Elongation steps

Question 1

Step one

Answer 1

A tRNA carrying the next AA
binds to the A site of the
ribosome. The tRNA in the P
site holds the current chain.

Question 2

Step two

Answer 2

A peptide bond forms
between the AA at the A site
and the last AA in the chain.

Question 3

Step three

Answer 3

The polypeptide chain is
transferred to the tRNA at the
A site.

Question 4

Step four

Answer 4

The ribosome moves down
the chain three bases, shifting
the tRNAs from sites A 🡪 P
and P 🡪 E.
The tRNA at the E site is
discharged and the whole
cycle repeats.