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15 Cards in this Set
- Front
- Back
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List and describe the checkpoints in the cell-cycle |
G1(1): restriction checkpoint: check for cell size and for favorable conditions G1(2): check for DNA damage before entering S phase G2: check for damaged or unduplicated DNA and unduplicated centrosomes M: check chromosomes are attached to the mitotic spindle |
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What cyclin-dependent kinases regulate the cell cycle checkpoints? |
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Describe what happens in the different stages of the cell cycle |
G1: growth and duplication of components (minus chromosomes) S: synthesis (duplication of DNA) G2: growth and preparation for mitosis M-phase: nuclear division Cytokinesis: cytoplasmic division G0: quiescence |
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List the stages of cell cycle by their duration |
G1 (10 hours) S (7.5 hours) G2 (3.5 hours) M (1 hour) |
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Draw a picture of the cell cycle |
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Describe the what happens in interphase, M-phase and quiescence |
Interphase is composed of G1, S-phase and G2. The cell grows in size, synthesises DNA, and duplicates its organelles for division. M-phase it composed of mitosis and cytokenisis. The cell cell condenesse and separates its chromosomes, and is then cleaved. In quiescence, the cell is not actively proliferating - i.e. not in the cell cycle. It may, however, be performing a designated function. |
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What is a kinase? |
An enzyme that adds a phosphate group to its substrate. |
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Describe the difference between oncogens and proto-oncogenes |
- Proto-oncogenes code for proteins that are needed for normal cell proliferation. - oncogenes promote malignant changes in a cell by ignoring normal growth signals - Proto-oncogenes which undergo activating mutations become oncogenes, therefore promoting tumourogenesis |
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In what ways may the product of an oncogene promote neoplasia (4) |
- protein may be hyperactive - proteins may be normal but produced in higher quantities - proteins may be normal but produced at an innappropriate time - protein may be in the wrong cell type |
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Give three examples of genetic abnormalities which could give rise to an abnormally active protein |
- point mutation (Ki-ras gene in colon cancer) - deletion (Chromic Myelogenous Leukaemia) - chromosomal rearrangement (bcr-abl gene) |
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Describe 3 ways in which uncontrolled cellular proliferation may occur |
Activation of a proto-oncogene whose normal role is to stimulate cell proliferation
Loss of both copies of a tumour suppressor gene whose normal function is to act as a brake on cell proliferation Constitutive expression of telomerase, leading to immortalisation of cell |
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Describe the influence of high and low levels of P53 on a cell |
high levels: switches on pro-apoptotic genes low levels: switches on p21 cdki (regulator of G1 and S-phase checkpoints) |
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How do the requirements of tumour cells change as they grow? How do they combat this? |
- become hypoxic as they become too large to attain oxygen by diffusion - stimulates production of VEGF for angiogenesis |
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What is the most common form of cancer? |
carcinoma (80%) |
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What causes most cancers to break through the basement membrane? Name 2 components that promote this |
a decrease or dysfunction in the e-cadherins holding epithelial cells together Matrix Metalloproteinases and Urokinase Plasminogen Activator |
