Questions and Answers
Which direction does the leading strand grow in DNA replication?
5' to 3'
What is the direction of growth of the lagging strand in DNA replication?
3' to 5'
How are Okazaki fragments joined together in DNA replication?
By DNA ligase
Which model describes the synthesis of the lagging strand in DNA replication?
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What is the role of DNA polymerase I in DNA replication?
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Which DNA repair mechanism is responsible for removing larger mutations that distort DNA structure?
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What is the function of the Telomerase enzyme in DNA replication?
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Which enzyme is responsible for unwinding the double helix during DNA replication?
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Which type of DNA repair process is used to correct DNA mutations caused by exposure to UV radiation?
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During DNA replication, in which direction is the leading strand synthesized?
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Which protein is responsible for binding to the single-stranded DNA created by DNA helicase during DNA replication?
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Which enzyme is responsible for synthesizing a short RNA primer during DNA replication?
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Which type of DNA repair process is used to correct DNA mutations caused by errors during DNA replication?
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Which enzyme is responsible for removing RNA primers and replacing them with DNA during DNA replication?
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Which repair pathway requires sister chromatids and occurs during S and G2 phase?
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Which repair pathway is used by post mitotic cells and cycling cells in G1?
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Which repair pathway involves removing altered bases, removing the phosphoribose backbone, filling in the gap, and sealing the strand?
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Which repair pathway uses a repair template and requires sister chromatids?
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Which repair pathway does not use a repair template and directly ligates broken ends?
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Which repair pathway recognizes mis-incorporated bases, removes them, and replaces them with the correct bases?
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Which repair pathway removes incorrect bases with a few surrounding bases and replaces them with the correct bases?
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Which repair pathway is responsible for repairing DNA double strand breaks?
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Which repair pathway binds to the double stranded break and recruits necessary polymerase and ligase to repair the break?
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Which type of DNA mutation involves the substitution of a single base?
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Which repair process is responsible for correcting base-pairing errors?
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Which repair process is used to fix bulky lesions caused by UV radiation?
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Which repair process involves the removal of RNA primers and their replacement with DNA during DNA replication?
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Which type of DNA mutation involves the addition of extra bases?
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Which repair process involves the joining of Okazaki fragments in DNA replication?
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Which repair process does not use a repair template and directly ligates broken ends?
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Which repair process is used to correct DNA mutations caused by exposure to mutagens?
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Which repair process is used to correct DNA mutations caused by errors during DNA replication?
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Which repair process involves the alteration of the reading frame in DNA?
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Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?
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Which nitrogenous base pairs with guanine in DNA?
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What is the function of telomeres in eukaryotic chromosomes?
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Which enzyme is responsible for unwinding the DNA double helix during DNA replication?
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What are the three parts of a nucleotide in DNA?
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Which enzyme synthesizes RNA primers during DNA replication?
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Which nitrogenous base pairs with thymine in DNA?
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Which enzyme builds new DNA strands during DNA replication?
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What is the structure of DNA?
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Which nitrogenous base pairs with adenine in DNA?
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Which enzyme is responsible for unwinding the DNA double helix during DNA replication?
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What is the function of telomeres in eukaryotic chromosomes?
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Which enzyme builds new DNA strands during DNA replication?
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Which repair pathway involves removing altered bases, removing the phosphoribose backbone, filling in the gap, and sealing the strand?
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During DNA replication, in which direction is the leading strand synthesized?
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Which nitrogenous base pairs with adenine in DNA?
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Which type of DNA mutation involves the substitution of a single base?
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Which enzyme is responsible for synthesizing a short RNA primer during DNA replication?
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Which repair pathway is responsible for removing incorrect bases with a few surrounding bases and replacing them with the correct bases?
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What is the primary function of telomerase in DNA replication?
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Which repair pathway is used to fix larger mutations that distort DNA structure?
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Which repair pathway is responsible for repairing DNA double strand breaks?
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What is the role of error checking and repair systems in maintaining the integrity of the genome?
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Study Notes
DNA Replication and Structure
- The leading strand grows continuously in the 5' to 3' direction during DNA replication.
- The lagging strand is synthesized discontinuously in short fragments, known as Okazaki fragments, in the 3' to 5' direction.
- Okazaki fragments are joined together by the enzyme DNA ligase.
- The lagging strand synthesis model is described by the discontinuous replication model.
Enzymatic Roles in DNA Replication
- DNA polymerase I is responsible for removing RNA primers and replacing them with DNA.
- DNA helicase unwinds the double helix structure of DNA, creating single-stranded DNA.
- RNA primase synthesizes short RNA primers required for DNA synthesis.
- DNA polymerase synthesizes new DNA strands and builds in the 5' to 3' direction.
- Telomerase adds repetitive sequences to the ends of chromosomes to prevent degradation.
DNA Repair Mechanisms
- Nucleotide excision repair (NER) corrects larger mutations that distort DNA structure, often caused by UV radiation.
- Base excision repair (BER) involves the removal of altered bases and the phosphoribose backbone, filling in the resultant gap, and sealing the strand.
- Homologous recombination (HR) requires sister chromatids for accurate repair and occurs during the S and G2 phases of the cell cycle.
- Non-homologous end joining (NHEJ) does not require a repair template, directly ligating broken ends together.
- Mismatch repair (MMR) recognizes mis-incorporated bases, removes them, and replaces them with the correct ones.
- The proofreading function serves to correct base-pairing errors and improve fidelity.
Types of DNA Mutations
- Point mutation involves the substitution of a single base pair.
- Insertion mutation reflects the addition of extra bases, altering reading frames.
- Telomeres, located at the ends of eukaryotic chromosomes, protect against degradation and ensure chromosome stability.
Summary of Key Enzymes and Their Functions
- DNA polymerase: Main enzyme responsible for synthesizing new DNA strands.
- DNA ligase: Joins Okazaki fragments on the lagging strand during replication.
- DNA helicase: Unwinds the double-stranded DNA helix.
- RNA primase: Synthesizes RNA primers to initiate replication.
Nitrogenous Base Pairing
- Guanine pairs with cytosine.
- Adenine pairs with thymine.
Nucleotide Structure
- Nucleotides consist of a nitrogenous base, a sugar (deoxyribose in DNA), and a phosphate group.
Error Checking and Repair Systems
- Error checking and repair systems are crucial for maintaining genomic integrity, correcting errors during DNA replication, and preventing mutation accumulation.
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Description
Test your knowledge on DNA replication with this informative quiz! Learn about the process of elongation, the directions of growth for the leading and lagging strands, and the role of ligase in joining Okazaki fragments. Don't miss out on understanding the trombone model for lagging strand synthesis as well.
