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Questions and Answers
What is the primary function of genetic material?
What is the primary function of genetic material?
What type of DNA replication was validated by the Meselson and Stahl experiment?
What type of DNA replication was validated by the Meselson and Stahl experiment?
What is the role of DNA helicase during DNA replication?
What is the role of DNA helicase during DNA replication?
How does the leading strand differ from the lagging strand in DNA replication?
How does the leading strand differ from the lagging strand in DNA replication?
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What is the function of topoisomerase during DNA replication?
What is the function of topoisomerase during DNA replication?
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Which enzyme is primarily responsible for adding nucleotides during DNA synthesis?
Which enzyme is primarily responsible for adding nucleotides during DNA synthesis?
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During DNA replication, which enzyme removes RNA primers and replaces them with DNA?
During DNA replication, which enzyme removes RNA primers and replaces them with DNA?
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What are Okazaki fragments associated with in DNA replication?
What are Okazaki fragments associated with in DNA replication?
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What is the final result of DNA replication?
What is the final result of DNA replication?
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Study Notes
Central Dogma Concept
- Genetic material stores and passes genetic information for the next generation.
- It expresses hereditary traits.
DNA Replication Models
- Conservative: One helix with old DNA and one with new DNA is produced.
- Semi-conservative: DNA helices are produced with one old and one new strand (proven by Meselson-Stahl).
- Dispersive: DNA helices have mixed segments of old and new DNA.
Meselson and Stahl Experiment
- Setup: E. coli was grown in heavy nitrogen (15N) then switched to light nitrogen (14N). DNA densities were analyzed across generations.
- Conclusion: DNA replicates semi-conservatively.
Steps in DNA Replication
Unwinding
- DNA helicase unwinds the double helix at the replication fork.
Stabilization
- Topoisomerase reduces tension caused by unwinding.
- Single-strand binding proteins prevent the strands from recoiling.
Strand Synthesis
- Leading strand: Continuous synthesis in 5' to 3' direction, using an RNA primer and DNA polymerase III.
- Lagging strand: Discontinuous synthesis using Okazaki fragments . RNA primers, DNA polymerase I, and DNA ligase seal the gaps.
Final Result
- Two semi-conservative DNA molecules are produced, each with one original and one newly formed strand.
Enzymes Involved
- DNA Helicase: Unwinds the DNA.
- Topoisomerase: Relieves tension during unwinding.
- RNA Primase: Creates RNA primers.
- DNA Polymerase III: The main enzyme adding nucleotides.
- DNA Polymerase I: Removes RNA primers and replaces them with DNA.
- DNA Ligase: Joins Okazaki fragments on the lagging strand.
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Description
Explore the key concepts of DNA replication, including the central dogma, different replication models, and the groundbreaking Meselson-Stahl experiment. This quiz will test your understanding of the steps involved in DNA replication and the mechanisms at play.
