Increasing temperature missense mutations can

Unformatted text preview: mutations can destabilize 2˚ and 3˚ structures so a protein unfolds at a lower temperature than it normally would • tyrosinase protein (→ melanin) is encoded by different alleles. • tyrosinase protein encoded by some alleles folds properly only in the coolest parts of the cat’s skin. Burmes e what are the genotypes? Siamese Different alleles with different outcomes… another example Burmese cbcb or cbcs or cb c C? C gene encodes tyrosinase… the first step in melanin synthesis what are these alleles? • cs : G302R • cb : G227W Siamese cscs or csc Other types of mutations are possible in promoter could affect transcription in intron could affect splicing pre-mRNA mature mRNA in 5’ or 3’ UTR could affect translation or ORF mRNA stability Any of these changes could change when, where, or how much protein is made “Half the amount of wt gene product is sufficient for wt phenotype” are there exceptions? yes, but they are rare rare exception #1—haploinsufficiency Half the number of protein molecules is wt/wt lof/lof not sufficient to maintain normal wild type short tail mutant tail length threshold normal tail amount of functional protein genotype: short tail wt/wt wt/lof lof/lof • is the mutant dominant or recessive? rare...
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