Download Gene Regulation Notes

IB BIOLOGY
GENE REGULATION
I. In prokaryotes
A. occurs in response to the environment
II. In eukaryotes
A. occurs in response to the environment and for cell specialization
B. when does regulation occur?
1. transcription-which genes get transcribed and when?
2. mRNA processing-addition of a 5’ cap, 3’ poly-A tail and removal of introns
a. RNA will not be transported out of the nucleus if it is not processed; therefore, it
will not be translated
b. exon shuffling-the exons in a single gene can be spliced/combined in various ways
and thus produce different protein products
i. in mammals the calcitonin gene produces a hormone in one type of cell and a
neurotransmitter in another type of cell
ii. in Drosophila, a specific RNA called the sex-lethal RNA can be spliced to produce
an mRNA that produces a functional polypeptide or one with a stop codon early
on that translates into a short, non-functional polypeptide
Figure 1. Example of exon shuffling.
http://www.emunix.emich.edu/~rwinning/genetics/eureg2.htm
In cell 1, exons 1, 2, and 4 would be used in the mRNA:
In cell 2 on the other hand, exons 1, 3, and 4 would be used:
3. mRNa lifetime
a
4. translation
III. Feb. 9, 2011: http://www.urmc.rochester.edu/news/story/index.cfm?id=3113
Scientists Discover Gene Regulation Mechanism Unique to Primates
A. involves Alu elements (repetitive DNA elements that spread throughout the genome as
primates evolved)
B. Alu elements regulate protein productions along with long non-coding RNA’s (lncRNAs)
1. together, they regulate mRNA’s and prevent too much protein production
2. trigger a process called Staufen 1-mediated mRNA decay
a. SMD destroys mRNA’s after a certain amount of protein has been produced
i. prevent too much of any particular protein
a. too much protein could disrupt the cell and cause disease
3. the lncRNA’s and Alu elements cause a protein called Staufen-1 to bind to mRNA’s
4. once the mRNA’s have been translated, Staufen-1 works with another protein called
UPF1 to initiate the degradation/decay of the mRNA
References:
1.
2.
3.
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6.
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Promoter.html
http://www.emunix.emich.edu/~rwinning/genetics/eureg.htm
http://www.emunix.emich.edu/~rwinning/genetics/develop.htm
http://www.urmc.rochester.edu/news/story/index.cfm?id=3113
http://morrislab.med.utoronto.ca/papers/BlencowePacSympBioc09.pdf
http://www.gene-quantification.com/nature-reviews-microrna-2.pdf
7. http://www.science20.com/curious_cub/gene_regulation_and_difference_between_huma
n_beings_and_chimpanzees-83981
8. http://www.medicalnewstoday.com/releases/226741.php
9. http://www.physorg.com/news/2011-08-periods-gene-evolution-vertebrate-animals.html
10.http://www.nature.com/scitable/topicpage/obesity-epigenetics-and-gene-regulation-927
11.Bacterial gene regulation: http://pathmicro.med.sc.edu/mayer/geneticreg.htm
12.Bacterial gene regulation:
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/L/LacOperon.html
13. A graphic to visualize gene expression:
http://www.mhhe.com/biosci/genbio/biolink/j_explorations/ch16expl.htm
14.