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Multiple Choice
Thymine (T) makes up 28% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be guanine (G)?
A
14%
B
56%
C
22%
D
72%
Verified step by step guidance
1
Understand that in DNA, the amount of adenine (A) is equal to the amount of thymine (T), and the amount of cytosine (C) is equal to the amount of guanine (G). This is known as Chargaff's rule.
Given that thymine (T) makes up 28% of the nucleotides, adenine (A) will also make up 28% of the nucleotides.
Since adenine (A) and thymine (T) together make up 56% of the nucleotides (28% + 28%), the remaining percentage of nucleotides must be composed of cytosine (C) and guanine (G).
Calculate the percentage of nucleotides that are cytosine (C) and guanine (G) by subtracting the combined percentage of adenine (A) and thymine (T) from 100%.
Divide the remaining percentage equally between cytosine (C) and guanine (G) since they are present in equal amounts according to Chargaff's rule.