Match each of the following protein functions during DNA replication with its correct protein on the figure: – Unwinds the DNA double helix – Prevents the unwound DNA strand from reannealing – Helicase – Topoisomerase – Initiates and continues the DNA replication – DNA polymerase – Creates the RNA primer – Primase – Synthesizes new DNA strands – DNA ligase – Exonuclease
The Correct Answer and Explanation is:
Correct Matching of Protein Functions with Figure Labels:
Based on the image and the provided descriptions, the correct matches for each protein function in DNA replication are:
- A: Unwinds the DNA double helix → Top right protein (Helicase)
- B: Prevents the separated DNA strand from reannealing → Small proteins near single strands (Single-strand binding proteins – SSBPs)
- C: Helps DNA polymerase to be processive → Sliding clamp (Clamp loader/sliding clamp complex)
- D: Creates the RNA primer → Primase
- E: Synthesizes a new DNA strand → DNA Polymerase (Large central enzyme)
Explanation:
DNA replication is a critical process in cellular division, ensuring that each daughter cell receives an exact copy of the DNA. It involves a coordinated effort by various enzymes and proteins that fulfill specific roles.
Helicase is the enzyme that initiates the process by unwinding the double-stranded DNA. This unwinding breaks the hydrogen bonds between the base pairs, forming two single strands that serve as templates for replication. In the diagram, helicase is labeled at the replication fork (letter A).
Once the strands are separated, single-strand binding proteins (SSBPs) immediately bind to the single-stranded DNA to prevent the two strands from reannealing or forming secondary structures. These are labeled as letter B in the figure.
Primase (letter D) synthesizes a short RNA primer complementary to the DNA template. This primer provides the 3′ hydroxyl group necessary for DNA polymerase (letter E) to begin synthesizing the new DNA strand.
DNA polymerase carries out the elongation of the new DNA strand by adding nucleotides in the 5′ to 3′ direction. It is highly processive due to the aid of a sliding clamp (letter C), which encircles the DNA and keeps the polymerase attached, increasing replication efficiency.
Together, these components ensure rapid and accurate DNA replication, essential for cell survival and division.
