The diagram represents some experimental steps used in the production of large amounts of human growth hormone - HSC - SSCE Biology - Question 19 - 2020 - Paper 1

The correct answer is D. Restriction enzymes can produce sticky ends on both bacterial and human DNA.

Explanation:

Restriction enzymes play a crucial role in genetic engineering by cutting DNA at specific sequences, creating sticky ends that facilitate the insertion of foreign genes into plasmids. This is essential for producing large amounts of human growth hormone in bacteria, as the sticky ends help ensure that the human DNA can be incorporated into the bacterial plasmid effectively. Without this mechanism, successful cloning and protein expression would not be possible.