Chapter 10 Mutations and Cancer – Flashcards
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Cancer
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disease of uncontrolled cell division
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BRCA1 and BRCA2 genes
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-located on chromosome 17 and 13 -mutation of these genes increase the rick of breast cancer
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Mutation
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-change in the nucleotide sequence of DNA -affects structure and function of proteins
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Cancer can result if...
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cancer can result if mutation affects normal functioning of cell cycle
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Allele
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alternative form of a gene
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what brings about new alleles?
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-mutations can give rise to alleles -Nucleotides are substituted within a gene
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What causes mutations?
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-Mistakes during DNA replication -DNA polymerase sometimes adds wrong nucleotide;too many or too few bases in a specific location -occurs 1/10,000 to 1/100,000 times
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Mistakes in DNA replication can be repaired
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cells have a proofreading system, however not all cells are always fixed
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What happens to a cell that is irreparable?
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-cells that cannot be repaired self-destruct
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What happens to a mutation that is not repaired?
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a new allele is formed
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Germ-line mutation
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-occurs in gametes and is passed on to offspring -found in every cell of the body -it is heritable, meaning it can be passed on from parents to offspring
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Somatic mutation
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occurs in a body (nongamete) cell and is not passed on to offspring -passed on only to daughter cells of mutated cell -sporadic mutation, meaning they cannot be inherited
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What can homogeneous genetic backgrounds lead to?
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Increased likelihood of passing certain mutations to offspring
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What happens if a mutation alters the amino acid sequence of the corresponding protein?
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-the shape of the protein is change, changing its function
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Hereditary cancer
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-often requires additional nonhereditary mutations to accumulate -Single mutations is not sufficient
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Sporadic cancer
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-requires multiple somatic mutations to accumulate
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Multihit
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-Hit = mutation so, multihit model is a multi mutation model
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Mutations (hits)
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Arise from... -errors in DNA replication -environmental insults ex: chemicals, ultraviolet light, radiations (all factors that damage DNA
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Mutagens
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any chemical or physical agent that can cause DNA mutation
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Carcinogens
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any chemical agent that causes cancer by causing DNA mutations
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What two categories of genes do cancer-causing mutations occur in
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-proto-oncogenes -tumor suppressor genes
