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Questions and Answers
What is the function of DNA replication?
Which direction does DNA polymerase synthesize the new strand?
What is the role of DNA helicase in replication?
Why do DNA polymerases require an RNA primer?
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What is the role of DNA ligase in replication?
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What is meant by semi-conservative replication?
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Which enzyme catalyzes the removal of supercoils formed during DNA unwinding?
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What is the function of DNA topoisomerase I in DNA replication?
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Which enzyme is responsible for producing progressive unwinding of the DNA double helix at the replication fork?
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What is the role of single-strand binding (SSB) proteins in DNA replication?
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Which enzyme is responsible for forming RNA primers during DNA replication?
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What is the function of DNA polymerase III in DNA replication?
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Which characteristic property of DNA polymerase III allows it to synthesize both strands of DNA at a high rate?
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Which enzyme acts by making transient breaks in both DNA strands during DNA replication?
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What is the role of dna A in DNA replication in prokaryotes?
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What is the function of DNA gyrase in bacteria and plants?
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Study Notes
DNA Replication Overview
- DNA replication is essential for cell division, ensuring that each daughter cell receives an exact copy of the DNA.
- It is a semi-conservative process, meaning each new double helix contains one original strand and one newly synthesized strand.
Direction of Synthesis
- DNA polymerase synthesizes new strands in the 5' to 3' direction, adding nucleotides to the 3' end of the growing strand.
Role of DNA Helicase
- DNA helicase unwinds the double helix, separating the two strands to allow for replication to occur.
Requirement for RNA Primer
- DNA polymerases cannot initiate synthesis on a bare template strand; they require a short RNA primer to provide a starting point for DNA synthesis.
Function of DNA Ligase
- DNA ligase seals gaps between Okazaki fragments on the lagging strand, ensuring the continuity of the DNA molecule.
Semi-conservative Replication
- In semi-conservative replication, each parent strand serves as a template for a new complementary strand, resulting in two DNA molecules, each with one old and one new strand.
Enzyme for Supercoil Removal
- DNA topoisomerase is responsible for relieving the supercoiling tension that occurs ahead of the replication fork during DNA unwinding.
Function of DNA Topoisomerase I
- DNA topoisomerase I creates transient single-strand breaks in DNA to alleviate torsional strain generated during replication.
Enzyme for Progressive Unwinding
- DNA helicase actively unwinds the DNA double helix at the replication fork, allowing access for other enzymes involved in replication.
Role of Single-Strand Binding (SSB) Proteins
- SSB proteins stabilize unwound single strands of DNA, preventing them from re-annealing or forming secondary structures during replication.
RNA Primer Formation
- The enzyme primase synthesizes short RNA primers necessary for initiating DNA replication.
Function of DNA Polymerase III
- DNA polymerase III is the primary enzyme responsible for synthesizing new DNA strands during replication, working quickly and effectively on both leading and lagging strands.
Characteristics of DNA Polymerase III
- The high processivity of DNA polymerase III allows it to synthesize DNA at a rapid rate, making it efficient for replication.
Enzyme for Transient Breaks
- DNA topoisomerase II (or gyrase in bacteria) makes transient breaks in both strands of DNA, facilitating the untangling of DNA during replication.
Role of DnaA in Prokaryotes
- DnaA is involved in the initiation of DNA replication in prokaryotes by binding to the origin of replication, facilitating the unwinding of DNA.
Function of DNA Gyrase
- DNA gyrase is a type of topoisomerase that introduces negative supercoils into DNA, helping to relieve torsional strain in bacterial and plant DNA during replication.
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Description
Test your knowledge on DNA replication in prokaryotes with this quiz based on the lecture by Dr. George N. B. Morcos. Explore the proteins, enzymes, and synthesis of leading and lagging strands involved in DNA replication.
