Leading & Lagging DNA Strands quiz Flashcards
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What is the difference in primer requirements between the leading and lagging DNA strands?
The leading strand requires only one RNA primer, while the lagging strand needs multiple primers to form Okazaki fragments.
What are Okazaki fragments and where are they found?
Okazaki fragments are short DNA segments synthesized on the lagging strand during DNA replication.
Why is the lagging strand synthesized discontinuously?
The lagging strand is synthesized discontinuously because it is built in the opposite direction of the replication fork movement.
What does the term 'antiparallel' mean in the context of DNA structure?
Antiparallel refers to the opposite orientation of the two DNA strands, with one running 5' to 3' and the other 3' to 5'.
What is the role of topoisomerase in DNA replication?
Topoisomerase relieves the strain caused by DNA supercoiling, which can inhibit DNA replication.
How does helicase contribute to DNA replication?
Helicase unwinds the two strands of template DNA by breaking the hydrogen bonds between them, creating single-stranded DNA.
What is the function of single-stranded binding proteins (SSBs) during DNA replication?
SSBs bind to single-stranded DNA to prevent it from reannealing and protect it from degradation.
Why are RNA primers necessary for DNA polymerase during DNA replication?
RNA primers provide the free 3' hydroxyl group needed for DNA polymerase to start adding nucleotides.
What is the role of DNA polymerase III in DNA replication?
DNA polymerase III adds nucleotides to the 3' end of the RNA primer, elongating the DNA strand in the 5' to 3' direction.
How does DNA polymerase I function in DNA replication?
DNA polymerase I removes RNA primers and replaces them with DNA nucleotides.
What is the function of DNA ligase in DNA replication?
DNA ligase joins Okazaki fragments together covalently on the lagging strand to create a continuous DNA strand.
What is the significance of the replication fork in DNA replication?
The replication fork is the area where the DNA double helix is unwound to allow replication of each strand.
How does the enzyme primase contribute to DNA replication?
Primase synthesizes short RNA primers that provide a starting point for DNA polymerase.
What is the role of hydrogen bonds in the structure of DNA?
Hydrogen bonds hold the two strands of DNA together by connecting complementary base pairs.
What is the function of DNA gyrase in prokaryotic DNA replication?
DNA gyrase, a type of topoisomerase, helps to relieve supercoiling ahead of the replication fork in prokaryotes.