happens in telophase II
A
- nuclear membrane reforms
- chromosomes condense
- spindle fibres form
- centrioles migrate to poles of the cell
10
Q
how is genetic variation introduced in meiosis II
A
independent assortment of chromatids in metaphase 2
11
Q
what 2 things caused variation in meiosis
A
crossing over and independent assortment
12
Q
what 2 things caused variation in meiosis
A
crossing over and independent assortment
