DNA Replication in Prokaryotes Lecture Notes PDF
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Uploaded by SweetNitrogen
David P. Clark
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Summary
These lecture notes detail DNA replication in prokaryotes. They cover topics including the need for replication, processes occurring at the replication fork, strand separation, DNA polymerases, and the completion of the lagging strand. This document contains information about DNA replication mechanisms, enzymes, and processes.
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DNA Replication; Prokaryotic Chapter no. 5 (Cell division and DNA Replication) Book: Molecular Biology By David P. Clark DNA Replication Cell division and DNA Replication: Need of Replication Replication in Prokaryotes R...
DNA Replication; Prokaryotic Chapter no. 5 (Cell division and DNA Replication) Book: Molecular Biology By David P. Clark DNA Replication Cell division and DNA Replication: Need of Replication Replication in Prokaryotes Replication in Eukaryotes Unicellular and Multicellular organism’s reproduction A-sexual and Sexual reproduction Transfer of Genetic information during sexual reproduction Horizontal transfer & Vertical transfer DNA Replication Is a Two-Stage Process Occurring at the Replication Fork Separation of Parental strands Building two new strands Complementary base pairing and Template Strand Replication Fork: Separated strands + Assemblage of proteins – Replisome DNA Replication Strand Separation: Helicase – Disrupt H-bonds DnaB – E. coli DNA helicase SSBPs Single Stranded Region length DNA polymerases Introduction Properties: 1. 5’ to 3’ polymerization 2. Leading strand (Continuous) 3. Lagging strand (Discontinuous) 4. RNA primer (RNA polymerase) A. Leading Strand – One primer B. Lagging strand – Multiple premiers DNA Replication DNA or RNA replication – 5’ to 3’ direction New nucleotides – 3’ end Precursors: Deoxyribonucleoside 5’- triphosphates (deoxy-NTPs) 1. dATP 2. dGTP 3. dCTP 4. dTTP Phosphate groups – α, β, γ Polymerization – α and β bonds break – Energy β and γ phosphates – pyrophosphate Bond between α phosphate and 3’-OH DNA Replication Precursors for DNA synthesis: 1. Ribonucleotides to Deoxyribonucleotides Conversion 2. Diphosphate nucleotides to Triphosphate nucleotides Conversation 3. Different Pathway for dUDP: 4. Pathway for dUDP: A. dUDP to dUMP (Removal of phosphate) B. dUMP to dTMP (Enzyme - thymidylate synthetase) C. dTMP to dTTP (2 phosphates are added) Methyl Group Carrier – Tetrahydrofolate (THF) Co-factor Dihydrofolate reductase – DHF to THF Trimethoprim Methotrexate DNA Replication DNA Polymerase Elongates DNA Strands: DNA Polymerase III Components: Sliding Clamp – Semicircular subunits (DnaN) Accessary Proteins – Clamp loader HolA, B, C, D and γ subunits Core Enzyme DnaE (α) DnaQ (ε) HolE (θ) 2 assemblies –tau (τ) subunit DNA Replication DNA Polymerase Elongates DNA Strands: Kinetic Proofreading ability Mismatch – Structure DnaQ (3’ exonuclease activity) Replication Fork: Definition Components Leading Strand Lagging Strand DNA Replication Primosome: Leading and Lagging Strand PriA – Displace – SSBs – DnaG (Primase) – Primer Loading and Re-loading of Sliding Clamp – Lagging strand 2 DNA polymerase III assemblies – 2 Sliding clamps – 1 Sliding clamp loader DNA Replication Completion of Lagging Strand: Lagging Strand – Okazaki Fragments – RNA primers Enzymes DNA polymerase I DNA ligase Ribonuclease H (RNaseH) Nick Repair – DNA Pol I Nick Translation Discovery of DNA Pol I, II & III
