Multiple Choice
Which of the following pairs of double-stranded DNA molecules would have the lower melting temperature, and why?
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7. DNA and Chromosome Structure
DNA Structure
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Which structural component is found in DNA but not in RNA?
A
Phosphate group
B
Adenine base
C
Uracil base
D
Deoxyribose sugar
Verified step by step guidance1
Recall the basic structural components of nucleic acids: both DNA and RNA are made up of a sugar, a phosphate group, and nitrogenous bases.
Identify the sugar component in DNA, which is deoxyribose, and in RNA, which is ribose. The key difference is that deoxyribose lacks one oxygen atom compared to ribose.
Examine the nitrogenous bases: DNA contains adenine, thymine, cytosine, and guanine, while RNA contains adenine, uracil, cytosine, and guanine. Note that uracil replaces thymine in RNA.
Understand that the phosphate group is common to both DNA and RNA, so it is not unique to DNA.
Conclude that the structural component unique to DNA is the deoxyribose sugar, which distinguishes it from RNA's ribose sugar.
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