Multiple Choice
Which nitrogenous base is not found in RNA?
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7. DNA and Chromosome Structure
DNA Structure
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In the double helix structure of DNA, how many hydrogen bonds hold adenine and thymine together?
A
2
B
1
C
4
D
3
Verified step by step guidance1
Recall that DNA base pairing follows Chargaff's rules, where adenine (A) pairs specifically with thymine (T), and guanine (G) pairs with cytosine (C).
Understand that the stability of these base pairs is due to hydrogen bonds formed between the nitrogenous bases.
Know that adenine and thymine are connected by hydrogen bonds, but the number of these bonds differs from the guanine-cytosine pair.
Remember that adenine and thymine are held together by exactly two hydrogen bonds, which is fewer than the three hydrogen bonds holding guanine and cytosine together.
Therefore, the number of hydrogen bonds between adenine and thymine in the DNA double helix is 2.
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