cell cycle Flashcards
cell cycle
period of time betweeen the birth of a cell and its own divission to produce two new daughter cells
cycling cells
Cells that continue to divide regularly in definite intervals
what do cyclins activate
cyclin dependant kinases- cdks
what happens to cyclins and cdks at the end of the cell cycle
they are dgeraded
cyclins role
regulate cell cycle progression
ubiquitin
takes up used molecules
is a care taker protein
interphase
The interval between the end of mitosis and beginning of next
s phase
period in which new dna is synthesised
what is the s phase promoted by
cyclin a and cdks
longest phase
g1
g1
cell mostly grows
does g1 have a checkpoint
yes
if dna is damaged what happens
enters g0 phase where it is either repaired or carries out apoptosis
when does dna replication occur
s phase
what occurs during s phase
Each chromosome from g1 is replicated with help from enzymes, energy and structural proteins
Chromatid copied and pasted
Join at centromere
Still make up a single chromosome; amount of info doubled
are more chromosomes made
no just more infomration is added
g2 phase
second growth phase
cell duplicates organelles
what happens post g2 phase
must pass g2 checkpoint to enter mitosis
karyokinesis
dna seperated into 2 distinct nuceli
cytokinesis
seperates daughter cells into 2 distinct cells
prophase
nuclear membrane disintegrates and chromosomes condense and become visible
2 centromeres migrate to opposite ends
metaphase
chromosomes migrate to middle of cell on metaphase plate
once in plane each centrosome sends out thread like prokections
spindle fibres
the thread like projections that centrosomes send out to centromeres
anaphase
centrosome starts pulling on spindle fibres to pull chromatids apart
sister chromatids seperate
telophase
nuclear membranes form around chromosome
cytokinesis ; cell membrane pinches until 2 daughters seperate
when does crossing over occur
prohase 1
what is g1 controlled by
cyclin e and cdks
what controls g2 phase
cyclin b and cdks
where does mitosis occur
somatic cells
colchicine
arrests the cell division at metaphase
prevents formation of microtubules of the spindle
non disjunction
Due to abnormal function of spindle apparatus one or more chromosomes fail to migrate properly in anaphase
one daughter cell recieves extra chromosomes and other daughter cell is deficient inthis chromosome
isochromosome
Sometimes, the centromere splits transversely instead of longitudinal division.
This leads to formation of two daughter chromosome of unequal length
when does the nucleolus appear
telophase
when do chromosomes become uncoiled and lose their indiviudal identity
telophase
