Lec 2.2 Control of gene expression 2 Flashcards
What keeps mRNAs around and confers stability?
poly A tail
What acts a timer to degrade the mRNA?
shortening of the poly A tail
What does the 5’Cap do?
Protects the mRNA from degradation.
What are the two pathways when the poly-a tail is greatly shortened?
- 5’ cap is destroyed and thus degradation of the mRNA from 5’ end. 2. degradation from the 3’ end through the poly A tail
What does Ferritin mRNA do?
Makes protein to store iron
What does tfR (Transferrin-Receptor) mRNA do?
Brings iron into cell
Where is excess iron mainly stored?
liver lungs pancreas
What does the cell do during iron starvation?
Dont need iron. Decrease Ferritin mRNA, Increase TfR (transferrin receptor) mRNA
what does the cell do during iron excess?
Store excess iron. Increase Ferritin mRNA. Decrease TfR (transferrin receptor) mRNA
What are IREs and IRP used for?
Used in a system to control TfR mRNA and Ferritin mRNA
What are IREs?
Iron Responsive Elements. Recognition sizte on mRNA for binding
What is IRP?
Iron responsive regulatory protein. Proteins that bind to mRNA.
What happens if IRP binds to IRE at 5’ ferritin mRNA?
No Ferritin.
What happens if IRP binds to IRE at 3’ TfR mRNA?
TfR made
What happens if IRP DOESNT bind to IRE at 5’ ferritin mRNA?
Ferritin made.
What happens if IRP DOESNT bind to IRE at 3’ TfR mRNA?
No transferrin
What happens during cell iron starvation?
Need more iron, IRP binds to Ferritin (no Ferritin made). IRP binds to TfR (TfR made).
What happens during Iron excess in the cell?
Need to store. IRP binds to Iron (Ferritin made). No TfR made.
What do miRNAs do?
Silence expression of specific mRNA targets.
Elevated levels of miRNAs suggest what?
Cardio disease, stroke, can identify cancers
Are changes in miRNA expression causative of disease or responsive?
Both
What are the 8 ways proteins are regulated by post translational processing and modifications?
- Post translational modifications. 2. Must fold to 3-d conformations. 3. Molecular chaperones. 4. Bind co-factors.5. Modified by protein Kinases. 6. Glycosylated. 7. Bind to other protein subunits or protein partners. 8. Modifying enzymes act on protein
What are molecular chaperones? What do they do?
Are heat shock proteins (Hsp). These proteins get activated to fold proteins back to what they were before they were heat shocked
What is a proteasome?
Degrades misfolded proteins
What is the structure of a proteasome?
Hollow chamber where proteins are degraded
What tells the proteasome what to destroy?
Ubiquitin
Genomic imprinting is based on what?
DNA methylation
What is genomic imprinting?
Differential expression of genetic material depending on the parent of origin.
What is an example of GI?
Epigentics
What is epigenetics?
Regulation of expression of gene activity without altering gene structure.
What is an example of a GI disease?
PWS. Paternal deletion is lack of gene expression due to GI
What is PWS?
Inherits gene deletion from father. No gene expression from mother side.
What are some symptoms of PWS?
Hyperphagia (uncontrollable eating). short stature.
What is x chromosome inactivation?
How humans deal with extra X’s. So equal number of Xs in both females and males. It is random.
Describe the RNA control of Ferritin mRNA and TfR mRNA under iron excess.
Need to store. IRP binds to Iron (Ferritin made). No TfR made.
Describe genomic imprinting and how it can lead to a disease state.
Differential expression of genetic material depending on the parent of origin. Could cause lack of gene expression.
