Translation

Question 1

Feature of the Genetic Code

Answer 1

• Triplet Code
• Non-overlapping (reading frame sets the codon sequence)
• Universal Code

Question 2

Codons to Know:

Answer 2

AUG - Start (Met)
UAG - STOP
UAA - STOP
UGA - STOP

Question 3

Prokaryotic Translation

Answer 3

1. Small subunit identifies Shine-Dalgarno sequence (via initiation factors) and attaches at start codon
2. tRNA-fMet attaches to the P-site on the small subunit
3. The large subunit attaches
4. Next tRNA attaches to the A-site
5. Peptidyl transferase catalyzes formation of peptide bond
6. The uncharged tRNA leaves the P-site via the E-site and the mRNA shifts down
7. Stop codon recruits a GTP dependent release factor to separate the subunits and release the protein

Question 4

Wobble Rules

Answer 4

At the third base in a codon…

1. Normal base pairing occurs
2. G and U pair
3. An I (on the anticodon only) will pair with A, U, or C

Question 5

Eukaryotic Translation Differences (6)

Answer 5

1. Small subunit binds at G-cap via CAP binding proteins
2. Usually the first AUG after the CAP
3. Usually start codon within 40 bases of the CAP
4. Start codon is optimally (but not always) in a Kozac sequence
5. Poly-A Binding Proteins are present at 3’ end
6. Initial tRNA-Met has a slightly different structure than tRNA-Met

Question 6

Differences in Mitochondrial Translation

Answer 6

1. Initiates with fMet

2. Slightly different coding dictionary (relies on Wobble)