1. Agenda 3/16 Eukaryotic Control Introduction and Reading
Lactase Gene Regulation Click and Learn
Eukaryotic Control Notes
Homework
1. Agouti Mice Ted Talk
2. Eukaryotic Control Table
Turn in: Video notes, POGIL

2. Eukaryotes vs. Prokaryotes
Eukaryotes have a lot more genes
Chromatin is wrapped around histones in eukaryotes (more obstacles to access DNA)
More regulatory proteins used in eukaryotes than in prokaryotes

3. Why do eukaryotes need gene expression control?
All cells in our body have the exact same DNA
Differences between the cells come from differential gene expression
Some genes are turned off in some cells, other genes are turned on
Gene expression patterns are regulated at many different levels

4. Levels of Gene Expression Control in Eukaryotes
1. Pre-transcriptional
Methylation
Acetylation
Transcription Factors
2. Post-transcriptional
Alternative splicing
3. Post-translational
Ubiquitination

5. DNA Organization in Eukaryotes
In order for transcription to occur, enzymes like RNA polymerase must be able to access the DNA
Allowing or restricting that access is one way we can control gene expression
Double helix DNA is wrapped around histone proteins

6. Epigenetics (Pre-transcriptional)
Epigenetics (Above the genome) is the process of gene regulation that occurs without changing the underlying sequence of DNA
Chemical groups can bind to DNA and make the DNA more likely or less likely to be transcribed (turn genes on or off)
Two types
1. Acetylation
2. Methylation

7. Acetylation (pre-transcriptional)
The amino acid lysine in the histone proteins can bind the acetyl groups
When acetylation occurs at a lysine, it decreases the affinity of the histone proteins for DNA
Meaning the DNA binds less tightly to the histone proteins
This makes the DNA more accessible for transcription
‘Gene turned on’ or ‘gene activated’

8. Methylation (pre-transcriptional)
A methyl group can bind the cytosines that are followed by guanine in DNA
Methylation makes DNA bind more tightly to the histone proteins
DNA is less accessible
‘gene turned off’ or ‘gene deactivated’

10. Epigenetics and the environment
Scientists have found that certain environmental factors affect your epigenome
For example, cigarette smoke and stress can create ‘bad epigenetic marks’
Exercise and healthy eating can create ‘good epigenetic marks’
There is some evidence that these epigenetic markers are passed down through generations
Meaning, that the choices your grandparents made affect the expression of your genes

11. Transcription Factors (pre-transcriptional)
Transcription factors are proteins that bind to or near the promoter region and help RNA polymerase attach (making transcription more likely)
Inducer regions are sequences of DNA that transcription factors may attach to
Enhancer regions can by 1000s of nucleotides away but can also bind TFs which can loop back to promoter region and promote transcription

12. Alternative Splicing (post-transcriptional)
Once the immature mRNA is made, it can be processed in different ways which will give rise to different proteins
This process is highly regulated and organized by lots of different proteins
In one cell, proteins may include an exon in the mRNA but in a different cell it may be spliced out with the introns

13. Ubiquitination (Post-translational)
Ubiquitin is a protein that can ‘tag’ other proteins for destruction
Proteins that are tagged with ubiquitin (ubiquitinated) will be degraded in the proteasome