Key Area 2 Flashcards
What is DNA replication?
DNA replication is the process by which a cell makes an identical copy of its DNA before cell division.
When does DNA replication occur?
DNA replication occurs during the S phase of the cell cycle, before mitosis or meiosis.
What is the first step in DNA replication?
The first step is the unwinding of the double helix and separation of the two strands by the enzyme helicase, creating a replication fork.
What role does the enzyme helicase play in DNA replication?
Helicase unwinds the DNA double helix and breaks the hydrogen bonds between the complementary bases, separating the two strands.
What is the function of single-strand binding proteins (SSBs) in DNA replication?
SSBs bind to the separated DNA strands to prevent them from re-annealing or forming secondary structures during replication.
What enzyme synthesizes the new DNA strand?
DNA polymerase synthesizes the new DNA strand by adding nucleotides to the growing strand in a 5’ to 3’ direction.
What is the role of the RNA primer in DNA replication?
The RNA primer, synthesized by primase, provides a starting point for DNA polymerase to begin adding nucleotides.
What is the leading strand in DNA replication?
The leading strand is the new DNA strand that is synthesized continuously in the 5’ to 3’ direction toward the replication fork.
What is the lagging strand in DNA replication?
The lagging strand is synthesized discontinuously in short fragments called Okazaki fragments, which are later joined together by DNA ligase.
What is the role of DNA ligase in DNA replication?
DNA ligase joins the Okazaki fragments on the lagging strand, sealing the gaps between them to create a continuous DNA strand.
What does it mean that DNA replication is “semi-conservative”?
Semi-conservative replication means that each new DNA molecule consists of one original (parental) strand and one newly synthesized strand.
What is the replication fork?
The replication fork is the Y-shaped region where the DNA double helix is unwound, and new strands are being synthesized.
How does DNA replication ensure high fidelity (accuracy)?
DNA polymerase has proofreading ability, correcting any incorrect nucleotides added during replication, which helps ensure accuracy.
What happens at the origin of replication?
The origin of replication is the specific sequence in the DNA where replication begins. Multiple origins of replication occur along eukaryotic chromosomes.
Why is DNA replication important?
DNA replication is essential for the accurate transmission of genetic information to daughter cells during cell division, ensuring that each new cell has an identical copy of the DNA.
