Which of the following statements about dna synthesis at the replication fork pf a replicating dna molecule is false
The Correct Answer and Explanation is:
The false statement about DNA synthesis at the replication fork of a replicating DNA molecule is:
“The sequence of each newly synthesized single strand is identical to that of the parental single strand that served as its template.”
Explanation:
DNA synthesis at the replication fork occurs in a highly regulated manner to ensure that genetic information is accurately copied. Below are the facts about DNA replication:
- Nucleotides are added at the 3′ ends of all the new strands: This is true. DNA polymerase adds nucleotides in the 5′ to 3′ direction on the newly synthesized strand. Since DNA is anti-parallel, the leading strand is synthesized continuously, while the lagging strand is synthesized in fragments (Okazaki fragments).
- The sequence of each newly synthesized single strand is identical to that of the parental single strand that served as its template: This is false. The newly synthesized strand is complementary to the template strand, not identical to it. For example, if the template strand has an adenine (A), the new strand will have thymine (T), and if the template has cytosine (C), the new strand will have guanine (G).
- DNA replication requires RNA primers: This is true. DNA polymerase cannot initiate the synthesis of a new strand without a primer. The RNA primer is synthesized by primase, providing the 3′ OH group required for DNA polymerase to begin adding nucleotides.
- Prokaryotes do not have telomerase: This is true. Telomerase is an enzyme that extends the telomeres (the ends of chromosomes) and is mainly active in eukaryotic cells. Prokaryotes generally do not have telomeres, as they typically have circular chromosomes.
- DNA helicase and DNA ligases are required for DNA replication: This is true. DNA helicase unwinds the double helix, and DNA ligase is essential for sealing the nicks between the Okazaki fragments on the lagging strand.
In summary, the sequence of the newly synthesized strand is complementary to the template strand, not identical.
