Enzymes are 'biological catalysts*' - meaning they speed up chemical reactions in living things.
"Without enzymes, our guts would take weeks and weeks to digest our food, our muscles, nerves and bones would not work properly and so on - we would not be living!"

*catalyst: a substance which makes a chemical reaction go faster (without changing itself). A catalyst can be used over and over again without getting used up


Active site is basically where the substrate combins with the enzyme and where the catalyst (the sped up reaction) occurs.
http://academic.brooklyn.cuny.edu/biology/bio4fv/page/active_.htm <-- there is a really good animation on this link which describes what active site is.

Diagrams like this are often called 'lock and key models' because of the way the substrate fits into the enzyme.

Without enzymes, why would so many reactions be so slow?
Enzymes are an absolute necessity to live. Without enzymes, you wouldn't be able to breathe, swallow, drink, eat, or digest your food.

"The catalysts of biochemical reactions are enzymes and are responsible for bringing about almost all of the chemical reactions in living organisms. Without enzymes, these reactions take place at a rate far too slow for the pace of metabolism."

  1. Enzymes are highly specific in terms of what they act upon and what they do.
  2. This specificity and what the enzyme does is made possible by their structures
Enzymes make it easier for a reaction to take place.
Enzyme substrate will bind to a special area of the enzyme
called the active site
Enzymes are very specific to with reaction they catalyze and also the substrates which are involved in the reactions. They specify because of the substrate and the reaction. They can only catalyze the transformation of a specific group of substrates which all have either the exact of similar structure.
An example of specificity: The characteristics of the enzymes of hydrophilic and hydrophobic layers allow the plasma membrane to form. Enzymes specificity is responsible for creating shapes that complementary.
For complementary shapes, think of it as a handshake model (what was formerly called the lock & key model). The specific shapes allow the objects to function.
+ Video of the lock and key model
+ There are four types of specificity:
Absolute specificity, linkage specificity, group specificity and stereochemical specificity.
A substance, usually used in small amounts relative to the reactants, that modifies and increases the rate of a reaction without being consumed in the process.
Substrate: The material or substance on which an enzyme acts.
+Such an interaction would be structurally incorrect. Each enzyme has its own substrate (or set of substrates, which are closely related compounds with high structural similarity). Its specificity allows it to catalyze certain reactions with similarities.
Enzyme pepsin and enzymes on the membrane of mitochondria:
The enzymes on the membrane of the mitochondria (located in the inner membrane) make ATP.
Enzyme pepsin are released by cells in the stomach (and the small intestines) which are responsible for breaking down food proteins into peptides. Pepsin degrade proteins into polypeptides, which are then broken down into amino acids, dipeptides and tripeptides.