Transcription

Question 1

RNA polymerase

Answer 1

• -doesnt use a primer!

- -much more error prone than DNA pol., not a big deal since mRNA’s dont stick around forever like DNA

Question 2

RNA Pol. I

Answer 2

• -synthesizes 28S, 18S, and 5.8S rRNA (5S done by Pol. III)

- -

Question 3

Each Ribosomes contains

Answer 3

–one copy of each rRNA: 28S, 18S, 5.8S, 5S

Question 4

RNA Pol. III

Answer 4

• -5S rRNA

- -systhesis of tRNA molecules

Question 5

Cells have multiple copies of which genes?

Answer 5

rRNA and tRNA to produce adequate quantities to support ribosome/protein synthesis

Question 6

Pol. II

Answer 6

mRNA

Question 7

Promoters of RNA synthesis

Answer 7

• -TATA, CAAT boxes or GC rich region

- -A/T rich regions are easier to pull apart

Question 8

Enhancers of RNA synthesis

Answer 8

–enhance transcription but can be found many hundreds of BPs away from gene that is enhanced

Question 9

TFIID

Answer 9

• -made up of many proteins
• -has TBP (TATA box binding protein)
• -binds to DNA and causes distortion
• -signpost for other GTF’s and Pol II

Question 10

Death Cap Mushroom

Answer 10

• -amanita phalloides
• -90% of deaths from mushrooms worldwide
• -alpha-amantin toxin which inhibits Pol. II

Question 11

Rifampicin

Answer 11

• -antibiotic
• -inhibitor of RNA pol
• -Euk. Pol II unaffected by it
• -can selectively kill bacteria
• -good against mycobaterium tuberculosis

Question 12

5’ capping

Answer 12

modifies mRNA and helps cell distinguish mRNA from other types of RNA

Question 13

Spliceosome

Answer 13

• -made up of snRNA and protein

- -protein = scaffold and snRNA = catalytic unit used to splice out introns

Question 14

Export of mRNA from nucleus

Answer 14

• -doesnt occur w/o capping, splicing and polyadenylation
• -nuclear pore recognizes if these modifications have/have not been made and will not export any unmodified mRNA which will be degraded in nucleus

Question 15

Degradation of mRNA

Answer 15

removal of 5’ cap and some of poly-A tail and then ribonucleases degraded mRNA from both ends

Question 16

Beta-Thalassemia

Answer 16

• -incorrect splicing of mRNA
• -mutations that result in reduced synthesis of the Beta-chain of hemoglobin
• -mutation around splice site recognized so another splice site is used

Question 17

PKU

Answer 17

• -cannot convert Phe to Tyr

- -common mutation in PKU Pts. single base change in the 5’ splice donor site of one particular intron

Question 18

HAT vs HDAC

Answer 18

• -HAT’s acetylate histones reducing their negative charge to loosen interactions w/ DNA and promote transcrition
• -HDAC’s de-acetylate histones to condense DNA more around histones
• -lysine residues ususally acetylated

Question 19

DNA methylation

Answer 19

–occurs on cytosine residues and recruits HDACs to de acetylate the DNA

Question 20

3 Types of Gene regulatory proteins and where do they bind?

Answer 20

• -helix turn helix: side chains of AA bind to DNA
• -zinc finger: zinc coordinated to histidine and cysteine
• -leucine zipper: dimer of two alpha-helix form coiled coil, every seventh AA is hydrophobic leucine
• -all bind in major groove!

Question 21

Rubenstein-Taybi Syndrome

Answer 21

–point mutations, small deletions or rearrangements in genes encoding CBP or EP3000

Question 22

Tamoxifen

Answer 22

• -competitive inhibitor of estrogen receptor
• -estrogen receptor when bound w/ estrogen and activate transcription
• -inhibits tumor growth in breast cancer
• -Tamoxifen/receptor complexes still bind to DNA but fail to recruit additional proteins needed to transcribe