Lecture 02

• What type of replication is DNA replication?

  Semi-conservative replication

  
• What does DNA polymerase require for replication?

  It requires dNTPs and a primer

  
• What is the nature of the primer in DNA replication?

  It is an RNA primer

  
• What are Okazaki fragments?

  Short DNA segments on the lagging strand

  
• What is the role of different enzymes in DNA replication?

  They facilitate various steps of replication

  
• What is the overall process of DNA replication?

  It involves unwinding, synthesising, and proofreading

  
• What keeps the DNA strands together during replication?

  Strong hydrogen bonds
• How does DNA polymerase add nucleotides?

  It adds them to the growing DNA strand

  
• What bond does DNA polymerase form during replication?

  A phosphodiester bond

  
• What is released when dNTPs are added to the DNA strand?

  Two phosphates as pyrophosphate
• In which direction does DNA replication occur?

  From 5’ to 3’ direction

  
• What is the role of RNA primers in DNA replication?

  They initiate DNA synthesis

  
• Why are Okazaki fragments necessary?

  Because DNA strands are antiparallel

  
• How many origins of replication do eukaryotic chromosomes have?

  Multiple origins of replication
• How many origins of replication do prokaryotic chromosomes typically have?

  Typically a single origin of replication
• What is the appearance of each origin of replication?

  It appears as a bubble along the chromosome

  
• What are the three rules of DNA polymerase?

  Single-stranded DNA, adds to existing chain, 5' to 3'

  
• What must happen to RNA primers after DNA synthesis?

  They need to be removed
• Why can DNA polymerase only synthesise DNA in one direction?

  Because DNA strands are antiparallel

  
• What is the significance of bidirectional replication?

  It allows faster replication of DNA

  
• What is the function of primase in prokaryotes?

  Synthesises RNA primer
• What is the function of DNA ligase?

  Joins gaps in DNA backbone
• What is the role of DNA polymerase III in prokaryotes?

  Responsible for replication

  
• What is the role of DNA polymerase I in prokaryotes?

  Responsible for repair and removing primers

  
• What are the main DNA polymerases involved in eukaryotic chromosome replication?

  DNA polymerase α, δ, ε

  
• What does DNA polymerase α do?

  Initiates DNA replication by synthesising primer

  
• What does DNA polymerase δ do?

  Synthesises the lagging strand

  
• What does DNA polymerase ε do?

  Primarily synthesises the leading strand

  
• How do prokaryotic cells divide?

  By binary fission

  
• What type of cells are higher animals and plants?

  Diploid cells
• What are telomeres?

  Repeat sequences at the end of chromosomes
• What is the function of telomerase?

  Completes ends of chromosomes using RNA template

  
• What is the role of DNA helicase?

  Unwinds the double helix and separates strands

  
• What energy source does helicase require?

  ATP is needed for movement and bond breaking
• What do single-strand binding proteins do?

  Stabilise and straighten single-stranded DNA

  
• How does DNA polymerase link nucleotides?

  Using the pre-existing strand as a template

  
• What type of reaction is the polymerisation reaction by DNA polymerase?

  A condensation reaction

  
• In which direction does DNA polymerase always move?

  In a 5’ to 3’ direction

  
• What does DNA polymerase catalyse between sugars and phosphate groups?

  Covalent phosphodiester bonds

  
• How often do errors occur during DNA replication?

  About 1 mistake per 10^5 nucleotides