AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

GENE MUTATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
If a single nucleotide were removed from a gene sequence, what would result?
A
A missense point mutation
B
A deletion frameshift mutation
C
An insertion frameshift mutation
D
A silent point mutation
Explanation: 

Detailed explanation-1: -Insertion or deletion of one or more nucleotides during replication can also lead to another type of mutation known as a frameshift mutation. The outcome of a frameshift mutation is complete alteration of the amino acid sequence of a protein.

Detailed explanation-2: -Deletion frameshift mutation, wherein one or more nucleotides are deleted in a nucleic acid, resulting in the alteration of the reading frame, i.e., reading frameshift, of the nucleic acid. Deletion is a more common mechanism for inducing the frameshift mutation that results in an altered reading frame.

Detailed explanation-3: -A frameshift variant occurs when there is an addition or loss of nucleotides that shifts the grouping and changes the code for all downstream amino acids. The resulting protein is usually nonfunctional. Insertions, deletions, and duplications can all be frameshift variants.

Detailed explanation-4: -For instance, if just one nucleotide is deleted from the sequence, then all of the codons including and after the mutation will have a disrupted reading frame. This can result in the incorporation of many incorrect amino acids into the protein.

Detailed explanation-5: -A frameshift mutation is produced either by insertion or deletion of one or more new bases. Because the reading frame begins at the start site, any mRNA produced from a mutated DNA sequence will be read out of frame after the point of the insertion or deletion, yielding a nonsense protein.

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