Lec 2.2 Control of gene expression 2

Question 1

What keeps mRNAs around and confers stability?

Answer 1

poly A tail

Question 2

What acts a timer to degrade the mRNA?

Answer 2

shortening of the poly A tail

Question 3

What does the 5’Cap do?

Answer 3

Protects the mRNA from degradation.

Question 4

What are the two pathways when the poly-a tail is greatly shortened?

Answer 4

1. 5’ cap is destroyed and thus degradation of the mRNA from 5’ end. 2. degradation from the 3’ end through the poly A tail

Question 5

What does Ferritin mRNA do?

Answer 5

Makes protein to store iron

Question 6

What does tfR (Transferrin-Receptor) mRNA do?

Answer 6

Brings iron into cell

Question 7

Where is excess iron mainly stored?

Answer 7

liver lungs pancreas

Question 8

What does the cell do during iron starvation?

Answer 8

Dont need iron. Decrease Ferritin mRNA, Increase TfR (transferrin receptor) mRNA

Question 9

what does the cell do during iron excess?

Answer 9

Store excess iron. Increase Ferritin mRNA. Decrease TfR (transferrin receptor) mRNA

Question 10

What are IREs and IRP used for?

Answer 10

Used in a system to control TfR mRNA and Ferritin mRNA

Question 11

What are IREs?

Answer 11

Iron Responsive Elements. Recognition sizte on mRNA for binding

Question 12

What is IRP?

Answer 12

Iron responsive regulatory protein. Proteins that bind to mRNA.

Question 13

What happens if IRP binds to IRE at 5’ ferritin mRNA?

Answer 13

No Ferritin.

Question 14

What happens if IRP binds to IRE at 3’ TfR mRNA?

Answer 14

TfR made

Question 15

What happens if IRP DOESNT bind to IRE at 5’ ferritin mRNA?

Answer 15

Ferritin made.

Question 16

What happens if IRP DOESNT bind to IRE at 3’ TfR mRNA?

Answer 16

No transferrin

Question 17

What happens during cell iron starvation?

Answer 17

Need more iron, IRP binds to Ferritin (no Ferritin made). IRP binds to TfR (TfR made).

Question 18

What happens during Iron excess in the cell?

Answer 18

Need to store. IRP binds to Iron (Ferritin made). No TfR made.

Question 19

What do miRNAs do?

Answer 19

Silence expression of specific mRNA targets.

Question 20

Elevated levels of miRNAs suggest what?

Answer 20

Cardio disease, stroke, can identify cancers

Question 21

Are changes in miRNA expression causative of disease or responsive?

Answer 21

Both

Question 22

What are the 8 ways proteins are regulated by post translational processing and modifications?

Answer 22

1. 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

Question 23

What are molecular chaperones? What do they do?

Answer 23

Are heat shock proteins (Hsp). These proteins get activated to fold proteins back to what they were before they were heat shocked

Question 24

What is a proteasome?

Answer 24

Degrades misfolded proteins

Question 25

What is the structure of a proteasome?

Answer 25

Hollow chamber where proteins are degraded

Question 26

What tells the proteasome what to destroy?

Answer 26

Ubiquitin

Question 27

Genomic imprinting is based on what?

Answer 27

DNA methylation

Question 28

What is genomic imprinting?

Answer 28

Differential expression of genetic material depending on the parent of origin.

Question 29

What is an example of GI?

Answer 29

Epigentics

Question 30

What is epigenetics?

Answer 30

Regulation of expression of gene activity without altering gene structure.

Question 31

What is an example of a GI disease?

Answer 31

PWS. Paternal deletion is lack of gene expression due to GI

Question 32

What is PWS?

Answer 32

Inherits gene deletion from father. No gene expression from mother side.

Question 33

What are some symptoms of PWS?

Answer 33

Hyperphagia (uncontrollable eating). short stature.

Question 34

What is x chromosome inactivation?

Answer 34

How humans deal with extra X's. So equal number of Xs in both females and males. It is random.

Question 35

Describe the RNA control of Ferritin mRNA and TfR mRNA under iron excess.

Answer 35

Need to store. IRP binds to Iron (Ferritin made). No TfR made.

Question 36

Describe genomic imprinting and how it can lead to a disease state.

Answer 36

Differential expression of genetic material depending on the parent of origin. Could cause lack of gene expression.