6.1 (2.1.6) Mitosis

what is mitosis used for

growth, repair of tissues, asexual reproductions in plants and fungi

define chromatid

one of the two identical halves of a chromosome that has been replicated in preparation for cell division

what is the region called in which two chromatids are joined

centromere

describe prophase in animal cells

1) chromatin fibres coil and condense to form chromosomes

2) nuclear membrane begins to breaks down

3) protein microtubules form spindle fibres

4) two centrioles migrate to opposite poles of the cell

5) the spindle fibres attach to specific areas on the centromeres and start to move the chromosomes to the centre of the cell

6) nuclear envelope disappears

describe metaphase

chromatids line up along the metaphase plate

describe anaphase

centromeres divide into two and the spindle fibres contract to pull the sister chromatids to opposite poles of the cell

describe telophase

1) chromatids reach poles and are now called chromosomes

2) the two new sets of chromosomes assemble at each pole

3) nuclear envelope reforms

4) chromosomes uncoil and lengthen and the nucleolus is formed

describe cytokinesis in animal cells

1) cleavage furrow forms around middle of the cell

2) plasma membrane is pulled inwards by the cytoskeleton and fuses around the middle to form two diploid cells

describe cytokinesis in plant cells

1) vesicles from the Golgi body begin to assemble in the same place as the metaphase plate

2) the vesicles fuse with each other and the plasma membrane which divides the cell into two

3) new sections of cell wall form