Biology- Chapter 5: Cell Cycle Regulation and Cancer – Flashcards
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3 Principal checkpoints
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control the cycle in eukaryotes; ensure the previous phase is fully completed before advancing to the next phase 1. G1 2.G2 3. M
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G1 Checkpoint
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-Determines whether the cell should divide and enter S phase -Some cells never pass this point and are said to be in G0
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G2 Checkpoint
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This checkpoint leads to mitosis
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M Checkpoint
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Occurs during metaphase and triggers the exit process of the M phase and entry to the G1 phase
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Cancer
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-growth disorder of cells -begins when normal cells grow uncontrollably and spread to other parts of the body
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Tumour
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Result of growing a cluster of cells
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Benign tumours
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surrounded by a healthy layer of cells (AKA encapsulated) and do not spread to other areas
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Malignant tumours
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-Not encapsulated and are invasive -cells from these tumours leave and spread to different areas of the body to form new tumours (called metastases)
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Cancer causes
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Gene disorder in somatic tissue in which damaged genes fail to properly control the cell cycle
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Mutations
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cause damage to genes -may result from chemical or environmental exposure such as UV rays
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Proto-oncogenes
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-genes encode proteins that stimulate cell division -mutations to these genes can cause cells to divide excessively (when mutated - genes become oncogenes
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Tumour-suppressor genes
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-genes normally turn off cell division in healthy cells -when mutated - genes allow uncontrolled cell division
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p53 gene
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-affects the G1 checkpoint; allows damaged cells to divide unchecked
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Malignant tumour formation process
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-up-regulated oncogenes (mutated proto-oncogenes) or down-regulated tumour-suppressor genes both cause increases cell division and tumour development -cancer cells do not undergo cell death, they become immortalized -cells spread to other regions of the body (metastasis) -cells cause growth of new blood vessels so more nutrients can be accessed by cancer cells (angiogenesis)
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Cancer could develop from these mutated genes
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-genes involved in the regulation of the cell cycle (proto-oncogenes + tumour-suppressor genes) -DNA repair enzymes -genes that; increase angiogenesis, prevent apoptosis, regulate the immune response
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Anti-cancer foods
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Contain important phytochemical that either regulate our immune system response, decrease angiogenesis, or they are antioxidants that prevent free radical molecules from damaging our DNA
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immortalized
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cells that do not undergo death
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Metastasis
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Cancer cells spread to other regions of the body
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Angiogenesis
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Cause the growth of new blood vessels so more nutrients can be accessed by the cancer cells
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Most common carcinogens
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-radiation -asbestos -dioxins -tobacco smoke -benzene -aflatoxin -formaldehyde -viruses -charred meat -acrylamide -parabens -pressure treated wood -excessive UV light -aluminum -chronic inflammation
