Gene regulation

Question 1

3 eukaryotic RNA polymerases

Answer 1

Pol I - transcribes rRNA
Pol II - mRNA
Pol III - tRNA, snRNA

Question 2

Enhancers

Answer 2

interact with transcription process (bind to activator protein)

Question 3

Patches on chromatids

Answer 3

Euchromatin - lightly stained, less condensed, transcriptionally active

vs Heterochromatin

Question 4

Post-transcriptional mechanisms for gene regulation

Answer 4

Alternative splicing - diff proteins depending on which exons are spliced out (ex: tropomyosin has 11 exons, diff tissues miss diff exons)

Question 5

RNA stability

Answer 5

polya.. 5’ g cap?

Ribosome searches for start codon; regions before while its looking = 5’ untranslated region, controls stability of mRNA

present in after 3’ end

Question 6

RNA interference

Answer 6

micro RNAs (22 bp) form 3D structures - protein - looks for complementary sequence in mRNA (usually in untranslated region) - regulates translation of that RNA

Question 7

Post-translational control

Answer 7

proteins are destroyed on schedule by the proteosome (ubiquitin tag on damaged/whatever protein = mark of death)

Question 8

Gene cloning

Answer 8

moving a single gene from one organism to another

• to make an organism express a new gene –> new phenotype
• to understand a phenotype

Question 9

Restriction Endonuclease: BamHI

Answer 9

enzymes that cut phage DNA (bacteria modifies its DNA after release to protect itself) - doesn’t cut straight, leaves a ragged end

–> we used ragged end to insert DNA (insulin)

Question 10

Ligation

Answer 10

DNA Ligase used to link sugar-phosphate backbone (after inserting insulin gene w BamHI)

Question 11

Intron problem

Answer 11

Make DNA copy of mRNA (lacking introns) with reverse transcriptase (instead of cloning gene in chromosome in eukaryote)

reverse transcriptase needs 3’ hydroxyl (DNA polymerase) - make oligo T which binds to poly-a tails (which we know all mRNAs have)

RNA –> RNA & DNA primer –> RNA & cDNA –> cDNA –> double strand cDNA

Question 12

Hybridization

Answer 12

Melt double strand apart - bind to complementary radioactive sequence

“stickiness” of DNA depends on number of H-bonds (GC pairs have 3, TA have 2)

Question 13

COncatemers?

Answer 13

2 insulin genes in a bacteria cuzthey sticky to eachother

Question 14

How to make sure insulin gene is inserted in right orientation

Answer 14

Use restriction enzyme and find out where it cut