Protein Control of Cell Division 1.5 Flashcards
what is the purpose of the cytoskeleton?
to give mechanical support and shape to cells
what does the cytoskeleton consist of?
different protein structures:
-microtubules (found in all eukaryotic cells)
what do microtubules control?
the movement of membrane-bound organelle and chromosomes
what is required for division
remodelling of the cytoskeleton
what is involved in the formation and breakdown of microtubules
the polymerisation and depolymerisation of tubulin
what forms the spindle fibres that are active during cell division?
microtubules
what does the cell cycle consist of?
interphase and mitotic (M) phase
what is involved in the mitotic phase?
mitosis and cytokinesis
name the four stages of mitosis
prophase, anaphase, metaphase and telophase
how is the progession of the cell cycle controlled?
by checkpoints
describe what happens at the G1 checkpoint
retinoblastoma protein (Rb) acts as a tumour suppressor by inhibiting the transcription of genes that code for proteins needed for DNA replication
what causes the inhibition of the retinoblastoma protein (Rb)?
phosphorylation by G1 cyclin - CDK
describe what happens at the G2 checkpoint
- success of DNA replication and any damage to DNA is assessed
- DNA damage triggers the activation of several proteins including p53 - stimulates DNA repair, cell arrest, cause cell death
what does the metaphase checkpoint control?
the progression from metaphase to anaphase
what may result in degenerative disease?
an uncontrolled reduction in the rate of the cell cycle
what may result in the formation of a tumour?
an uncontrolled increase in the rate of the cell cycle
what is proto-oncogene?
a normal gene - involved in the control of cell growth/division
- can mutate to form a tumour-promoting oncogene
what triggers apoptosis?
cell death signals that can be external or internal
how do external death signal molecules work?
they bind to a surface receptor protein and trigger a protein cascade within the cytoplasm
how do internal death signal molecules occur?
it cause the activation of p53 tumour suppressor protein which has resulted from DNA damage
true or false?
both types of death signal result in the activation of caspases that cause the destruction of the cell
true
why is apoptosis essential during the development of an organism?
to remove cells no longer required as development processes or during metamorphosis
why may cells initiate apoptosis?
due to the absence of growth factors
what molecules are involved in regulating the cell cycle?
cyclin proteins that accumulate during cell growth
