These enzymes are proteins but not all proteins are enzymes. The reactions can be chartered or ordered into different pathways. Certain organisms are going to have unique pathways to them. Virus, bacteria, humans have unique ways of reproducing. Most reaction need an initial energy input to begin call the energy of activation.
Enzymes allow chemical reactions to occur at greater speeds and lower temperatures.
They are very specific and there are more than 2000 known. The substrate is the molecule on which an enzyme acts. There is a reaction in which the combination of carbon dioxide and water produce carbonic acid. This occurs naturally in the ocean but the human body has an enzyme carbonic anhydrase. 6x105 molecules of carbonic acids are produced per second because of the presence of this enzyme.