RNA

Question 1

What are the key differences or RNA from DNA?

Answer 1

T is replaced with U.

Ribo nucleic acid (no deoxy). Usually single stranded.

Question 2

Which organisms mRNA is polycistronic? monocistronic>

Answer 2

Poly=Prokaryotic
Mono=Eukarotic

Poly=code fr more than one polypeptide chain.

Question 3

What is the function of mRNA? Structure?

Answer 3

Nucleotide triplets (codons) pair with tRNA to code for a specific amino acid.

Poly-A tail, 5’ cap.

Question 4

What is the function of tRNA? Structure?

Answer 4

Translates mRNA into proteins.

1. Acceptor Stem: Site where specific amino acid is linked
2. Anticodon Loop: Base pairs with codon on mRNA

Question 5

What is rRNA? Structure?

Answer 5

Ribosomal RNA is catalytic site for ribosome.

5S, 16S, and 23S units.

Question 6

What is a gene?

Answer 6

A segment of DNA that functions to generate RNA.

Question 7

RNA polymerase synthesize RNA in which direction? Unlike DNA polymerase, it doesn’t have what?

Answer 7

5’ to 3’.

Doesn’t require a primer, and does not have Exonuclease activity.

Question 8

What is a Holoenxyme? Promotor?

Answer 8

Holo= Core enzyme (RNA polymerase) and Sigma
Promoter= binding sites in DNA where transcription begins.

Question 9

Describe the step of prokaryotic initiation, and enzymes invovled.

Answer 9

Sigma protein subunit must bind to DNA. it acts as regulatory factor, guiding RNA poly to specific promoter sequences on DNA strand.

Question 10

Describe the prokaryotic Transciption step. Elongation.

Answer 10

• Promotor, or Regulatory region, is found upstream of coding sequence.
• DNA consensus is recognized by RNA poly
• Elongation occurs.

Question 11

What is different in Eukaryotic transciption?

Answer 11

• Transcription factors instead of sigma.
• Complex promotors and regulatory regions.
• 3 RNA polymerases.

Question 12

What do the 3 RNA polymerases work with?

Answer 12

I=pre-rRNA
II= mRNA
III= tRNA and 5s rRNA

Question 13

Where does eukaryotic mRNA processing takes place where? mRNA translation?

Answer 13

processing=nucleus

translation=cytoplasm

Question 14

What is 5’ mRNA capping? What does it do?

Answer 14

5’ mRNA capped with modified guanosine.

• Stabilizes message
• Exit from nucleus
• Promoting efficient translation of mRNA to protein.

Question 15

What is polyadenylation? What does it do?

Answer 15

Addition of A’s to 3’ end.

• Transcription termination
• Translation
• mRNA stability
• nuclear export of mRNA

Question 16

What is intron splicing?

Answer 16

Pre-mRNA is spliced to remove introns.

Question 17

What are introns?

Answer 17

non-coding intervening sequencing.

Question 18

Where does intron splicing take place?

Answer 18

Spliceosome.

Question 19

What is alternative splicing?

Answer 19

Production of 2 or more distinct proteins from a single gene.

Question 20

What is reverse transcriptase?

Answer 20

Synthesizes DNA from viral RNA. Extremely error prone and mutations.