tRNA Charging

Before an amino acid can be incorporated into a growing polypeptide, it must first be attached to a molecule called transfer RNA, or tRNA, in a process known as tRNA charging. The charged tRNA will then carry the activated amino acid to the ribosome. The process begins when the enzyme aminoacyl-tRNA-synthetase, depicted in blue, catalyzes an energy-releasing reaction between an amino acid and a molecule called adenosine triphosphate, or ATP, In this step, ATP loses two phosphates and becomes linked to the amino acid as adenosine monophosphate, or AMP. This initial reaction, although it is not shown here, is necessary because it provides energy to drive subsequent steps in the tRNA charging process. Here, the tRNA molecule is represented by the colored wavy lines and binds to the aminoacyl-tRNA-synthetase. An amino acid, shown as the green sphere, also binds to the enzyme, losing its AMP molecule, depicted as the small hook. Using the energy released from the loss of AMP, the aminoacyl-tRNA-synthetase attaches the amino acid to the tRNA molecule and then dissociates from it.

Question 1: Before an amino acid can be incorporated into a growing polypeptide, it must first be attached to a molecule called transfer RNA, or tRNA. What is this process known as?
  1. RNA charging
  2. tRNA charging
  3. tRNA attachment
  4. tRNA processing


Answer 1 Answer – (b) tRNA charging

Question 2: How does the tRNA charging process affect amino acids and tRNA?
  1. Charging of the amino acid and elongation of the tRNA.
  2. Charging of the amino acid and elongation of the tRNA.
  3. Activation of the amino acid and charging of the tRNA.
  4. None of the above.


Answer 2 Answer – (c) Activation of the amino acid and charging of the tRNA.

Question 3: In the process of tRNA charging, ATP loses ___________ phosphates to become AMP?
  1. 1
  2. 3
  3. 4
  4. 2


Answer 3 Answer – (d) 2