Final answer:
Amino acids can be synthesized in two main ways: in the body, where nonessential amino acids are made through specific anabolic pathways, and in the laboratory, where they are created from simpler molecules with the aid of energy simulating natural events.
Step-by-step explanation:
Amino acids, the building blocks of proteins, can be synthesized in the body through two main pathways. The first pathway involves the synthesis of nonessential amino acids inside the human body. For example, the amino acids glutamate, glutamine, and proline share an anabolic pathway starting with the enzyme glutamate dehydrogenase, which adds ammonia to α-ketoglutarate with the help of NADPH to form glutamate. Glutamate then acts as a nitrogen donor for the production of other amino acids.
The second pathway refers to the laboratory synthesis of amino acids. This is typically done by combining simple molecules such as ammonia, water, methane, and hydrogen, and providing energy through processes that imitate natural phenomena, such as lightning strikes or volcanic eruptions. These methods have been key in understanding the possible origins of life and amino acids on Earth.
Furthermore, amino acids can be shunted into energy production pathways like the Krebs cycle, especially during starvation, where they are catabolized into intermediates such as pyruvate and acetyl CoA.