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29 Cards in this Set
- Front
- Back
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Mutation |
Change in DNA sequence |
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Point mutation |
nts Same number of ntsOne nt changed to a different one |
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Frameshift mutation |
Changes number of NTS Adding or deleting at least onr |
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Types of point mutation |
Silent Missense Nonsense |
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Point: silent |
Change but new NT codes for same amino acid |
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Point:missense |
NT changed and new codon codes for new AA |
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What disease is caused by a missense mutation |
Sickle cell anaemia |
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Nonsense mutation |
One NT changed and codes for stop codon. New protein is shortened and missing some amino wcids |
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Start |
Met Aug |
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Stop |
UAG |
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Types of frameshift mutation |
Insertion Deletion |
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What's a somatic cell |
A body cell thats not reproductive |
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What's a germ line cell |
Reproductive cell that makes sex cells |
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What happens if a gamete has a mutation |
All cells in the embryo will have mutation and all cells in the organism will have one copy of the mutation |
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What will happen if a somatic cell has mutation |
Every time the cell divides. The daughter cells inherit the mutation Results in patch of cells with mutation |
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Will somatic mutations be inherited? |
No because none of the germ line cells have the mutation |
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What causes mutations? |
Spontaneous and induced mutations |
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Spontaneous mutations are caused by mistakes in cellular processes or metabolism. Give examples |
Errors during DNA replication Toxic metabolic products Changes in NNT structure Transposons |
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Errors in DNA Replication |
Proofreading doesn't remove all mismatched bases DNA repair enzymes fail yo remove all mistakes or damage |
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Toxic metabolic products |
Metabolism produces reactive chemicals that change the structure of bases in DNA |
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Natural change |
Tautomer- Bases can form alternate forms/isomers which can cause mispairing in DNA replication |
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Transposons |
Jumping genes 1000s of bases long If inserted into a gene it can cause mutation Type of frameshift mutation (insertion) |
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Induced mutations are |
Caused by environmental agents eg chemicals and physical agents (UV lights and x rays) |
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What will chemicals do |
Change the structure of bases in dna |
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What do physical agents do (UV light) |
Produces thymine dimers |
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What's a thymine dimer |
Two thymines on the same strand of DNA form a covalent bond During DNA replication TD isn't recognised as two thymines but one abnormal base. Causing mismatched bases to be added and this can block DNA replication. |
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Mismatch repair |
Removes mismatched bases that are present after DNA replication is complete |
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Nucleotide excision repair |
Removes abnormal bases and thymine dimers Uvra and uvrb form complex Moves along DNA looking for abnormal bases Complex bind to region surrounding abnormal base Uvra is released Uvrc binds to uvrb and cut out region of DNA surrounding abnormal base Urvd unwinds DNA and removes cut piece of dna DNA polymerase fills gap with DNA DNA ligase connects pieces of DNA together |
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Xeroderma pigmentosa |
Caused by defect in DNA repair enzymes that remove thymine dimers Patients develop precancerous lesions. Cancer, blisters etc when exposed to light |
