ATP, shorthand for adenosine triphosphate, is the standard molecule for cellular energy in the human body. All motion and metabolic processes within the body begin with energy that is released from ATP, as its phosphate bonds are broken in cells through a process called hydrolysis. Once ATP is used, it is recycled through cellular respiration where it gains the needed phosphate ions to store energy again.
TL;DR (Too Long; Didn't Read)
Cellular processes are fueled by hydrolysis of ATP and sustain living organisms.
How Does ATP Work?
Every cell contains Adenosine Triphosphate in the cytoplasm and nucleoplasm. ATP is produced through glycolysis in anaerobic and aerobic respiration. The mitochondria plays a major role in ATP production in the process of aerobic respiration. ATP is the molecule that makes it possible for organisms to sustain life and reproduce.
Body Processes that Require ATP
ATP macromolecules are referred to as the main "energy currency of the cell" and transfer potential energy on the cellular level through chemical bonds. All metabolic processes that occur on the cellular level are powered by ATP. When ATP releases one or two phosphate ions, energy is released as the chemical bonds between the phosphate ions are broken. Most ATP in the body is made in the inner membrane of the mitochondria, an organelle that powers the cell.
Sciencing Video Vault
According to TrueOrigin, nearly 400 pounds of ATP are used daily by the ordinary human with a 2,500-calorie diet. As an energy source, ATP is responsible for transporting substances across cell membranes and performs the mechanical work of muscles contracting and expanding, including the heart muscle. Without ATP, body processes that require ATP would shut down and the organism would die.
Understanding ATP and ADP
One of the many uses of ATP is the physical movement of muscles. During muscular contraction, myosin heads attach to bonding sites on the actin myofilaments through the use of an ADP (adenosine diphosphate) cross-bridge, where the extra phosphate ion from ATP is released. ADP and ATP differ in that ADP lacks the third phosphate ion that gives ATP its energy-releasing capabilities.
Energy stored from the releasing of the phosphate allows the myosin to move its head, which is currently bonded to, and thus moves with the actin. ATP bonds with the myosin head after muscle contraction is complete and is converted to ADP (adenosine diphosphate) with an extra phosphate ion. Strenuous exercise can deplete ATP in heart and skeletal muscles resulting in soreness and fatigue until normal ATP levels are restored.
DNA and RNA Synthesis
When cells divide and undergo the process of cytokinesis, ATP is used to grow the size and energy content of the new daughter cell. The ATP is used to trigger DNA synthesis, where the daughter cell receives a complete copy of the DNA from the parent cell. ATP is a key component in the DNA and RNA synthesis process as one of the key building blocks used by RNA polymerase to form the RNA molecules. A different form of ATP is converted to a deoxyribonucleotide, known as dATP, so that it can be incorporated into DNA molecules for DNA synthesis.
By bonding with certain parts of protein molecules, ATP can act as an On-Off switch for other intracellular chemical reactions and can control messages that are sent between different macromolecules within the cell. Through the bonding process, ATP causes another part of the protein molecule to change its arrangement, thus making the molecule inactive. When ATP releases its bond from the molecule, it reactivates the protein molecule. This process of adding or removing a phosphorus from a protein molecule is referred to phosphorylation. One example of ATP being used in intracellular signaling is the release of calcium for cellular processes in the brain.