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Cell Cycle Regulator Molecules
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Biology
Cells
Cell Cycle
Cell Cycle Regulator Molecules
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1
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When Rb is bound to E2F
production of proteins necessary for the G1 /S transition is blocked.
2
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Retinoblastoma protein (Rb), p53, and p21are
negative regulatory molecules
3
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As a cell is exposed to more stress,
higher levels of p53 and p21 accumulate, making it less likely that the cell will move into the S phase.
4
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In the active, dephosphorylated state, Rb binds to
proteins called transcription factors, most commonly, E2F.
5
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Rb exerts its regulatory influence on
other positive regulator proteins.
6
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If damaged DNA is detected, p53
halts the cell cycle and recruits enzymes to repair the DNA.
7
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Cyclins regulate the cell cycle only when
they are tightly bound to Cdks.
8
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Regulator molecules may act
individually, or they can influence the activity or production of other regulatory proteins.
9
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Transcription factors
________:"turn on "specific genes, allowing the production of proteins encoded by that gene.
10
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As the cell increases in size
Rb is slowly phosphorylated until it becomes inactivated.
11
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If the DNA can't be repaired
p53 can trigger apoptosis, or cell death, to prevent the duplication of damaged chromosomes.
12
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P21
________ enforces the halt in the cycle dictated by p53 by binding to and inhibiting the activity of the Cdk /cyclin complexes.
13
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Retinoblastoma proteins
a group of tumor-suppressor proteins common in many cells
14
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Transcription factors
"turn on" specific genes, allowing the production of proteins encoded by that gene
15
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Regulatory molecules either
promote progress of the cell to the next phase (positive regulation) or halt the cycle (negative regulation)
16
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What two groups of proteins are responsible for the progress of the cell through the various checkpoints?
cyclins and cyclin-dependent kinases (Cdks),
17
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Increases in the concentration of cyclin proteins are triggered by
both external and internal signals.