Multiple Choice
In DNA, which base-pairing is incorrect under standard Watson-Crick pairing rules?
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7. DNA and Chromosome Structure
DNA Structure
Multiple Choice
Which of the following is NOT a component of DNA?
A
Nitrogenous bases (A, T, C, G)
B
Phosphate group
C
Uracil
D
Deoxyribose sugar
Verified step by step guidance1
Step 1: Understand the basic components of DNA. DNA is composed of three main parts: nitrogenous bases, a phosphate group, and a sugar molecule called deoxyribose.
Step 2: Identify the nitrogenous bases in DNA. These are adenine (A), thymine (T), cytosine (C), and guanine (G). Notice that thymine (T) is present instead of uracil.
Step 3: Recognize that uracil is a nitrogenous base found in RNA, not DNA. In RNA, uracil replaces thymine.
Step 4: Confirm that the phosphate group and deoxyribose sugar are indeed components of the DNA backbone, linking the nucleotides together.
Step 5: Conclude that since uracil is not part of DNA but part of RNA, it is the correct answer to the question asking which is NOT a component of DNA.
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