Essential Idea:
Genetic information in DNA can be accurately copied and
can be translated to make the proteins needed by the cell
Understandings:
- The replication of DNA is semi-conservative and depends on complementary base pairing
- Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds
- DNA polymerase links nucleotides together to form a new strand, using the pre-existing strand as a template
- Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase
- Translation is the synthesis of polypeptides on ribosomes
- The amino acid 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
Applications:
- Use of Taq DNA polymerase to produce multiple copies of DNA rapidly by the polymerase chain reaction (PCR)
- Production of human insulin in bacteria as an example of the universality of the genetic code allowing for gene transfer between species
Skills:
- Use a table of the genetic code to deduce which codon(s) correspond to which amino acid
- Analysis of Meselson and Stahl’s results to obtain support for the theory of semi-conservative replication of DNA
- Use a table of mRNA codons and their corresponding amino acids to deduce the sequence of amino acids coded by a short mRNA strand of known base sequence
- Deducing the DNA base sequence for the mRNA strand