1.5 Protein Control of Cell Division Flashcards
(43 cards)
what does the cytoskeleton do
gives mechanical support and shape to cells
what does the cytoskeleton consist of
different protein structures including microtubules, which are found in all eukaryotic cells
what are microtubules
hollow cylinders composed of the protein tubulin
where are the microtubules found
they radiate from the microtubule organising centre (MTOC) or centrosome
what do microtubules do
control the movement of membrane-bound organelles and chromosomes
what does cell division require
remodelling of the cytoskeleton
what does formation and breakdown of microtubules involve
polymerisation and depolymerisation of tubulin
what do microtubiles form
the spindle fibres that are active during cell division
what does the cell cycle consist of
interphase and mitotic (M) phase
what does the interphase involve
growth and DNA synthesis including:
G1, a growth phase,
S phase, during which the DNA is replicated,
and G2, a further growth phase
what does the mitotic phase involve
mitosis and cytokinesis
what happens in mitosis
the chromosomal material is separated by the spindle microtubules
this is followed by cytokinesis
what happens in cytokinesis
the cytoplasm is separated into two daughter cells
what does mitosis consist of
prophase
metaphase
anaphase
telophase
what is prophase
DNA condenses into chromosomes each consisting of two sister chromatids.
nuclear membrane breaks down.
spindle microtubules extend from the MTOC by polymerisation and attach to chromosomes via their kinetochores in the centromere region
(think pro means before)
what is metaphase
chromosomes are alligned at the metaphase plate (equator of the spindle)
(think middle)
what is anaphase
as spindle microtubules shorten by depolymerisation, sister chromatids are seperated, and the chromosomes are pulled to opposite poles
(think away)
what is telophase
the chromosomes decondense and nuclear membranes are formed around them
(think two)
what is progression in the cell cycle controlled by
checkpoints
what are checkpoints
mechanisms within the cell that assess the condition of the cell during the cell cycle and halt progression to the next phase until certain requirements are met
what is involved in regulating the cell cycle
cyclin proteins that accumulare during cell growth
what do cyclins combine with
they combine with and activate cyclin-dependent kinases (CDKs)
active cyclin-CDK complexes phosphorylate
proteins that regulate progression through the cycle
if sufficient phosphorylation is reached, progression occurs
what happens at the G1 checkpoint
retinalblastoma proteins (Rb) acts as a tumour suppressor by inhibiting the transcription of genes that code for proteins needed for DNA replication
