Why must an amino acid be activated first before being used for protein synthesis? BecauseGroup of answer choicesThe formation of a peptide bond between free amino acids is not thermodynamically favorableActivation of an amino acid enables its attachment to the tRNA moleculeThe synthetase enzyme only acts on activated amino acids

An amino acid must be activated before being used for protein synthesis for several reasons:

1. The formation of a peptide bond between free amino acids is not thermodynamically favorable: Peptide bond formation involves the condensation of two amino acids, resulting in the release of a water molecule. This process requires energy input to overcome the thermodynamic barrier. By activating the amino acid, the energy required for peptide bond formation is provided.

2. Activation of an amino acid enables its attachment to the tRNA molecule: Transfer RNA (tRNA) molecules play a crucial role in protein synthesis by carrying the activated amino acids to the ribosome. The activation process involves attaching the amino acid to a specific tRNA molecule through an ester bond. This attachment ensures that the correct amino acid is delivered to the ribosome during protein synthesis.

3. The synthetase enzyme only acts on activated amino acids: Aminoacyl-tRNA synthetases are enzymes responsible for attaching the correct amino acid to the corresponding tRNA molecule. These enzymes specifically recognize and bind to the activated form of the amino acid. By activating the amino acid, it becomes a suitable substrate for the synthetase enzyme, allowing for the accurate pairing of amino acids with their corresponding tRNA molecules.

In summary, the activation of an amino acid before protein synthesis is necessary to overcome thermodynamic barriers, enable attachment to tRNA molecules, and ensure recognition by the synthetase enzyme.

An amino acid must be activated before being used for protein synthesis for several reasons:

1. The formation of a peptide bond between free amino acids is not thermodynamically favorable: Peptide bond formation involves the condensation of two amino acids, resulting in the release of a water molecule. This process requires energy input to overcome the thermodynamic barrier. By activating the amino acid, the energy required for peptide bond formation is provided.

2. Activation of an amino acid enables its attachment to the tRNA molecule: Transfer RNA (tRNA) molecules play a crucial role in protein synthesis by carrying the activated amino acids to the ribosome. The activation process involves attaching the amino acid to a specific tRNA molecule through an ester bond. This attachment ensures that the correct amino acid is delivered to the ribosome during protein synthesis.

3. The synthetase enzyme only acts on activated amino acids: Aminoacyl-tRNA synthetases are enzymes responsible for attaching the correct amino acid to the corresponding tRNA molecule. These enzymes specifically recognize and bind to the activated form of the amino acid, ensuring accurate pairing between the amino acid and tRNA. Without activation, the synthetase enzyme cannot effectively catalyze the attachment of the amino acid to the tRNA molecule.

In summary, the activation of an amino acid before protein synthesis is necessary to overcome thermodynamic barriers, enable attachment to tRNA molecules, and ensure proper recognition by the synthetase enzyme.