Topic 7.2: Transcription and Gene Expression

Essential Idea:  Information stored as a code in DNA is copied onto mRNA.
At SHS, Topic 7.2 is taught in the following class unit(s):

Statements & Objectives:

7.2.U1  Gene expression is regulated by proteins that bind to specific base sequences in DNA.
  • Define gene expression.
  • State two reasons why gene expression must be regulated.
  • Outline the environmental regulation of the breakdown of lactose in E. coli.
  • Outline the role of enhancers, silencers and promoter-proximal elements in regulation of gene expression.
7.2.U2  The environment of a cell and of an organism has an impact on gene expression.
  • Describe the use of twin studies to measure the impact of environment on gene expression.
  • Outline two examples of environmental influence on gene expression.
7.2.U3  Nucleosomes help to regulate transcription in eukaryotes.
  • Outline the effect of methylation of nucleosome tails on rates of gene expression.
  • Outline the effect of acetylation of nucleosome tails on rates of gene expression.
7.2.U4  Transcription occurs in a 5’ to 3’ direction.
  • Describe the initiation of transcription, including the role of the promoter, transcription factors, the TATA box and RNA polymerase. 
  • Describe elongation of transcription, including the role of nucleotide triphosphates and the direction of transcription. 
  • Describe termination of transcription, including the role of the terminator.
 7.2.U5  Eukaryotic cells modify mRNA after transcription.
  • List two major differences in gene expression between prokaryotic cells and eukaryotic cells.
  • Describe the three post-transcriptional modifications of pre-mRNA in eukaryotes.
7.2.U6  Splicing of mRNA increases the number of different proteins an organism can produce.
  • Describe the process of alternative RNA splicing.
  • Outline an example of alternative splicing the results in different protein products.
7.2.A1  The promoter as an example of non-coding DNA with a function.
  • Outline the role of promoter DNA.
7.2.S1  Analysis of changes in the DNA methylation patterns.
  • State the effect of DNA methylation on gene expression.
  • Compare methylation patterns in twins using superimposed images of dyed chromosomes.
7.2.NOS  Looking for patterns, trends and discrepancies- there is mounting evidence that the environment can trigger heritable changes in epigenetic factors.
  • Define epigenetic and epigenome.
  • List types of epigenetic tags.
  • Discuss the role of reprogramming and imprinting on epigenetic factors.

In the News:
"When we try to pick out anything by itself, we find it hitched to everything else in the Universe." 
 John Muir,   1911