ally transcribes both strands of DNA during expression of a particular gene. e.
ID: 47551 • Letter: A
Question
ally transcribes both strands of DNA during expression of a particular gene. e. RNA poly merase must bind to a promoter in order to initiate transcription. 2. Which polypeptide? a. Regulation of mRNA stability )Alternative RNA splicing c. RNA interference d. Reverse transcription e. None of the above is a mechanism that allows a single gene to encode more than one 3. Which one of the following statements about mutation types is correct? a. Silent mutations are changes in DNA sequence that alter the amino acid, and they do not change the biological function of the altered sequence. b. Neutral mutations are changes in DNA sequence that are reversed by a second mutation, resulting in the same amino acid as the original, unmutated amino acid. c. Neutral mutations are changes in DNA sequence that produce synonymous codons specifying the same amino acid. d. Missense mutations alter the coding sequence. One amino acid is substituted for another. e) Missense mutations change a codon originally specifying an amino acid into a translation-termination codon.Explanation / Answer
2. b (Alternative RNA splicing allows a single gene to encode more than one polypeptide).
3. a
As the genetic code is redundant, a single amino acid may have more than one codon. For example, the amino acid glutamic acid can be coded by two different codons such as GAA and GAG. As both the triplets code for the same amino acid, no functional change in the protein synthesis occurs. These type of mutations are called as silent mutations (a type of point mutation), and it commonly occurs in several cells, but the phenotypic characters are not expressed out.
Missense mutations occur as a result of base substitutions and may result in non-functional proteins, but the results are not much disruptive like nonsense mutations (Eg: they do not result in the formation of stop codons).
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