The Different Ways Organisms Use Atp.

Adenosine triphosphate is the immediate source of energy in an organism. Animal cells use ATP in many different ways such as synthesis of new cells, synthesis of amino acids, active transport and for respiration. Plant cells use ATP for respiration, photosynthesis, making cell walls

Direct active transport takes place in cells of organisms this is when ATP breaks down into ADP (adenosine di-phosphate), the phosphate molecule attaches onto the carrier protein. An example of this is the uptake of ions by root cells in plants, this achieves a lower water potential inside the roots leading to movement of plants inside the cell. Consequently, the carrier protein changes shape and allows molecules to enter the cell. Co- transport takes place in the small intestine, where epithelial cells pump out sodium ions into the lumen (by a sodium potassium pump), this requires ATP as it goes against the concentration gradient. Sodium ions then travel back down to the cell carrying a glucose molecule which can be used for respiration.

In photosynthesis, during the Calvin cycle ATP is needed to reduce glycerate-3-phosphate into triose phosphate, this can further be made into glucose, and other organic molecules. Respiration is the most important process in an organism this is where glucose is broken down to produce ATP. Glycolysis is the first stage of respiration this is when two molecules of ATP are needed to break down the hexose sugar (C6H1206) into two molecule pyruvate. The overall process of respiration provides 36 ATP molecules which the organism can use. Metabolic processes such as homoeostasis also require ATP to maintain a constant internal environment.

Homeostasis can take place when blood glucose level drops below normal, one way the beta cells in the pancreas ensure that blood glucose is kept constant is by adrenaline. Adrenaline attaches to the receptor site on the surface of the cell, which forms and receptor hormone complex therefore activating an enzyme inside the cell. Furthermore this enzyme converts ATP into cyclic AMP, which activates a secondary messenger model and activates other enzymes which convert glucagon into glucose.

Muscle cells need ATP to maintain the contraction action, when myosin heads bind to the actin site it changes its direction of movement pulling the actin filament. However it stays in this position so no other movement can occur, ATP attaches onto the myosin head and causes it to detach from the actin molecule. This is done by ATPase which breaks down the ATP molecule into ADP, the energy released from this hydrolyses reaction is used to detach the myosin head so that it can reattach further along the actin filament. If ATP is not released into the sarcomere then myosin head stay in the same position, this causes a condition called rigor mortis , this causes the muscles to become stiff after death. ATP is essential in muscle cells to keep up the movement, and other metabolic processes.

In conclusion, many organisms use ATP to maintain their internal environments, this can be done in various ways such as respiration, photosynthesis. ATP is useful in an organism as it is broken down in a single step process of hydrolysis, it is found in every single cell.