Multiple proteins are involved in DNA replication, and each protein has a unique role. Use the image to visualize some of these proteins. Note that DNA topoisomerase and DNA ligase are not shown. Match each protein to its role in DNA replication. rea Com relaxes the supercoiled DNA Answer Bank unwinds the DNA double helix 58 protein DNA polymerase II hrevents the reannealine of DNA strands relaxes the supercoiled DNA Answer Bank unwinds the DNA double helix SSB protein prevents the reannealing of DNA strands DNA polymerase III synthesizes new DNA helicase DNA ligase connects the separated DNA segments DNA topoisomerase
The Correct Answer and Explanation is:
Correct Matches:
DNA replication is a complex and highly coordinated process involving multiple specialized proteins, each contributing to the accurate duplication of the genetic material. Understanding the role of each protein helps clarify how cells ensure faithful DNA replication before cell division.
1. Helicase is a motor protein essential in the initiation of DNA replication. It binds to the origin of replication and travels along the DNA, breaking the hydrogen bonds between complementary base pairs. This “unzips” the DNA double helix, producing two single-stranded templates ready for copying. Without helicase, the DNA strands would remain coiled and inaccessible to replication machinery.
2. SSB (Single-Stranded Binding) Proteins attach to the separated DNA strands after helicase unwinds them. Their role is to stabilize these single strands and prevent them from reannealing or forming secondary structures. This stabilization is vital because single-stranded DNA is inherently unstable and can fold back on itself or rejoin with its complementary strand, halting replication.
3. DNA Polymerase III is the main enzyme responsible for synthesizing the new DNA strand by adding nucleotides in a 5’ to 3’ direction. It reads the template strand and matches complementary nucleotides, forming phosphodiester bonds to build the new strand. DNA Polymerase III is highly accurate and possesses proofreading ability to ensure fidelity.
4. DNA Topoisomerase plays a crucial role in relieving the tension generated ahead of the replication fork as the DNA unwinds. When helicase separates the strands, it introduces supercoiling (overwinding) further ahead in the helix. Topoisomerase cuts one or both DNA strands, allows them to unwind, and then reseals them, thus relaxing the supercoiled DNA and preventing strand breakage.
5. DNA Ligase is used during the later stages of replication, especially on the lagging strand. DNA polymerase creates short fragments called Okazaki fragments on the lagging strand. DNA ligase connects these fragments by forming phosphodiester bonds between them, completing the sugar-phosphate backbone of the DNA.
Together, these proteins orchestrate a smooth and precise DNA replication process essential for cell survival and genetic inheritance.
