Consider a three-base sequence within the coding region in the DNA template stra
ID: 214723 • Letter: C
Question
Consider a three-base sequence within the coding region in the DNA template strand: 5'-...123...-3', in which 1, 2, and 3 refer to the relative positions of deoxyribonucleotides within a codon. What would be the effects of a point mutation that would change one pyrimidine for another at position 2?
1. (True/False) This mutation will always result in an altered amino acid sequence in the mutant protein compared to the original protein.
2. (True/False) The mutant amino acid, if changed, is more likely to be similar to the original amino acid than not. (Here, similar means that the two amino acids are both hydrophobic, or that both are basic, acidic, or polar. If an amino acid does not change between the mutant and the original, then count the mutant as similar.)
3. (True/False) Considering the above results, it is likely that more than half of the mutations would significantly affect the function of the protein in which it is located if the mutant amino acid is a key determinant of the protein's function.
Explanation / Answer
10. This mutation will always result in an altered amino acid sequence in the mutant protein compared to the original protein. ---> FALSE
Mutation is the change in original base pair sequences that convert one allele to another allele. It is a continual source of genetic variation. Mutations can be harmful, beneficiary, or neutral.
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).