Final answer:
The correct statements about tRNA are that an amino acid is covalently attached to the 3' end, there are 20 distinct aminoacyl-tRNA synthetases, and AMP is released during the tRNA charging process. The statement about tRNA with methionine binding to the A site during initiation is incorrect; it binds to the P site.
Step-by-step explanation:
Correct statements about tRNA include:
- A. An amino acid is covalently attached to the 3' end of a tRNA. This is part of the tRNA "charging" process.
- C. There are 20 different aminoacyl-tRNA synthetases. Each is specific for one of the 20 amino acids used to synthesize proteins.
- D. AMP is released when an amino acid is attached to a tRNA during charging. This is a result of amino acid activation involving ATP hydrolysis.
However, statement B is incorrect because the tRNA charged with methionine does not bind to the A site of a ribosome during the initiation phase of translation. Instead, it binds to the P (peptidyl) site as part of the initiation complex during the start of protein synthesis in eukaryotes.