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How do external influences create mutations?
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Mutations can also be caused by exposure to specific chemicals or radiation. These agents cause the DNA to break down. When the cell repairs the DNA, it might not do a perfect job of the repair. So the cell would end up with DNA slightly different than the original DNA and hence, a mutation.
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Define mutation.
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Change in the nucleotide sequence of a genome
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Name the mutation:A type of mutation where an amino acid sequence is not altered, because new codon codes for same amino acid.
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 Silent mutations |
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Name the mutation:This type of mutation specifies a different type of amino acid and can result in a non-functional protein, or may have no adverse effect.
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 Missense mutations |
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Name the mutation:In this type of mutation, substitution changes an amino acid codon into a stop codon. Nearly all mutations result in nonfunctional proteins.
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 Nonsense mutations |
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Name the mutation:Addition or Deletion of a nucleotide. Nucleotide triplets after the mutation are displaced.
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 Frameshift mutations |
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Explain why an insertion of 3 nucleotides is less likely to result in a deleterious effect than an insertion of a single nucleotide.
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Restores the original reading frame.
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Fill in the blanks for these other types of mutations:1. A _____ removes a chromosomal segment.2. A _____ repeats a segment.3. A(n) _____ reverses a segment within a chromosome.4. A _____ moves a segment from one chromosome to another, nonhomologous one.
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 1. A deletion removes a chromosomal segment.2. A duplication repeats a segment.3. An inversion reverses a segment within a chromosome.4. A translation moves a segment from one chromosome to another nonhomologous one. |
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What are the two ways that mutations occur?
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Spontaneous mutation and induced mutation
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What is spontaneous mutation?
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Occur in the absence of mutation-causing agents (for ex. DNA polymerase makes a mistake during replication)• ~10^-6 -> 1 mutation per million replicated genes
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What is induced mutation?
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Caused by mutagens-chemical or physical agents in the environment that significantly increase the frequency of mutations• increases mutation rate by 10-1000x
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What are some examples of mutagens?
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What are deaminating agents?
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 Removal of NH2 group, altering base pairing. 'A' pairs with 'C' instead of 'T'. |
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What are intercalating agents?
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 Insert between bases in DNA, can cause frameshift mutations. |
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What are base analogs?
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 These mimic normal DNA bases. Can cause a T-A to change to a C-G. |
