Final answer:
Amino acids stimulate protein synthesis by increasing their uptake in muscle cells, aided by growth hormone and IGFs, and are essential for muscle growth and repair, especially during exercise, stress, or starvation.
Step-by-step explanation:
Amino acids stimulate protein synthesis in muscle by serving as the building blocks for new proteins. During exercise or periods of stress, the body signals for protein synthesis by increasing amino acid uptake by muscle cells. Growth hormone and Insulin-like growth factors (IGFs) play a pivotal role in this process.
Growth hormone directly accelerates protein synthesis in skeletal muscle and bones, while IGF-1, activated by growth hormone, promotes further uptake of amino acids by muscle cells, facilitating new protein formation. Amino acids are also important during starvation, as they can be derived from the breakdown of skeletal muscle proteins.
The process includes activation of amino acids, where amino acids bind to their specific tRNA molecules with the help of aminoacyl-tRNA synthetase enzymes, using ATP in the process. Once attached, tRNAs transport the amino acids to the ribosome, where they are incorporated into the growing peptide chain.
In summary, the presence of amino acids in the blood triggers a cascade of hormonal actions leading to increased protein synthesis, crucial for muscle growth and repair.