2.7 DNA Replication, Transcription and Translation

2.7 DNA Replication, Transcription and Translation

1. DNA Replication

   • Nature of Science
     • Evidence for scientific theories
       • Meselson and Stahl
         • Semi-conservative replication of DNA
           • Complementary base pairing
           • Helicase
             • Unwinds the double helix and separates the two strands by breaking H bonds
           • DNA Polymerase
             • Links nucleotides together to form a new strand, using pre-existing strand as a template
   • Polymerase chain reaction (PCR)
     • Use of Taq DNA polymerase to produce multiple copies of DNA rapidly

2. Transcription

   • Synthesis of mRNA copied from the DNA base sequences by RNA polymerase

3. Translation

   • Synthesis of polypetides on ribosomes
     • The amino acids sequence of polypeptides is determined by mRNA according to the genetic code
       • Codons of three bases on mRNA correspond to one amino acid in a polypeptide
         • Translation depends on complementary base pairing between codons on mRNA and anticodons on tRNA
         • Use a table of the genetic code to deduce which codon corresponds to which amino acid
           • Deducing the DNA base sequence for the mRNA strand

4. Aim 8

   • Ethical implications in altering the genome of an organism in order to produce proteins for medical use in humans
     • Production of human insulin in bacteria as an example of the universal versatility of the genetic code allowing gene transfer between species