Proteinbiosynthesis Translation

Question 1

What are the steps of initiation in translation?

Answer 1

1. small subunit binds to mRNA‘s recognition sequence (5‘ cap), forming initiation complex.
2. small subunit moves along mRNA until it encounters start codon (AUG)
3. Methionine-loaded tRNA with complementary base triplet to start codon binds to mRNA
4. Large subunit binds to mRNA
5. Methionine-loaded tRNA occupies P site, initiating elongation

Question 2

What steps are involved in elongation during translation?

Answer 2

1. second tRNA (loaded with amino acid) binds next to start codon, occupying A site of ribosome‘s large subunit
2. peptide bond formation occurs, connecting both amino acids
3. Ribosome moves one step further (in the 3‘ direction) causing unloaded tRNA to occupy E site and second tRNA to occupy P site
4. At E site, tRNA dissociates from ribosome and returns to cytoplasm to be reloaded with an amino acid
5. this process continues until a stop codon enters A site

Question 3

How does termination occur in translation?

Answer 3

1. stop codon does not code for an amino acid
2. stop tRNA binds to A site
3. release factor (eRF) causes release of protein
4. Ribosome disassembles
5. mRNA departs

Question 4

Codon

Answer 4

mRNA

Question 5

Anticodon

Answer 5

tRNA