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Multiple Choice
Which enzyme is required to initiate DNA synthesis on a bare template strand?
A
Ligase
B
RNA primase
C
DNA polymerase
D
Helicase
Verified step by step guidance
1
Understand the process of DNA replication: DNA replication is the process by which a cell duplicates its DNA before cell division. It involves several enzymes that work together to ensure accurate replication.
Identify the role of each enzyme listed: Ligase is responsible for joining Okazaki fragments on the lagging strand. DNA polymerase synthesizes new DNA strands by adding nucleotides. Helicase unwinds the DNA double helix. RNA primase synthesizes a short RNA primer to provide a starting point for DNA polymerase.
Focus on the initiation of DNA synthesis: DNA polymerase cannot start synthesizing a new DNA strand on its own; it requires a primer to provide a free 3'-OH group.
Determine which enzyme provides the primer: RNA primase synthesizes a short RNA primer complementary to the DNA template, providing the necessary 3'-OH group for DNA polymerase to begin DNA synthesis.
Conclude that RNA primase is the enzyme required to initiate DNA synthesis on a bare template strand, as it provides the primer needed for DNA polymerase to start adding nucleotides.