Curious Jess said:
Hopefully someone can assist me here as I've searched the internet (google searches, wikipedia, youtube videos) in vain for this answer and yet I'm still stumped about just what is the actual ''energy'' being transferred from when after ATP leaves the ETC and then binds with a receptor (Organelles, DNA Transcription etc.) and releases it's high energy phosphate to then energize that cellular component. So what is actually inside that phosphate molecule? Is it transfering electrons?
Thanks!
Jess
Yes, the general answer is moving electrons. Somewhere in the reaction there is a step where moving electrons, most probably from the phosphate, move an ATPase molecule that does work. However, the detailed answer involves physical chemistry.
What you are asking is really a question about physical chemistry, rather than biology. The most general answer regards how energy is moved around in chemical reaction.
When a chemical bond is broken, energy is absorbed as chemical potential energy. When a chemical bond is formed, chemical potential energy is released by changing it to some other form. The form the energy takes on release depends on the chemical reaction.
One can visualize the process as chemical energy being first transformed into kinetic energy of the electrons in the bond. The electrons because of their electric charge move around the surrounding nuclei and electrons. So the energy gets turned into vibrational, rotational and translational kinetic energy of molecules. Because the electrons are electrically charged, moving around the electrons can also generate electromagnetic energy like light.
Thus, chemical reactions absorb and release energy by the motion of electrons. The moving electrons drag the nuclei in the molecules around. For example, a proton can be moved in a direction against the electric field in a cell membrane. This results in electrical potential energy.
The ATP molecule is connects temporarily with an ATPase, which is an enzyme that speeds up the decay of ATP. The bond between the adenosine and the phosphate is broken by absorbing some of the kinetic energy from the ATPase. The formation of bonds between the phosphate anion, the adenosine diphosphate cation and the ATPase releases energy that forces the ATPase molecule to move. The specific motion of the ATPase molecule then forces other molecules and ions to move in certain directions, absorbing most of the energy. The phosphate and the adenosine diphosphate disconnect from the ATPase molecule, absorbing most of the remaining energy.
One example would be the proton pump molecules that exist in the cell membrane. In the case of a proton pump, ATPase, when the ATP loses a phosphate the ATPase is forced to spin. Thus, chemical potential energy in the ATP is turned to rotational kinetic energy in the ATPase. The spinning ATPase molecule forces a proton to move against a chemical gradient, or electric field. Thus, the rotational kinetic energy is turned into electrical potential energy.
Different types of ATPase exist in the muscle cells, the nerve cells, and other cells. There are many such reactions known, and probably a lot that are unknown.
http://en.wikipedia.org/wiki/ATPases
“ATPase
ATPases are a class of enzymes that catalyze the decomposition of adenosine triphosphate (ATP) into adenosine diphosphate (ADP) and a free phosphate ion. This dephosphorylation reaction releases energy, which the enzyme (in most cases) harnesses to drive other chemical reactions that would not otherwise occur. This process is widely used in all known forms of life.
Some such enzymes are integral membrane proteins (anchored within biological membranes), and move solutes across the membrane, typically against their concentration gradient. These are called transmembrane ATPases.
…
The ATP synthase of
mitochondria and chloroplasts is an anabolic enzyme that harnesses the energy of a transmembrane proton gradient as an energy source for adding an inorganic phosphate group to a molecule of adenosine diphosphate (ADP) to form a molecule of adenosine triphosphate (ATP).
This enzyme works when a proton moves down the concentration gradient, giving the enzyme a spinning motion. This unique spinning motion bonds ADP and P together to create ATP.
ATP synthase can also function in reverse, that is, use energy released by ATP hydrolysis to pump protons against their thermodynamic gradient.”
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