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Questions and Answers
What is the role of helicase in DNA replication?
What is the role of helicase in DNA replication?
Helicase is the enzyme that unwinds and unzips the two strands of DNA by breaking the hydrogen bonds between the bases.
How does DNA polymerase differ in its operation on the leading and lagging strands?
How does DNA polymerase differ in its operation on the leading and lagging strands?
DNA polymerase copies DNA in a 5’-3’ direction on both strands, but on the leading strand, it is continuous, while on the lagging strand, it works in short segments known as Okazaki fragments.
What is the purpose of primers in DNA replication?
What is the purpose of primers in DNA replication?
Primers serve as starting points for DNA synthesis, providing a 3' end for DNA polymerase to attach nucleotides.
Describe the function of DNA ligase in the replication process.
Describe the function of DNA ligase in the replication process.
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What is the significance of the origins of replication during DNA replication?
What is the significance of the origins of replication during DNA replication?
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Study Notes
DNA Replication Overview
- DNA replication occurs in both eukaryotes and prokaryotes
- In eukaryotes, replication occurs inside the nucleus
- Occurs during interphase, before cell division
- Daughter cells receive a copy of the DNA
- Enzymes are key components, speeding up chemical reactions in the body, building and breaking down substances
- Starts at origins, locations with specific DNA sequences
Key Replication Enzymes
- Helicase: The "unzipping" enzyme; breaks hydrogen bonds holding DNA strands together.
- Single-Strand Binding Proteins (SSBs): Keep the separated DNA strands apart.
- Topoisomerase: Prevents the DNA from supercoiling ahead of the replication fork.
- Primase: The "instructor"; directs where DNA polymerase will build. Creates short RNA primers that provide a starting point for DNA polymerase.
- DNA Polymerase: The "builder"; copies DNA molecules, constructing new DNA strands. DNA polymerase can only move in the 5' to 3' direction.
- Ligase: The "gluer"; joins DNA fragments together.
Leading and Lagging Strands
- Leading strand synthesizes continuously in the 5' to 3' direction, following the replication fork.
- Lagging strand synthesizes discontinuously in segments called Okazaki fragments. It starts at a new location on the template strand behind the replication fork and synthesizes in the 5' to 3' direction away from the replication fork.
- Okazaki fragments are joined by ligase.
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Description
Explore the fundamental concepts of DNA replication, including its significance in both eukaryotic and prokaryotic cells. This quiz will cover essential replication enzymes like helicase and DNA polymerase, as well as the overall process that ensures daughter cells receive accurate DNA copies during cell division.
