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Multiple Choice
Which of the following correctly describes the base pairing in the structure of DNA?
A
Adenine pairs with Uracil, and Guanine pairs with Thymine
B
Adenine pairs with Cytosine, and Guanine pairs with Thymine
C
Adenine pairs with Guanine, and Thymine pairs with Cytosine
D
Adenine pairs with Thymine, and Guanine pairs with Cytosine
Verified step by step guidance
1
Step 1: Understand the structure of DNA. DNA is a double-stranded molecule composed of nucleotides, each containing a sugar (deoxyribose), a phosphate group, and a nitrogenous base. The nitrogenous bases are Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).
Step 2: Learn the base pairing rules in DNA. Base pairing occurs due to hydrogen bonding between complementary bases. Adenine (A) pairs with Thymine (T) through two hydrogen bonds, and Guanine (G) pairs with Cytosine (C) through three hydrogen bonds.
Step 3: Note that Uracil (U) is not found in DNA. Uracil is a nitrogenous base found in RNA, where it replaces Thymine (T). Therefore, Adenine does not pair with Uracil in DNA.
Step 4: Eliminate incorrect options based on the base pairing rules. For example, Adenine does not pair with Cytosine, and Guanine does not pair with Thymine. These pairings do not follow the hydrogen bonding rules.
Step 5: Confirm the correct answer. The correct base pairing in DNA is Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C). This ensures the stability and complementary nature of the DNA double helix.