Video Transcript
Which of the following is not a type of genetic mutation? (A) Differentiation, (B) deletion, (C) insertion, or (D) substitution.
DNA is the molecule that stores genetic information in the cell. It consists of many nucleotides bound together to form the characteristic double-helix structure. Each nucleotide consists of a phosphate group, a deoxyribose sugar, and a nitrogenous base. In DNA, there’s four kinds of nitrogenous bases: cytosine, as shown in blue; guanine, as shown in orange; adenine, as shown in green; and thymine, as shown in pink. The sequence of these nitrogenous bases can form genes that provide the instructions for different proteins.
Genetic mutations are changes in the base sequence of these genes. And because of this, mutations may cause changes in the protein’s structure. There are different kinds of mutations that can have different effects.
So suppose this is a segment of a gene that has no mutation. In an insertion mutation, an additional base is added to the sequence. Notice how this sequence is now longer than this sequence. In a deletion mutation, one base is removed from the sequence. So notice now how this sequence is shorter than this sequence. In a substitution mutation, one base is substituted for another. So we can see that there is no change in the length of the sequence. But we can see that the final cytosine has been substituted with an adenine.
If we look back at our answer choices, we can see that differentiation is not a type of genetic mutation. So the correct answer is (A), differentiation.
