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. 10 - DNA Replication
Klug10th EditionEssentials of GeneticsISBN: 9780135588789
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Table of contents
- Ch. 1 - Introduction to Genetics16
- Ch. 2 - Mitosis and Meiosis28
- Ch. 3 - Mendelian Genetics37
- Ch. 4 - Modification of Mendelian Ratios53
- Ch. 5 - Sex Determination and Sex Chromosomes32
- Ch. 6 - Chromosome Mutations: Variation in Number and Arrangement37
- Ch. 7 - Linkage and Chromosome Mapping in Eukaryotes36
- Ch. 8 - Genetic Analysis and Mapping in Bacteria and Bacteriophages24
- Ch. 9 - DNA Structure and Analysis38
- Ch. 10 - DNA Replication29
- Ch. 11 - Chromosome Structure and DNA Sequence Organization22
- Ch. 12 - The Genetic Code and Transcription36
- Ch. 13 - Translation and Proteins27
- Ch. 14 - Gene Mutation, DNA Repair, and Transposition34
- Ch. 15 - Regulation of Gene Expression in Bacteria22
- Ch. 16 - Regulation of Gene Expression in Eukaryotes37
- Ch. 17 - Recombinant DNA Technology27
- Ch. 18 - Genomics, Bioinformatics, and Proteomics30
- Ch. 19 - The Genetics of Cancer21
- Ch. 20 - Quantitative Genetics and Multifactorial Traits37
- Ch. 21 - Population and Evolutionary Genetics45
Chapter 10, Problem 16
Define and indicate the significance of
(a) Okazaki fragments,
(b) DNA ligase, and
(c) primer RNA during DNA replication.
Verified step by step guidance1
Start by defining Okazaki fragments: these are short sequences of DNA nucleotides synthesized discontinuously on the lagging strand during DNA replication. Explain their significance as they allow the lagging strand to be replicated in small segments because DNA polymerase can only synthesize DNA in the 5' to 3' direction.
Next, define DNA ligase: an enzyme that joins Okazaki fragments together by forming phosphodiester bonds between adjacent nucleotides. Emphasize its significance in sealing the gaps between Okazaki fragments to create a continuous DNA strand on the lagging strand.
Then, define primer RNA (or RNA primer): a short strand of RNA nucleotides synthesized by primase that provides a starting point for DNA polymerase to begin DNA synthesis. Highlight its importance because DNA polymerase cannot initiate synthesis without a primer.
Explain how these components work together during DNA replication: RNA primers initiate synthesis, Okazaki fragments are formed on the lagging strand, and DNA ligase joins these fragments to ensure the DNA strand is complete and continuous.
Summarize the overall significance of these elements in ensuring accurate and efficient replication of the lagging strand, which is essential for maintaining genetic information during cell division.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Okazaki Fragments
Okazaki fragments are short DNA segments synthesized discontinuously on the lagging strand during DNA replication. Because DNA polymerase can only synthesize DNA in the 5' to 3' direction, these fragments allow replication to proceed in segments opposite to the replication fork movement. They are later joined to form a continuous strand.
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11:59
Steps to DNA Replication
DNA Ligase
DNA ligase is an enzyme that joins Okazaki fragments by forming phosphodiester bonds between adjacent DNA segments. This sealing process is essential for creating a continuous and stable DNA strand on the lagging strand, ensuring the integrity and completeness of the replicated DNA molecule.
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01:45DNA Proofreading
RNA Primer
An RNA primer is a short strand of RNA synthesized by primase that provides a starting point for DNA polymerase to begin DNA synthesis. It is necessary because DNA polymerase cannot initiate synthesis de novo and requires a free 3'-OH group to add nucleotides during replication.
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Related Practice
Textbook Question
Distinguish between
(a) unidirectional and bidirectional synthesis, and
(b) continuous and discontinuous synthesis of DNA.
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Textbook Question
List the proteins that unwind DNA during in vivo DNA synthesis. How do they function?
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Textbook Question
Outline the current model for DNA synthesis.
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Textbook Question
Why is DNA synthesis expected to be more complex in eukaryotes than in bacteria? How is DNA synthesis similar in the two types of organisms?
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Textbook Question
Several temperature-sensitive mutant strains of E. coli display the following characteristics. Predict what enzyme or function is being affected by each mutation.
Newly synthesized DNA contains many mismatched base pairs.
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