Topic 2.7:  DNA Replication, Transcription and Translation

Essential Idea:  Genetic information in DNA can be accurately copied and can be translated to make the proteins needed by the cell.
At SHS, Topic 2.7 is taught in the following class unit(s):

Statements & Objectives:

2.7.U1  The replication of DNA is semi-conservative and depends on complimentary base pairing.
  • Describe the meaning of “semi-conservative” in relation to DNA replication.
  • Explain the role of complementary base pairing in DNA replication.​
2.7.U2  Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds.
  • State why DNA strands must be separated prior to replication.
  • Outline two functions of helicase.
  • State the role of the origin of replication in DNA replication.
  • Contrast the number of origins in prokaryotic cells to the number in eukaryotic cells.​
2.7.U3  DNA polymerase links nucleotides together to form a new strand, using a pre-existing strand as a template.
  • Describe the movement of DNA polymerase along the DNA template strand.
  • Describe the action of DNA polymerase III in pairing nucleotides during DNA replication.​
2.7.U4  Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase.
  • Define transcription.
  • Outline the process of transcription, including the role of RNA polymerase and complementary base pairing. 
  • Identify the sense and antisense strands of DNA given a diagram of translation.​
2.7.U5  Translation is the synthesis of polypeptides on ribosomes.
  • Define translation.
  • State the location of translation in the cell.​
2.7.U6  The amino acid sequence of polypeptides is determined by mRNA according to the genetic code.
  • Outline the role of messenger RNA in translation.
2.7.U7  Codons of three bases on mRNA correspond to one amino acid in a polypeptide.
  • Define codon, redundant and degenerate as related to the genetic code.
  • Explain how using a 4 letters nucleic acid “language” can code for a “language” of 20 amino acid letters in proteins.
2.7.U8  Translation depends on complimentary base-pairing between codons on mRNA and anti codons on tRNA.
  • Outline the role of complementary base pairing between mRNA and tRNA in translation.
2.7.A1  Use of Taq DNA polymerase to produce multiple copies of DNA rapidly by the polymerase chain reaction (PCR).
  • Outline the process of the PCR.
  • Explain the use of Taq DNA polymerase in the PCR.
2.7.A2  Production of human insulin in bacteria as an example of the universality of the genetic code allowing gene transfer between species.
  • Outline the source and use of pharmaceutical insulin prior to the use of gene transfer technology.
  • Outline the benefits of using gene transfer technology in the production of pharmaceutical insulin.
2.7.S1  Use a table of the genetic code to deduce which codons corresponds to which amino acids.
  • Use a genetic code table to deduce the mRNA codon(s) given the name of an amino acid.
2.7.S2  Analysis of Meselson and Stahl’s results to obtain support for the theory of semi-conservative replication of DNA.
  • Compare dispersive, conservative and semi-conservative replication.
  • Predict experimental results in the Meselson and Stahl experiment if DNA replication was dispersive, conservative or semi-conservative.
2.7.S3  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.
  • Use a genetic code table to determine the amino acid sequence coded for by a given antisense DNA sequence or an mRNA sequence.
2.7.S4  Deducing the DNA base sequence for the mRNA strand.
  • Deduce the antisense DNA base sequence that was transcribed to produce a given mRNA sequence.
2.7.NOS  Obtaining of evidence for scientific theories- Meselson and Stahl obtained evidence for the semi-conservative replication of DNA.
  • Describe the procedure of the Meselson and Stahl experiment.
  • Explain how the Meselson and Stahl experiment demonstrated semi-conservative DNA replication.
"When we try to pick out anything by itself, we find it hitched to everything else in the Universe." 
 John Muir,   1911