KA5: protein control of cell division: control of the cell cycle Flashcards
what is progression through the cell cycle controlled by?
checkpoints
describe the role of checkpoints
mechanisms within the cell that:
-assess the condition of the cell during the cell cycle
-halt progression to the next phase until certain requirements are met
what are the cyclin proteins that accumulate during cell growth involved in?
regulating the cell cycle
describe the role of cyclin proteins in regulating the cell cycle
-combine with and activate cyclindependent kinases (CDKs).
-active cyclinCDK complexes phosphorylate proteins that regulate progression through the cycle.
-if sufficient phosphorylation is reached, progression occurs.
describe the role of retinoblastoma protein (Rb) at the G1 checkpoint
acts as a tumour suppressor by inhibiting the transcription of genes that code for proteins needed for DNA replication
what does phosphorylation by G1 cyclin-CDK do to the Rb protein ?
what does this allow?
inhibits it
transcription of the genes that code for proteins needed for DNA replication. Cells progress from G1 to S phase
what occurs at the G2 checkpoint?
-success of DNA replication
-any damage to DNA
what does DNA damage trigger?
the activation of several proteins including p53 that can
-stimulate DNA repair
-arrest the cell cycle
-cause cell death
describe the role of the metaphase checkpoint
controls progression from metaphase to anaphase
describe what happens at the metaphase checkpoint
progression is halted until the chromosomes are aligned correctly on the metaphase plate and attached to the spindle microtubules.
what can uncontrolled reduction in the rate of the cell cycle result in?
degenerative disease
what can uncontrolled increase in the rate of the cell cycle result in?
tumour formation
What is the proto-oncogene
a normal gene, usually involved in the control of cell growth or division, which can mutate to form a tumour promoting oncogene
draw the cell cycle checkpoints diagram
