DNA application and the genetic code

• What is the specification reference for DNA replication and the genetic code?

  1. 1.3
• What are the learning outcomes for this topic?

  Knowledge, understanding, and application of genetic code
• Why do cells divide?

  To reproduce, grow, or repair tissues
• What do the two daughter cells produced during cell division contain?

  DNA with identical base sequences
• What happens to the DNA double helix when a cell prepares to divide?

  The two strands unwind and separate
• What is the process called when DNA strands serve as templates for new molecules?

  DNA replication
• What ensures that the two new DNA strands are identical to the original?

  Complementary base pairing
• What must happen for DNA to replicate?

  The double helix must unwind and separate
• What breaks the hydrogen bonds during DNA replication?

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

  It unwinds and separates the DNA strands
• What type of bonds are formed between nucleotides during DNA replication?

  Phosphodiester bonds
• What happens during the unzipping process of DNA replication?

  Free nucleotides pair with exposed bases
• What is semi-conservative replication?

  Each new DNA molecule has one old and one new strand
• How does DNA polymerase function during replication?

  It catalyzes the formation of phosphodiester bonds
• In which direction does DNA polymerase move along the template strand?

  From 3′ to 5′ direction
• What is the leading strand in DNA replication?

  The strand replicated continuously from the 3′ end
• What is the lagging strand in DNA replication?

  The strand replicated in sections called Okazaki fragments
• What are Okazaki fragments?

  Sections of DNA produced on the lagging strand
• What causes replication errors in DNA?

  Incorrect base pairing during replication
• What is a mutation?

  A change in the DNA base sequence
• What is the role of DNA in organisms?

  It carries genetic information
• What does DNA code for?

  A sequence of amino acids in proteins
• What is a gene?

  A section of DNA coding for a protein
• What is the genetic code described as?

  Universal among all organisms
• How many different codons are possible with four bases?

  64 different codons
• What is a start codon?

  A codon that signals the start of protein synthesis
• What do stop codons do?

  They signal the end of the protein coding sequence
• What does it mean for the genetic code to be degenerate?

  Many amino acids can be coded by multiple codons
• What ensures that the DNA sequence is non-overlapping?

  Codons are read in units of three bases
• How many different amino acids occur in biological proteins?

  20 different amino acids
• What is the significance of having a single start codon?

  It ensures triplets are read in units of three
• What is the relationship between DNA and proteins?

  DNA provides instructions to synthesize proteins
• What is the role of enzymes in DNA replication?

  They act as catalysts in biochemical reactions
• Why does DNA polymerase not join Okazaki fragments?

  A different enzyme, DNA ligase, is used
• What are the steps of DNA replication?

  1. DNA double helix unwinds
  2. DNA strands separate
  3. DNA helicase breaks hydrogen bonds
  4. Free nucleotides pair with exposed bases
  5. DNA polymerase forms phosphodiester bonds
  6. Two new DNA molecules are formed
• What are the differences between continuous and discontinuous replication?

  • Continuous replication occurs on the leading strand
  • Discontinuous replication occurs on the lagging strand
  • Leading strand is synthesized continuously
  • Lagging strand is synthesized in Okazaki fragments
• What are the characteristics of the genetic code?

  • Universal across all organisms
  • Composed of triplet codons
  • Degenerate, with multiple codons for amino acids
  • Non-overlapping, read in units of three bases
• What are the implications of mutations in DNA replication?

  • Mutations can lead to changes in protein synthesis
  • May result in altered traits or diseases
  • Can occur naturally and spontaneously
  • Errors in base pairing during replication
• What is the role of DNA ligase in DNA replication?

  • Joins Okazaki fragments on the lagging strand
  • Completes the synthesis of the lagging strand
  • Ensures continuous DNA molecule formation
• What is the significance of the triplet code in DNA?

  • Each triplet (codon) codes for an amino acid
  • Determines the sequence of amino acids in proteins
  • Essential for accurate protein synthesis