Molecular Biology of The Cell, Chapter 5 Part 2 PDF

Chapter 5 DNA Replication, Repair, and Recombination Part 2 Copyright © 2022 W. W. Norton & Company, Inc. DNA Replication Mechanisms Special Proteins Help to Open Up the DNA Double Helix in Front of the Replication Fork A Sliding Ring Holds a Moving DNA Polymerase Onto the DNA The Proteins at a Repl...

Chapter 5 DNA Replication, Repair, and Recombination Part 2 Copyright © 2022 W. W. Norton & Company, Inc. DNA Replication Mechanisms Special Proteins Help to Open Up the DNA Double Helix in Front of the Replication Fork A Sliding Ring Holds a Moving DNA Polymerase Onto the DNA The Proteins at a Replication Fork Cooperate to Form a Replication Machine DNA Replication Is Fundamentally Similar in Eukaryotes and Bacteria A Strand-directed Mismatch Repair System Removes Replication Errors That Remain in the Wake of the Replication Machine The Accidental Incorporation of Ribonucleotides During DNA Replication Is Corrected DNA Topoisomerases Prevent DNA Tangling During Replication DNA Helicase: A special Protein Helps to Open Up the DNA Double Helix in Front of the Replication Fork A Sliding Ring Holds a Moving DNA Polymerase Onto the DNA Sliding clamp The Proteins at a Replication Fork Cooperate to Form a Replication Machining Replication DNA Replication Is Fundamentally Similar in Eukaryotes and Bacteria DNA Replication Is Fundamentally Similar in Eukaryotes and Bacteria Leading strand 11 subunits in eukaryotes 6 in prokaryotes (Hexamer Moves on leading strand In eukaryotes 3 subunits in eukaryotes vs 1 in prokaryotes A Strand-directed Mismatch Repair System Removes Replication Errors That Remain in the Wake of the Replication Machine The Accidental Incorporation of Ribonucleotides During DNA Replication Is Corrected. The concentration of the ribonucleotides in the cell is much higher than deoxy counterparts. DNA Topoisomerases Prevent DNA Tangling During Replication The Initiation and Completion of DNA Replication in Chromosomes DNA Synthesis Begins at Replication Origins Bacterial Chromosomes Typically Have a Single Origin of DNA Replication Eukaryotic Chromosomes Contain Multiple Origins of Replication In Eukaryotes, DNA Replication Takes Place During Only One Part of the Cell Cycle New Nucleosomes Are Assembled Behind the Replication Fork Termination of DNA Replication Occurs Through the Ordered Disassembly of the Replication Fork Telomerase Replicates the Ends of Chromosomes Telomeres Are Packaged Into Specialized Structures That Protect the Ends of Chromosomes Telomere Length Is Regulated by Cells and Organisms DNA Synthesis Begins at Replication Origins Bacterial Chromosomes Typically Have a Single Origin of DNA Replication Eukaryotic Chromosomes Contain Multiple Origins of Replication The initiator protein bind to specific DNA sequences at the replication origin and destabilize the double helix. The replication origin is rich in AT sequence. In Eukaryotes, DNA Replication Takes Place During Only One Part of the Cell Cycle Properties of the ORC Ensure That Each Region of the DNA Is Replicated Once and Only Once in Each S Phase New Nucleosomes Are Assembled Behind the Replication Fork Released completely Remain associated to the fork -Histones disassemble in front of replication fork are facilitated by chaperone FACT. -Histone chaperones (NAP1 and CAF1) restore the full complement of histones Telomeres Are Packaged Into Specialized Structures That Protect the Ends of Chromosomes - Telomerase is composed of multiple protein subunits and RNA (Ribonucleoprotein). - RNA provides the template for the new telomere. Telomerase Replicates the Ends of Chromosomes As the lagging-strand replication machinery reaches the end of the chromosome, at some point, primase no longer has sufficient space to synthesize a new RNA primer. This results replication in incomplete and a short ssDNA region at the 3’ end of the lagging-strand DNA product. When this DNA product is replicated in the next round, one of the two products will be shortened and will lack the region that was not fully copied in the previous round of replication. Telomerase Replicates the Ends of Chromosomes The Initiation and Completion of DNA Replication in Chromosomes Termination of DNA Replication Occurs Through the Ordered Disassembly of the Replication Fork