DNA replication

• What is the fundamental biological process that ensures the accurate transmission of genetic information?

  DNA replication
• What does the term "semi-conservative" mean in the context of DNA replication?

  Each newly synthesized DNA molecule contains one original strand and one newly synthesized strand
• Why is the semi-conservative nature of DNA replication important?

  It maintains genetic stability across generations
• What pairs with adenine (A) in DNA replication?

  Thymine (T)
• What pairs with guanine (G) in DNA replication?

  Cytosine (C)
• If a section of the template strand reads ATCG, what will the newly synthesized complementary strand be?

  TAGC
• What is the role of helicase in DNA replication?

  It unwinds the double helix by breaking hydrogen bonds between base pairs
• What structure does helicase create during DNA replication?

  A replication fork
• What is the function of DNA gyrase (topoisomerase) during DNA replication?

  It relieves tension caused by unwinding the DNA
• What do single strand binding proteins (SSBPs) do during DNA replication?

  They prevent single strands from re-annealing and protect them from degradation
• What must be synthesized before DNA synthesis can begin?

  A short RNA primer
• Which enzyme synthesizes the RNA primer?

  DNA primase
• What is a common mistake students make regarding DNA primase and DNA polymerase?

  Confusing primase, which creates the RNA primer, with polymerase, which extends the primer
• In which direction does DNA synthesis occur?

  5' to 3' direction
• What is the difference between the leading strand and the lagging strand during DNA synthesis?

  The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments
• What are the short segments synthesized on the lagging strand called?

  Okazaki fragments
• What initiates each Okazaki fragment on the lagging strand?

  An RNA primer synthesized by primase
• What are the two main types of DNA polymerases in prokaryotes?

  DNA Polymerase III and DNA Polymerase I
• What is the primary role of DNA Polymerase III?

  It is responsible for DNA synthesis by adding nucleotides to the growing DNA strand
• What is the role of DNA Polymerase I in DNA replication?

  It removes RNA primers and replaces them with DNA nucleotides
• How can you remember the roles of DNA Polymerase III and I?

  Polymerase III does the main synthesis, while Polymerase I does the "clean-up" work
• What is a key difference between prokaryotic and eukaryotic DNA replication?

  Prokaryotes have a single origin of replication, while eukaryotes have multiple origins
• Why do eukaryotic chromosomes require special mechanisms for replication?

  Because they are linear and need to replicate the ends (telomeres)
• What was the purpose of the Meselson-Stahl experiment?

  To demonstrate the semi-conservative nature of DNA replication
• What method did Meselson and Stahl use to analyze DNA samples?

  Density gradient centrifugation
• What were the results after one generation in the Meselson-Stahl experiment?

  All DNA molecules had intermediate density (one heavy strand, one light strand)
• What were the results after two generations in the Meselson-Stahl experiment?

  Half the DNA molecules had intermediate density, and half had light density
• How do the results of the Meselson-Stahl experiment support the semi-conservative model of DNA replication?

  The results showed that DNA replication produces molecules with one original and one new strand
• What is the Polymerase Chain Reaction (PCR) based on?

  The understanding of DNA replication
• What enzyme is used in PCR to produce multiple copies of a specific DNA sequence?

  Taq DNA polymerase
• What are the three main steps of the PCR process?

  Denaturation, annealing, and extension
• What happens during the denaturation step of PCR?

  The DNA is heated to separate the strands
• What occurs during the annealing step of PCR?

  Primers bind to specific sequences on the single-stranded DNA
• What happens during the extension step of PCR?

  Taq polymerase synthesizes new DNA strands
• How does PCR increase the amount of target DNA?

  By repeating the three main steps for multiple cycles
• What is one application of PCR?

  Genetic testing for diseases
• Name another application of PCR.

  Forensic analysis of DNA evidence
• What is a third application of PCR?

  Detection of bacterial or viral infections
• What is a fourth application of PCR?

  Cloning of genes for research purposes
• What are the key concepts of DNA replication?

  • Semi-conservative process
  • Complementary base pairing
  • Role of helicase and DNA gyrase
  • Function of single strand binding proteins
  • Primer synthesis by DNA primase
  • Leading and lagging strand synthesis
  • Role of DNA polymerases
  • Differences between prokaryotic and eukaryotic replication
  • Meselson-Stahl experiment
  • Applications of PCR