Translation

Question 1

Translation Overall

Answer 1

mRNA is transported from the nucleus into the cytoplasm

mRNA is translated by ribosomes to produce polypeptide chains

Question 2

tRNA

Answer 2

tRNA carries amino acids to the ribosome

Anticodon binds tRNA with mRNA

Wobble position: the first 2 letters create a bond strong enough to transfer the amino acid, even though the last ones do not bond

Question 3

Ribosomes

Answer 3

Ribosomes are composed of two subunits: large subunit and small subunit

There are special binding sites on the ribosome:
A (aminoacyl) site: binds to the aminoacyl-tRNA carrying the incoming amino acid
P (peptidyl) site: binds to the tRNA attached to the growing peptide chain
E (exit) site: binds the tRNA that carried the previous amino acid added

Question 4

Translation Initiation

Answer 4

Once the mRNA transcript reaches the cytoplasm, it is ready to be translated

Initiation has three steps
Initiator methionine-tRNA forms a complex with the small ribosomal subunit
The complex binds to the 5’ cap of mRNA and scans for AUG codon
Once AUG is located, the large ribosomal subunit completes the ribosome
STARTING TRANSLATION PROCESS

Question 5

Elongation Translation

Answer 5

Elongation has four steps
tRNA with methionine attached binds onto P site
The incoming aminoacyl-tRNA binds onto A site and the methionine is cleaved off and transferred onto the incoming amino acid (by peptidyl transferase)
The ribosome moves along the mRNA to the next codon and the previous two tRNA occupy the E site and P site
The empty tRNA is released from the ribosome

Question 6

Termination for translation

Answer 6

Termination occurs when the A site arrives at a stop codon

When a stop codon appears, a protein release factor binds

Polypeptide chain is detached and ribosomal subunits separate