AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

GENE MUTATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
mutation causing incorrect grouping of the remaining codons downstream from the mutation
A
insertion mutation
B
frameshift mutation
C
point mutation
D
substitution
Explanation: 

Detailed explanation-1: -If a mutation disrupts this normal reading frame, then the entire gene sequence following the mutation will be incorrectly read. This can result in the addition of the wrong amino acids to the protein and/or the creation of a codon that stops the protein from growing longer.

Detailed explanation-2: -The answer is A, frameshift mutation. In a frameshift mutation, the reading frame changes due to insertions or deletions of nucleotides. As a result, the amino acid sequence downstream of the insertion/deletion differs compared to the wild-type polypeptide sequence. Therefore, multiple amino acids in a protein change.

Detailed explanation-3: -Frameshift mutations arise when the normal sequence of codons is disrupted by the insertion or deletion of one or more nucleotides, provided that the number of nucleotides added or removed is not a multiple of three.

Detailed explanation-4: -Due to the triplet nature of codons, the amino acid sequence of a protein is determined by contiguous triplets. Therefore, a frameshift mutation leads to completely different proteins in term of chemical composition, and the closer to 5′ end of coding sequence the mutation occurs, the more protein changes it can make.

Detailed explanation-5: -Frameshift mutation can also result in the stop codon. This occurrence of the premature stop codon on mRNA will terminate the translation process, thereby, resulting in a short-length polypeptide.

There is 1 question to complete.