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Uses and Importance of ATP in Organisms
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Uses and Importance of ATP inOrganisms
Uses and Importance of ATP in Organisms
ATP as the Main Energy Source
ATP is the main energy source for both plants and animals.
It allows organisms to carry out processes within cells.
ATP is a phosphorated macromolecule made up of adenine, ribose, and phosphates.
It is a good energy storage molecule with three phosphate groups, which have unstable
bonds and a low activation energy.
When ATP is hydrolyzed by ATP hydrolase, it releases a large amount of energy.
The energy released from ATP hydrolysis is used for various cellular processes.
ATP in Protein Activation
ATP can be used to transfer and activate proteins by attaching a phosphate group
(phosphorylation).
For example, ATP can activate P53, a tumor suppressor transcription factor.
Phosphorylation of P53 arrests the cell cycle and can trigger apoptosis.
ATP in Muscle Contraction
ATP provides the energy for muscle contraction.
Muscle contraction starts with a tropomyosin molecule preventing a myosin head from
attaching to the binding site on the actin molecule.
Calcium ions released from the endoplasmic reticulum cause the tropomyosin molecule to
change shape and expose the binding sites on the actin molecule.
The myosin head attaches to the actin filament and changes angle, moving the actin filament
along.
The ADP molecule is released, and ATP fixes to the myosin head, causing it to detach from
the actin filament.
Hydrolysis of ATP to ADP by ATPase provides the energy for the myosin head to resume its
normal position and repeat the cycle.
ATP in Movement and Digestion
ATP is important for the movement of different parts of organisms, such as isotonic
contractions in humans.
ATP is essential in the digestion and absorption of glucose in the ileum.
During this process, ATP is used to transport sodium ions out of epithelial cells by the
sodium-potassium pump.
The higher concentration of sodium ions in the lumen of the intestine compared to inside the
epithelial cells allows sodium ions to diffuse into the cells along with glucose molecules
through co-transporter proteins.
Glucose then passes into the blood plasma by facilitated diffusion.
ATP is used as an energy source for the ion pumps involved in this process.
ATP in Synaptic Transmission
ATP is involved in synaptic transmission, particularly in cholinergic synapses.
Cholinergic synapses use the neurotransmitter acetylcholine.
An action potential causes calcium ions to enter the presynaptic neuron, leading to the
release of acetylcholine into the synaptic cleft.
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