RNA

Question 1

Structural genes that are transcribed + promoter region + all regulatory regions

Answer 1

Operon

Question 2

Transcription factors must bind to the promoter region in order for transcription to take place. What are the promoter regions?

Answer 2

• -75 CCAAT box
• -25 Hogness/TATA box
• -10 Pribnow/TATAAT box

Question 3

This binds repressors (stops transcription) or inducer (starts transcription) and is located between the promoter region and the start site

Answer 3

Operator region

Question 4

This has an enhancer region and repressor region. It increases or decreases the RATE of transcription when bound by protein factors. Location may be close to, far from, or within the promoter region

Answer 4

Response elements

Question 5

What are the common DNA-binding motifs?

Answer 5

• Helix-loop-Helix
• Helix-turn-Helix
• Zinc finger
• Leucine zipper protein

Question 6

What can be produced by prokaryotes for energy in the absence of glucose?

Answer 6

Beta-galactosidase to metabolize lactose

Question 7

What is the situation in which the lac operon is on

Answer 7

• Absent glucose

- excess lactose

Question 8

Describe the lac operon?

Answer 8

• If glucose present then no CAP (catabolite activating protein) . . CAP facilitates RNA polymerse binding
• If lactose is absent then repressor (allolactose) is present
• If lactose is present then repressor moves and then tracription of beta-Galactose can take place if there is no glucose

Question 9

describe the rho independent mechanism of termination of prokaryotic RNA transcription

Answer 9

• regocnition of termination region in DNA
• GC-rich DNA –> GC same-strand binding forms stem-loop (hairpin) in RNA –> pause in RNA polymerase –> subseqent weak RNA bonds (uracil rich regions) –> separation of RNA polymerase

Question 10

Where are the different RNAs synthesized?

Answer 10

• mRNA: nucleoplasm
• tRNA: nucleoplasm
• rRNA: nucleolus

Question 11

What is the start codon in eukaryotes and what does it encode?

Answer 11

• AUG

- methionine

Question 12

what are the stop codons?

Answer 12

• UGA
• UAG
• UAA

Question 13

In eukaryotes, what are the different RNA polymerases and what do they make?

Answer 13

• I: rRNA
• II: mRNA
• III: tRNA

Question 14

what is alpha-amanitin?

Answer 14

• Mushroom toxin
• Inhibits RNA polymerase II
• Hepatotoxicity, liver failures

Question 15

what is the RNA polymerase in prokaryotes?

What drug inhibits it?

Answer 15

• only have 1

- rifampin

Question 16

To make mRNA from hnRNA you have to do what 3 things?

Answer 16

• Cap on 5’ end
• polyadenylate 3’ end
• Remove introns

Question 17

Describe the 5’ cap on mRNA

Answer 17

• 7-methyl-guanosine

- provided by S-adenosyl-methionine

Question 18

Describe the polyadenylated 3’ end on mRNA

Answer 18

• 200-250
• provided by poly-A-polymerase
• AAUAAA starts this

Question 19

What removes the introns to form mRNA?

Answer 19

splicosomes