Lecture 16 Flashcards
What are the 4 changes made to tRNA
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
What does the S refer to in ribosomal units?
- sedimentation rate which is proportional to the size of the macromolecule
What does the upstream binding factor do?
Helps establish the pre initiation complex by interacting with the upstream control element
what does the pol I binding complex lackthat the pol II doesn’t?
TATAAT boxes
TFII is transcription factor for what?
Polymerase II because of the II
What does TFIIH do?
1) has helicase activity
2) has kinase activity (trigger for the elongation phase of transcription
3) plays a role in DNA repair
What is the TATA box responsible for?
- positioned 20-30 nucleotides upstream of the starting site
What would happen if you moved the TATA box further upstream from the original start site?
There would be a new start site proportionally further upstream
How long is the average intron?
3500 bp -1.5 million bp
How long is the average exon?
150 bp
What is a CPG island promoter region?
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.
What is DNA bending?
The bending of a DNA strand with the purpose of bringing an enhancer element closer to a far away transcription-initiation region.
What do nuclear receptors have in common?
- ligand binding domain which binds to hormone
- DNA binding domain which contains the Zinc Finger Motif
- variable region (activation domain)
What is the purpose of the Zinc Finger Motif?
- facilitate binding to a specific DNA sequence
What is the purpose of NF-kappaB?
- activation of immune response to bacterial and fungal infection
How is NF-kappaB activated?
- inhibitor is phosphorylates and then ubiquinated by E3 ligase then proceeds into the nucleus and induces specific transcription of immune proteins
How does cAMP activate its genes?
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)
What are pleotropic abnormalities?
When one gene affects multiple seemingly unrelated phenotypic traits
What does a mutation at -20 result in?
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.
What does a mutation at -26 result in?
Hemophilia B Brandenburg which has reduced HNF4 binding AND reduced Androgen Receptor Binding so deficient Factor IX levels persist throughout life.
What happens in aniridia?
heterozygous mutation of the Pax6 allege resulting in the loss of both iris in the eye.
