6.2 Mitosis Flashcards
why is mitosis important
growth, replacement and repair of cells and tissues and producing genetically identical cells
what happens in mitosis
interphase, prophase, metaphase, anaphase, telophase
what happens in prophase
- chromosomes cool and condense
- spindle fibres and centrioles move to opposite poles of the cell
- nucleolus disappears
- nuclear envelope breaks down
whats the region called where two chromatids are joined
a centromere
what happens in metaphase
-chromosomes are attached to spindle fibres at their centromere and are moved into the middle of the cell and are lined on the metaphase plate
what happens in anaphase
- spindle fibres shorten and centromeres divide so one sister chromosome is pulled either pole, the chromatids from a v shape when being dragged through the cytosol by centromeres
what happens in telophase
- chromotids have now reached the poles and are called chromosomes
- the two new sets of chromosomes assemble at each pole and the nuclear envelope reforms around them
-chromosomes uncoil and the nucleous is formed and cleveage furrow begins (cytokenesis)
how does cytokenesis happen in animals
a cleavage furrow forms around the middle of the cell and the cell surface membrane is pulled inwards by the cytoskeleton until its close enough to fuse forming two cells
how does cytokenesis happen in plant cells
- plant cells have cell walls so they cant form a cleavage furrow
- vesicles from the golgi begin the form in the same place where the metaphase plate was
- the vesicles fuse with each other and with the cell surface membrane dividing the cell in two
- new sections of cell wall form along the new sections of cell membrane
what does mitosis produce
two genetically identical daughter cells
how do you calculate the mitotic index (the proportion of cells undergoing mitosis)
number of cells with visible chromosomes / total number of cells (x100 for a percentage)
