How Enzymes Work, Essay Example

Enzymes are proteins that speed up chemical reactions. Obviously to understand that statement you need to know what proteins are, and know the basics of chemical reactions.

Take two or more elements known to be necessary to life, like carbon, hydrogen, nitrogen, or oxygen and put them together. When different volumes of different elements combine, they always do so in certain proportions to form definite compounds, like hydrogen and oxygen. Two of the former and one of the latter will produce water. Now you have a biochemical compound. For a biochemical compound to also be a protein, it must contain large molecules (called polymers) of amino acids, which form themselves into chains built from the elements carbon and nitrogen that we now add to the hydrogen and oxygen mix. (All four elements are necessary.) Amino acids are the basic units of proteins, and proteins are what life physically consists of, from hair to bones to skin to blood to muscle to . . . enzymes. When protein is eaten, digestion breaks it back down into free units that the body then reassembles into whatever new proteins are needed. Twenty amino acids make many thousands of unique proteins, each with its own unique 3-dimensional shape that determines what it can do.

The basic unit of all life is the biological cell. For life to be supported within a cell, biochemical reactions within it must take place at a certain rate. The sum of those biochemical reactions throughout a body is called its metabolism. Each cell must maintain a certain metabolic rate, depending on its function. This is where enzymes come in. Without them, certain reactions would take place much slower or not at all. In many chemical reactions, when one element or compound changes another, it is itself changed in the process. Not so with enzymes. They speed up reactions but are not changed in the process. This is why they are called catalysts instead of reagents, which, by contrast, are themselves consumed by the reactions they initiate.

Catalysts (and reagents) need something to react with. Enzymes react with molecules called substrates. For there to be effective reactions between them, there must be enough of them. So clearly, a sufficient and balanced quantity of both enzyme and substrate is necessary for optimal performance. A lack of one or the other, or both, will result in cellular dysfunction or death. Temperature also determines reaction, because as mentioned above, proteins assume specific shapes. Their shapes determine how they link with their substrates undergoing catalysis. Excessive heat will degrade a protein’s shape and so hinder its ability to act as a catalyst. Finally, the relative amount of acidity or basicity in the cell, called pH, can effect amino acids.

The catalytic reactions that enzymes induce don’t directly release the kind of energy a cell needs to live and work. That process occurs during cellular respiration, a general term describing two distinct metabolic phases: 1) catabolism, which, starting with the presence of oxygen, converts food into ATP (adenosine triphosphate) energy and so creates waste byproducts such as carbon dioxide, urea and heat; and 2) anabolism, which puts that energy to work by, among other things, building the cell’s many components, such as the two nucleic acid molecules controlling heredity: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid); and of course our amino acids and their resultant proteins. But in addition to nutrients it can use, cells take in substances they can’t use or are actively toxic. Redox [reduction/oxidation] metabolism expels them in three phases, first by changing their electronic charge (oxidation), then making them water soluble, and then finally expelling and excreting them — housekeeping.

Elements, enzymes, amino acids, proteins, cells, respiration, energy, oxidation = life.