AP BIOLOGY

LABORATORY REVIEW

MOLECULAR BIOLOGY

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In which way does RNA differ from DNA?
A
RNA is double stranded
B
RNA is single stranded
C
RNA is found only in the nucleus
D
RNA contains nitrogenous bases
Explanation: 

Detailed explanation-1: -DNA is a double-stranded molecule that has a long chain of nucleotides. RNA is a single-stranded molecule which has a shorter chain of nucleotides. DNA replicates on its own, it is self-replicating. RNA does not replicate on its own.

Detailed explanation-2: -Unlike DNA, RNA in biological cells is predominantly a single-stranded molecule. While DNA contains deoxyribose, RNA contains ribose, characterised by the presence of the 2′-hydroxyl group on the pentose ring (Figure 5). This hydroxyl group make RNA less stable than DNA because it is more susceptible to hydrolysis.

Detailed explanation-3: -There are two differences that distinguish DNA from RNA: (a) RNA contains the sugar ribose, while DNA contains the slightly different sugar deoxyribose (a type of ribose that lacks one oxygen atom), and (b) RNA has the nucleobase uracil while DNA contains thymine.

Detailed explanation-4: -Unlike DNA, however, RNA is most often single-stranded. An RNA molecule has a backbone made of alternating phosphate groups and the sugar ribose, rather than the deoxyribose found in DNA. Attached to each sugar is one of four bases: adenine (A), uracil (U), cytosine (C) or guanine (G).

Detailed explanation-5: -DNA is generally double-stranded and RNA is generally single-stranded (though both can exist in either form). Prokaryotes contain both DNA and RNA.

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