Regulation of cell cycle Flashcards
(20 cards)
What stimulates cell division in multicellular animals?
Growth factors.
Name two examples of growth factors.
Platelet-derived growth factor (PDGF) and Epidermal growth factor (EGF).
Where is PDGF produced and what does it stimulate?
Produced by blood platelets; stimulates proliferation of connective tissue and smooth muscle cells.
What is the source of EGF?
Blood serum and widely distributed in tissues.
How do growth factors trigger cell division?
By binding to receptor proteins and initiating a signal transduction cascade.
What happens to growth factor signalling in cancer cells?
It is circumvented, causing constant signals to divide even without growth factors.
Name the four stages of the cell cycle.
G1 phase, S phase, G2 phase, M phase.
What is interphase?
The combination of G1, S, and G2 phases.
What happens during the G1 phase?
Cell grows and prepares for DNA replication.
What is the G0 phase?
A resting offshoot of G1 where cells may stay for weeks, months, or years.
What occurs during the S phase?
DNA synthesis and doubling of the DNA content.
What happens during the G2 phase?
Preparation for cell division.
What occurs during the M phase?
Division of nucleus (mitosis) and cytoplasm (cytokinesis).
What controls passage through the restriction point?
Cyclin-dependent kinases (Cdks) bound to cyclins.
Are Cdks active alone?
No, they require binding to cyclins.
What are G1 cyclins and G1 Cdks responsible for?
Regulating progression from G1 to S phase.
What are mitotic cyclins and mitotic Cdks responsible for?
Regulating progression from G2 into M phase.
When does mitotic cyclin concentration build up?
Throughout interphase (G1, S, G2).
What triggers the exit from mitosis?
Degradation of mitotic cyclin by the anaphase-promoting complex (APC).
What event allows cells to pass the restriction point into S phase?
Activation of G1 Cdk-cyclin complexes after growth factor signalling.
