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23 Cards in this Set
- Front
- Back
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Mutations at the DNA level only manifest themselves phenotypically through ___ and ____ ____.
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RNA and protein expression
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What do mutations do to promotors?
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-Decrease the ability of promoters to bind to specific protein factors needed for transcription (i.e., transcription factors)
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What mutations are known to increase transcription?
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-G-gamma and A-gamma genes that result in persistent expression of fetal hemoglobin in adults
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What is an example of a mutation in the enhancer regions?
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-Beta-globin gene cluster
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Missense Mutation
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Single base substitution that causes a codon change within a coding sequence, resulting in the replacement of a different amino acid in the protein product
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Where do missense mutations commonly occur?
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-1st or 2nd bases of a codon
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Silent Mutation (aka Synonymous Mutation)
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Single nucleotide substitution, especially when occurring at the 3rd base of a codon that often do not result in an amino acid mutation
-MAY EFFECT SPLICING |
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Divisions of Non-synomous substitutions
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-Conservative Substitution
-Non-conservative Substitution |
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Conservative Substitution (Division of Non-synonomous substitution)
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-WHen an amino acid is replaced by another amino acid that is similar in chemical property
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Non-conservative Substitution (Division of Non-synonomous substitution)
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-When an amino acid is replaced by another amino acid that is dissimilar in chemical property
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Nonsense Mutation
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Single base substitution that results in a codon change within a coding sequence, resulting in the replacement of an amino acid with a stop codon
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What can a nonsense mutation lead to?
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-Unstable mRNA
-Truncated polypeptide -Exon skipping |
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Unstable mRNA (Consequence of nonsense mutation)
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-The most common consequence of a premature termination codon at least 50 bases upstream of the last splice junction rapidly degraded in vivo by a process called nonsense mediated decay
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Truncated polypeptide (Consequence of nonsense mutation)
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-Rare Event
-Particularly common in genes that lack introns, suggesting that the splicing mechanism plays a role in nonsense-mediated decay |
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Exon skipping (consequence of nonsense mutation)
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-Rare Event
-The occurrence of a truncated polypeptide is mitigated by alternative splicing that eliminated the premature stop codon from the RNA |
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Frameshift mutation
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-a change in DNA sequence, most commonly a small deletion or insertion of a non-mutliple of 3 nucleotides, that results in the alteration of the reading frame
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What is a common result of a frameshift mutation?
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-Alteration of the location of the stop codon, either proximal or distal to the normal stop codon
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What is a common result of nonsense mutation?
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-Unstable mRNA
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Codon deletions or insertions will result in what?
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-the insertion or deletion of one or more amino acids with preservation of the reading frame
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Splicing Mutations
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-Nucleotide substitution of splice donor or acceptor sites results in abnormal splicing of RNA transcript
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A type of splicing mutation involveds the creation of new ____ ______or activation of ______ _____ _____ resulting in new patterns of RNA splicing.
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-Splice Sites
-"cryptic" splice sites |
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Mutations in the ______ ___ and _____ ____ ___of RNA usually lead to instability of mRNA.
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-Polyadenylation site of RNA
-3'-untranslated regions |
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Mutations in __ ___ ___ result in poor translational initiation.
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-5' untranslated regions
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