Multiple Choice
In the context of DNA replication, which enzyme activity is primarily responsible for proofreading newly synthesized DNA by removing incorrectly paired nucleotides?
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8. DNA Replication
Overview of DNA Replication
Multiple Choice
In the overview of DNA replication, helicase "unzips" which structure in the DNA molecule?
A
The hydrogen bonds between complementary nitrogenous bases that hold the two strands together
B
The phosphodiester bonds of the sugar-phosphate backbone
C
The peptide bonds between amino acids attached to DNA
D
The covalent bonds between deoxyribose and phosphate within a single nucleotide
Verified step by step guidance1
Understand the structure of DNA: DNA consists of two strands forming a double helix, where each strand is made up of nucleotides connected by covalent bonds in the sugar-phosphate backbone.
Identify the types of bonds in DNA: The sugar-phosphate backbone is held together by phosphodiester bonds, while the two strands are connected by hydrogen bonds between complementary nitrogenous bases (A-T and G-C).
Recall the role of helicase in DNA replication: Helicase is an enzyme responsible for unwinding the DNA double helix by breaking the bonds that hold the two strands together.
Determine which bonds helicase breaks: Since helicase separates the two strands, it must break the hydrogen bonds between the complementary nitrogenous bases, not the covalent phosphodiester bonds or peptide bonds.
Conclude that helicase 'unzips' the hydrogen bonds between complementary nitrogenous bases, allowing the strands to separate and serve as templates for replication.
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