Cell division Flashcards
the cell cycle is
regulated sequence of events that occur between one cell division and another
lengthof cell cycle is dependant on
enviroment, eg. cell type and organism
chemical signals triggered that cause movement from one phase to another
cyclins
interphase stages
g1
s
g2
g1 phase
signal is recieved telling the cell to divide
g (growth)
cells make the RNA, enzymes and proteins for growth
s phase
(synthesis)
DNA in nucleus replicates
SAME NO OF CHROMOSOMES
but they now have 2 identical sister chromatids
G2 phase
cell continues to grow.
DNA that has been synthesised is checked and errors are repaired
other preperations for cell division made (eg. production of tunelin in microtubules)
events of interphase table
Stage of interphase Main event(s)
G1 Cell grows and receives a signal to divide
S Synthesis of new DNA
G2
Further cell growth
Error checking of newly synthesised DNA
2 daughter cells produced from mitosis are:
diploid
genetically identical
3 main functions
mitosis
growth
repair
asexual reproduction
asexual reproduction
production of a species by a single parent organism
eg. runners and cuttings
stages of mitosis
I P M A T
i peed myself at tesco
intwerphase
prophase
metaphase
anaphase
telophase
most organisms have _____ chromosomes inm the nuclei
many (46 for humans) yet in diagrams it is often simplified to 4
prophase stages
chromosomes condense
two centrosomes move to opposite poles
spindle fibres begin to emerge from centrosomes
nuclear envelope breaks down
metaphase stages
centrosomes reach opposite poles
spindle fibres continue to extend
chromosomes line up at equator of spindle
spindle fibres attatch to chromosomes
each sister chromatid is attatched to a spindle fibre originating from opposite poles
anaphase stages
sister chromatids seperate at centromere
spindle fibres begin to shorten
seperated sister chromatids (NOW CHROMOSOMES) move to opposite poles
telophase
chromosomes arrive at opposite poles and begin to decondense
nuclear envelopes reform around each set of chromosomes
spindle fibres break down
cytokenisis
cytoplasm splits
in animal cells - cleavage furrow between cells
in plat cells - cell plate between cells
identifying the stages
prophase - visible chromosomes, nuclear envelope breaking down
metaphase - chromosomes lined up along middle of cell
anaphase - chromosomes moving away from middle of cell
telophase - chromosomes at opposite poles of cell
cytokenis - cleavage furrow / cell plate
