mitosis Flashcards
3 stages of cell cycle ?
replication
mitosis
cytokinesis
4 stages of cell cycle and what they mean?
g1 phase: decides when to divide
s ; duplicate genome
g2; check no errors
m ; cytokinesis
explain what happens during g1
to decide to divide or not
external factors such as growth or cell density
internal signals such as dna duplicated or absence of dna damage
explain what happens during s phase
duplicating cells genome
chromosomes - single linear dna packages
replicated to two sister chromatids
explain what happens during g2 checkpoint
allows time to ensure all dna replicated
time to repair damaged dna
what happens during m phase?
mitosis
three problems with mitosis?
.1 physically moving chromosomes
- cells need make sure all info passed on
- nuclear envelopes open vs closed mitosis
how are chromosomes transported?
mitotic spindles made from microtubules, filaments made of alpha and beta tubulin composed into dimers
what is the centrosome?
microtubule organising centre, consist of 2 centrioles
what are the two different types of microtubules within spindles?
interpolar MTSand aster MTS= shaping the spindle kinetichore mTS= transport chromosomes
what do kinetichore proteins do?
mediate mT to DNA attatchment
what is cytokinesis?
separation of cytoplasm, cleavage furrow formation
what is a midbody?
small remnant stays behind where spindle is squeezed by ring
three ways that cell cycle is regulated?
cyclically operating molecule to trigger events
cyclin depedant kinase drive cell cycle
different cyclins are expressed at different stages of cycle
cyclin dependant kinase stages?
kinase catalyse transfer of phophate onto target, used as a s swithc, cdks are inactive on own
