Lecture 16

Question 1

What are the 4 changes made to tRNA

Answer 1

1) a 16 nucleotide sequence at the 5’ end is cleaved baby RNase P
2) a 14 nucleotide intros in the anticodon loop is removed
3) uracil residues at the 3’ end are replaced by a CCA sequence
4) certain bases are modified

Question 2

What does the S refer to in ribosomal units?

Answer 2

• sedimentation rate which is proportional to the size of the macromolecule

Question 3

What does the upstream binding factor do?

Answer 3

Helps establish the pre initiation complex by interacting with the upstream control element

Question 4

what does the pol I binding complex lackthat the pol II doesn’t?

Answer 4

TATAAT boxes

Question 5

TFII is transcription factor for what?

Answer 5

Polymerase II because of the II

Question 6

What does TFIIH do?

Answer 6

1) has helicase activity
2) has kinase activity (trigger for the elongation phase of transcription
3) plays a role in DNA repair

Question 7

What is the TATA box responsible for?

Answer 7

• positioned 20-30 nucleotides upstream of the starting site

Question 8

What would happen if you moved the TATA box further upstream from the original start site?

Answer 8

There would be a new start site proportionally further upstream

Question 9

How long is the average intron?

Answer 9

3500 bp -1.5 million bp

Question 10

How long is the average exon?

Answer 10

150 bp

Question 11

What is a CPG island promoter region?

Answer 11

a region with at least 200 bp, and a GC percentage that is greater than 50% and is associated with the start of some genes.

Question 12

What is DNA bending?

Answer 12

The bending of a DNA strand with the purpose of bringing an enhancer element closer to a far away transcription-initiation region.

Question 13

What do nuclear receptors have in common?

Answer 13

• ligand binding domain which binds to hormone
• DNA binding domain which contains the Zinc Finger Motif
• variable region (activation domain)

Question 14

What is the purpose of the Zinc Finger Motif?

Answer 14

• facilitate binding to a specific DNA sequence

Question 15

What is the purpose of NF-kappaB?

Answer 15

• activation of immune response to bacterial and fungal infection

Question 16

How is NF-kappaB activated?

Answer 16

• inhibitor is phosphorylates and then ubiquinated by E3 ligase then proceeds into the nucleus and induces specific transcription of immune proteins

Question 17

How does cAMP activate its genes?

Answer 17

G-protein coupled receptor causes ATP conversion to cAMP, which then activates Protein Kinase A which enters the nucleus and phosphorylates CREB, which then binds to CRE (cAMP response element) and recruits CBP (acetylates neighboring histones)

Question 18

What are pleotropic abnormalities?

Answer 18

When one gene affects multiple seemingly unrelated phenotypic traits

Question 19

What does a mutation at -20 result in?

Answer 19

Hemophilia B Leyden which has reduced HNF4 binding (hepatocyte Nuclear Factor 4) but normal androgen receptor binding so deficient Factor IX levels persist only until puberty.

Question 20

What does a mutation at -26 result in?

Answer 20

Hemophilia B Brandenburg which has reduced HNF4 binding AND reduced Androgen Receptor Binding so deficient Factor IX levels persist throughout life.

Question 21

What happens in aniridia?

Answer 21

heterozygous mutation of the Pax6 allege resulting in the loss of both iris in the eye.