Podcast
Questions and Answers
What is the primary function of genetic material?
What is the primary function of genetic material?
- To facilitate cell division.
- To produce energy for cellular functions.
- To destroy unwanted genetic material.
- To express hereditary traits. (correct)
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?
- Transformative replication.
- Conservative replication.
- Semi-conservative replication. (correct)
- Dispersive replication.
What is the role of DNA helicase during DNA replication?
What is the role of DNA helicase during DNA replication?
- To create RNA primers.
- To unzip the DNA double helix. (correct)
- To remove RNA primers.
- To add nucleotides.
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?
What is the function of topoisomerase during DNA replication?
What is the function of topoisomerase during DNA replication?
Which enzyme is primarily responsible for adding nucleotides during DNA synthesis?
Which enzyme is primarily responsible for adding nucleotides during DNA synthesis?
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?
What are Okazaki fragments associated with in DNA replication?
What are Okazaki fragments associated with in DNA replication?
What is the final result of DNA replication?
What is the final result of DNA replication?
Flashcards
DNA Replication
DNA Replication
The process by which DNA replicates, ensuring that genetic information is accurately passed from one generation to the next.
Conservative Replication
Conservative Replication
A model of DNA replication where one parental DNA strand remains intact, while the other is used as a template to create a completely new strand.
Semi-Conservative Replication
Semi-Conservative Replication
A model of DNA replication where each new DNA molecule consists of one original strand and one newly synthesized strand.
Dispersive Replication
Dispersive Replication
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Replication Fork
Replication Fork
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DNA Helicase
DNA Helicase
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Topoisomerase
Topoisomerase
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RNA Primase
RNA Primase
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DNA Polymerase III
DNA Polymerase III
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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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