You are an Honours student at Sandstone University and one day, you were in the tearoom chatting with some of the other Honours students. During a discussion of a genetics project, one of the students told the group that technically there is no such thing as a continuous strand in mammalian DNA replication. They said that if you ignore size, both the leading and lagging strands have Okazaki fragments. Is the Honours student correct? Explain your answer.
Added by Walter P.
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Step 1: In mammalian DNA replication, the leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously in short fragments called Okazaki fragments. Show more…
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In DNA replication, the leading and the lagging strands are different in that A. the leading strand is elongated in the same direction as the movement of the replication fork, and the lagging strand is elongated in the opposite direction. B. the leading strand is elongated by adding nucleotides to the 3’ end of the new strand, and the lagging strand is elongated by adding nucleotides to the 5’ end. C. the lagging strand is elongated continuously, whereas the leading strand is elongated in short fragments. D. the leading strand is retained in the new DNA, whereas the lagging strand is discarded and degraded by hydrolytic enzymes. E. the leading strand is the template for the lagging strand.
Mystique T.
Because all DNA polymerases replicate and synthesize DNA, accomplished in the 5' to 3' direction with the use of DNA templates, the mechanisms of parental strand replication can be either continuous or discontinuous. Continuous replication refers to the synthesis of DNA in a continuous manner, while discontinuous replication involves the synthesis of DNA in short fragments called Okazaki fragments. Primase is responsible for synthesizing RNA primers on the lagging strand, and single-strand binding proteins help stabilize the single-stranded DNA. The sliding clamp helps to keep the DNA polymerase attached to the template strand during replication. DNA helicase unwinds the DNA double helix, allowing for replication to occur. DNA ligase is responsible for joining the Okazaki fragments together.
Madhur L.
a. Look at the figure above. Explain why it is necessary for Okazaki fragments to be formed as the lagging strand is produced (instead of a continuous strand). b. If the DNA polymerase in the figure above could only bind to the lower template strand, under what conditions(s) would it be able to produce a leading strand?
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