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26 Cards in this Set
- Front
- Back
Prophase
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-lamins A,B,C are phosophorylated ="nuclear dissolution"
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G0
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cell is not actively engaged in division
-"quiescent period" -cell can be differentiated |
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G1
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- 9 hours long, most variable in time
- need growth factors - early and late response genes - sensitive to amino acid deprivation (protein synthesis) -cell synchrony |
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What experiment did Arthur Pardee do?
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- took 3T3 mouse cells
-found that you need growth factors (PDGF, EGF, insulin) to move on through cell cycle |
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What happens when you add protein synthesis inhibitors to the G1 phase?
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No late response genes
-need degradation of early response genes -late and early response genes are linked to each other |
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What is cell synchrony? What happens?
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Cell are synchronized according to the phase and the things available/present at the cell.
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Amino acid deprivation will stop...
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the G1 phase
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Reversible DNA synthesis inhibitors block...
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at the S phase
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Protein synthesis inhibitors stops...
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the G1 phase
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Microtubule inhibitors blocks...
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the M phase
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Heat stops...
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the M phase
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What are restriction points? Where is it?
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points beyond which cells are COMMITTED to divide. At G1 (unique only to G1)
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What is required for G1 passage? How do you know?
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cyclin D; use of BRDU (like 3H-thymidine, but NOT radioactive)
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What are checkpoints?
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-checks the fidelity of the phase's activity
-occurs at every juncture |
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S phase
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-DNA doubles
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Explain the fiber autoradiography experiment. What did it discover.
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take cell in S phase --+ 3H-thymidine--> take out DNA --> autoradiography --> see pattern that tells us DNA synthesis is occuring in BOTH directions and there are multiple origins ("replicons")
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M phase
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Prophase, Metaphase, Anaphase, telophase (PMAT)
- shortest in time (30 mins) - need MPF and cyclin B |
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What triggers or regulates mitosis? How do you know?
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- maturation promoting factor (meiotic cells) = MPF = mitosis phase factor (somatic cells) (induces a mitotic spindle)
- cyclin B -protein synthesis - X. laevis |
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What is the cell free cell cycling experiment and what did it show?
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Take X. laveus, frog sperm nuclei, cytoplasm and ATP into test tube --time--> mitosis occurs
- now cell free system can manipulate the system -protein synthesis and mRNA cyclin B is required for M phase |
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What is the relationship between cyclin B and MPF?
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MPF consists of cyclin B and CDK (cyclin dependent kinase)
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What does ubiquitin need and why?
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Cyclin B --> triggers hydrolysis of cyclin B --> MPF is no longer active
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What is yeast important in? Types of yeast?
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cell cycle regulation
-S. cervisae - budding yeast - S. pombe - fission yeast |
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What is p53?
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-tumor suppressor gene
-triggered by ATMR (detects damarage --> phosphorylated p53 --> stabilizes p53) -triggers p21 --> blocks cyclins -"guardian of the genome" - causes cells to die (apoptosis) if a lot of errors with cell or fixes the problem |
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What happens when p53 is defective?
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- seen in about 50% cencers
-can't commit radiated cells to apoptosis |
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What was Ruth Sager's experiment?
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took normal and cancer cells --> hybridoma --> cell division (genes are lost, p53 is lost) --> cancer cell
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Who were the first two people to look at the cell cycle?
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1953 - Howard and Pelc
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