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14 Cards in this Set
- Front
- Back
cell cycle |
orderly sequence of events by which a cell duplicates its contents and divides in two |
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cyclin dependent kinase |
Cdk catalytic subunit present at same quantity throughout cell cycle |
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cyclin |
regulatory subunit (Cdk inactive in absence of cyclin binding) rises and falls in concentration at specific points in cell cycle directs Cdk to appropriate substrates |
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options for cells that complete mitosis |
1. exit cell cycle and enter G0 (quiesence) 2. continue through G1 phase and enter S phase |
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characteristics of G0 arrest |
cell has same DNA content as G1 phase cell cell hasn't past R point cells not synthesizing proteins for DNA synth. cell is metabolically active cell type specific proteins expressed "doing its job" |
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conditions that result in G0 arrest |
absence of growth factors absence of amino acids (nutritional deprivation) cell-cell contact |
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characteristics of G1 phase |
prep for entry into S phase! assemble preRCs (inactive until S) synthesize rRNA and proteins to support synthetic activity Restriction point- in late G1 phase |
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Restriction point |
regulatory point in late G1 phase after passing R point cell is committed to enter S phase aka "start" or "point of no return" |
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passage through R point regulated by |
binding of soluble growth factors to receptors integrin-mediated adhesion to ECM Rb protein and its phosphorylation state |
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E2F |
regulates transcription of genes encoding proteins required for DNA synthesis action is inhibited by Rb binding |
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S phase |
time when cell carries out complete and accurate replication of cellular genome replication origins are not activated simultaneously |
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S phase to G2 phase transition |
cyclin A/cdk2 binds to and phosphorylates E2F complex to make it NOT bind to promoter turns off transcription of S phase genes |
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G2 phase |
1. prevent re-initiation of DNA synthesis 2. decatenation (disentangling) of replicated DNA by topoisomerase II 3. synthesis, assembly, and modification of proteins that regulate G2-->M transition |
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what triggers the G2-->M transition |
Cyclin B and Cdk (MPF) |