Protein- Reynolds

Question 1

Protein synthesis

Answer 1

mRNA is translated into aa sequence

Question 2

mRNA sequence corresponds to the non-template strand of DNA except

Answer 2

U in place of T in RNA

Question 3

Codons

Answer 3

• triplet nucleotides bind to anticodon
• 5’ to 3’
• each codon codes for one specific aa

Question 4

degenerate Codon

Answer 4

Multiple ways to code for the same aa

Question 5

Start codon

stop codon

Answer 5

• Start codon
  
  • AUG
  • corresponds to N-terminus of the protein
• Stop codon
  
  • UAA, UAG, UGA
  • corresponds to C-terminus of the protein

Question 6

Reading Frames

Answer 6

• mRNA= 3 potential reading frames
• DNA= 6 potential reading frames (3 each strand)

Question 7

Use aa table

Answer 7

first letter vertical

second letter horizontal

third letter find in the box

Question 8

Splice site mutation

Answer 8

alter the way in which introns are removed

Question 9

Requirements for protein synthesis

7

Answer 9

1. aa
2. tRNAs
3. aminoacyl-tRNA synthetases
4. mRNA
5. Ribosomes
6. Protein factors
7. ATP and GTP

Question 10

Steps in protein synthesis

5

Answer 10

1. Activation of amino acids
2. Initiation
3. Elongation
4. Termination
5. Folding and posttranslational processing

Question 11

tRNA structure

Answer 11

• reads the codons
• stucture
  
  • acceptor stem→ ACC
  • anticodon→ tRNA bp w/ codon in mRNA antiparallely
  • unique nucleotide bases

Question 12

Wobble

Answer 12

• allows one anticodon to base pair with several different codons
• If tRNA anticodon recognized only one codon, cells would have a different tRNA for each codon (which they do not)
• First 2 bases of codon form strong H-bonding with anticodon
• Codons that differ in the first two bases require different tRNAs

Question 13

Ribosome

Answer 13

• mainly rRNA (65%) and some protein
• Different size subunits
• most RNA is rRNA (80%)→ tRNA (15%)→mRNA (5%)

Question 14

AA activation/tRNA charging

Answer 14

Aminoacyl-tRNA synthetases

• aa activation/charge to cognate tRNA
• specific for one aa and one or more tRNAs

Question 15

Initiation

SD

Answer 15

Shine-Dalgarno sequence (SD)

• only in prok
• euk has 5’ cap
• purine rich sequence upstream of AUG

Question 16

Initiation Requires

7

Answer 16

1. 30S ribosomal subunit
2. 50S ribosomal subunit
3. mRNA
4. fMet-tRNAfMet
5. GTP
6. Mg+2
7. Initiation factors

Question 17

Initiation complex

Answer 17

A site = aa attaches

P site=form the peptide bond

E site=Exit

(in euk the introns are gone and the cap is already on)

Question 18

what recruits the unique fMET-tRNA fMET (Formyl Met)

Answer 18

AUG, start codon

Question 19

Elongation 3 steps

Answer 19

1. Binding of incoming aminoacyl-tRNA
2. Peptide bond formation
3. Translocation

adding aa to carboxyl end of polypeptide chain N→C direction

Question 20

Elongation requires

4

Answer 20

1. Initiation complex
2. Aminoacyl-tRNAs
3. Elongation factors
4. GTP

Question 21

Polysomes

Answer 21

In prokaryotes, several ribosomes translating an mRNA simultaneously

Question 22

coupled transcription/translation

Answer 22

prok. transcription and translation are coupled
euk. mRNAs must leave the nucleus for translation

Question 23

Termination

Answer 23

• stop codons occupies the A site
  
  • Release factors (RF) hydrolyze the terminal peptidyl bond
  • Eelease polypeptide
  • dissociation of the ribosome