AP BIOLOGY

HEREDITY

MUTATIONS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
True or False:The total number of nucleotides is changed during a substitution.
A
True:The total number of nucleotides increases.
B
False:The total number of nucleotides stays the same.
C
True:The total number of nucleotides decreases.
D
False:Not enough information is given.
Explanation: 

Detailed explanation-1: -With base substitution mutations, only a single nucleotide within a gene sequence is changed, so only one codon is affected (Figure 1).

Detailed explanation-2: -Changing a single nucleotide will change the amino acid sequence, which can impact how the protein it forms will look and act.

Detailed explanation-3: -The nuclear genome comprises approximately 3 200 000 000 nucleotides of DNA, divided into 24 linear molecules, the shortest 50 000 000 nucleotides in length and the longest 260 000 000 nucleotides, each contained in a different chromosome.

Detailed explanation-4: -However, base substitutions do not always cause a change in the sequence of amino acids. This is due to the degeneracy in the genetic code; the fact that there are 64 different possible triplets but only 20 different amino acids, some must code for the same amino acid.

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