Textbook Question
List and describe the function of the ten subunits constituting DNA polymerase III. Distinguish between the holoenzyme and the core enzyme.
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Ch. 11 - DNA Replication and Recombination
Klug12th EditionConcepts of Genetics ISBN: 9780135564776
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Table of contents
- Ch. 1 - Introduction to Genetics17
- Ch. 2 - Mitosis and Meiosis36
- Ch. 3 - Mendelian Genetics51
- Ch. 4 - Extensions of Mendelian Genetics74
- Ch. 5 - Chromosome Mapping in Eukaryotes51
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages46
- Ch. 7 - Sex Determination and Sex Chromosomes33
- Ch. 8 - Chromosome Mutations: Variation in Number and Arrangement40
- Ch. 9 - Extranuclear Inheritance31
- Ch. 10 - DNA Structure and Analysis43
- Ch. 11 - DNA Replication and Recombination44
- Ch. 12 - DNA Organization in Chromosomes30
- Ch. 13 - The Genetic Code and Transcription54
- Ch. 14 - Translation and Proteins47
- Ch. 15 - Gene Mutation, DNA Repair, and Transposition41
- Ch. 16 - Regulation of Gene Expression in Bacteria29
- Ch. 17 - Transcriptional Regulation in Eukaryotes41
- Ch. 18 - Post-transcriptional Regulation in Eukaryotes33
- Ch. 19 - Epigenetics33
- Ch. 20 - Recombinant DNA Technology44
- Ch. 21 - Genomic Analysis36
- Ch. 22 - Applications of Genetic Engineering and Biotechnology36
- Ch. 23 - Developmental Genetics37
- Ch. 24 - Cancer Genetics34
- Ch. 25 - Quantitative Genetics and Multifactorial Traits54
- Ch. 26 - Population and Evolutionary Genetics45
Chapter 11, Problem 10
Kornberg showed that nucleotides are added to the 3' end of each growing DNA strand. In what way does an exposed 3'-OH group participate in strand elongation?
Verified step by step guidance1
Understand that DNA strand elongation occurs by adding nucleotides to the 3' end of the growing strand, which means the 3'-OH group is crucial for this process.
Recognize that the 3'-OH group acts as a nucleophile, meaning it donates an electron pair to form a new chemical bond during DNA synthesis.
During strand elongation, the 3'-OH group attacks the incoming nucleotide's 5'-phosphate group, facilitating the formation of a phosphodiester bond.
This phosphodiester bond links the 3' carbon of the existing nucleotide to the 5' carbon of the new nucleotide, extending the DNA strand in the 5' to 3' direction.
Therefore, the exposed 3'-OH group is essential because it provides the reactive site that allows DNA polymerase to add new nucleotides and elongate the DNA strand.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
DNA Strand Elongation Directionality
DNA synthesis occurs in the 5' to 3' direction, meaning nucleotides are added to the 3' end of the growing strand. This directionality is crucial because DNA polymerase can only add nucleotides to a free 3'-OH group, ensuring proper strand growth.
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05:02
Directionality
Role of the 3'-OH Group in DNA Polymerization
The exposed 3'-OH group acts as a nucleophile that attacks the incoming nucleotide's 5'-phosphate group, forming a phosphodiester bond. This chemical reaction links nucleotides together, enabling the elongation of the DNA strand.
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06:25DNA Structure
Function of DNA Polymerase in Strand Elongation
DNA polymerase catalyzes the addition of nucleotides to the 3' end by facilitating the formation of phosphodiester bonds between the 3'-OH of the growing strand and the 5'-phosphate of the incoming nucleotide. This enzyme ensures high fidelity and processivity during DNA replication.
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Related Practice
Textbook Question
How did Kornberg assess the fidelity of DNA polymerase I in copying a DNA template?
Textbook Question
Which characteristics of DNA polymerase I raised doubts that its in vivo function is the synthesis of DNA leading to complete replication?
Textbook Question
In Kornberg's initial experiments, it was rumored that he grew E. coli in Anheuser-Busch beer vats. (Kornberg was working at Washington University in St. Louis.) Why do you think this might have been helpful to the experiment?
Textbook Question
What was the significance of the polA1 mutation?
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Textbook Question
Summarize and compare the properties of DNA polymerase I, II, and III.
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