An enzyme is a biological catalyst. It speeds up reactions by lowering the activation energy needed for a certain reaction. It does this by bending certain bonds that need to be broken or creating certain environments needed in a reaction.

They are ussually named by adding "-ase" to the substrate (what is being catalyzed). 

Ex. - cellulose is substrate -> enzyme = cellulase

A cofactor is something that is supplied or supplies for the enzyme to work but is not readily available at the active sight (where the substrate enters). When organic molecules are a cofactor they are called coenzymes. 

Cofactors are usually divalent cations (Ex. Mg^2+)

Ex. Coenzyme -> Thiamine pyrophosphate supplies an acidic carbon

Inhibiton in terms of enzymes occurs when an inhibitor prevents a reaction from happening on the enzyme.

In competitive inhibition, the inhibitor blocks the active site (also called catalytic site). Competitive inhibitors are shaped like the substrate.

Some enzymes have an allosteric site, seperate from the active site. In non-competitive inhibition, the inhibitor fits into the allosteric site and prevents the reaction from occuring, because its presence causes the active site to close.

An allosteric inhibitor (also called a non-competitive inhibitor) prevents the enzyme from working when placed in the site.

An allosteric activator stabilizes the active site when in the allosteric site. It can do this in many ways, like increasing the bonding affinity of substrates.

ATP is Adenosine triphosphate. It is like a nucleotide, accept with 3 phosphate groups.

The names of the phosphate groups (in order of distance away from the ribose) is alpha, betta and gamma.

When the the gamma phosphate is hydrolyzed, (7.3 kilocalories/mol) are released. 

ATP turns to ADP and the gamma phosphate is transferred to the substrate in an endogernic reaction.

"Coupling of energy" is when the energy given off from the reaction is used to do work within the cell rather than just given off as heat.