Mitosis As Flashcards
define mitosis
making two identical daughter cells
what is mitosis for
growth, differentiation and repair
what are the phases of mitosis
interphase prophase metaphase anaphase telophase
what are the 3 different parts of interphase
G1 phase
synthesis phase (S)
G2 phase
what happens during G1 phase
organelles synthesised, cell grows
what happens during synthesis phase
DNA replicates
amount of DNA doubles at this point
chromosome number stays the same
what happens during G2 phase
organelles grow
energy stores increase
what does it mean if a cell is only in interphase for a short amount of time
it replicates quickly
what happens during prophase
chromosomes condense and become visible
chromosomes appear as chromatids joined by the centromere
nuclear disintegrates
nucleolus disappears
what happens during metaphase
spindle formed / chromosome / centromere / chromatids attaches to spindle by their centromeres
chromosomes line up at the centre of the equator of the cell
what happens during anaphase
centromere splits
sister chromotids separate
to opposite poles of the cell
what happens during telophase
nuclear envelope reforms
spindle disintegrates
chromosome uncoils / becomes thinner
how do prokaryotes divide
binary fission
process of binary fission
circular DNA replicates and both copies attach to the cell membrane
plasmids replicate
cell membrane grows between two DNA molecules
the cell membrane pinches inward between two DNA molecules, dividing the cytoplasm
a new cell wall forms between the two DNA molecules
why do viruses do viral replication
they are non-living so cannot undergo cell division
process of viral replication
attaches to the host cell with attachment proteins on the surface
inject nucleic acid into the host cell
the nucleic acid is combined with the host cell’s DNA
starts producing viral components
these are assembled into new proteins
define cancer
uncontrolled cell division
what causes cancer
genes that regulate mitosis become damaged
how to treat cancers
drugs which slow/stop cell division by stopping DNA replication or spindles from being made
what is the role of spindles in mitosis
to pull chromatids apart
for the centromere to attach to
why are roots tips examined under microscopes
this is where mitosis can be shown to be happening
why do you press down on root tip
so it spreads out to be thin enough for light to pass through
why do you examine lots of cells to find the mitotic index
ensure a representative sample
why do you do repeated countings when finding a mitotic index
to ensure the figures are correct
