AOS 2

Key Terms :D

Enzyme

An organic molecule, typically a protein, that catalyses (speeds up) specific reactions

Catalyst

A substance capable of increasing the rate of a reaction without being used up

Catalyse

To increase the rate of a reaction

Substrate

A molecule that undergoes a transformation into a product with the use of a catalyst (enzymes)

Reactant

A molecule that undergoes a transformation into a product.

Product

The transformed molecule created in a reaction

Catabolic Reactions

Break down large molecules to smaller molecules

(Also Exergonic – energy ‘exits’)

Anabolic Reactions

Requires energy, builds larger molecules from smaller molecules

(Also Endergonic – energy ‘enters’)

Active Site

The part of an enzyme where the substrate binds

Enzyme-substrate complex

The structure formed when an enzyme and substrate are bound together.

Conformational change

Eg. A change in the shape of the active site of an enzyme to accomodate the substrate

Activation energy

The energy required to initiate a reaction

Collision theory

Explanation of chemical reactions: In order to react molecules must hit one another.

Denaturation

The disruption of a molecule’s external structure due to an external factor such as heat. This change is irreversible

Saturation point

The point at which a substance (e.g. an enzyme) cannot receive more of another substance (e.g. a substrate)

Limiting factor

A factor that prevents the rate of reaction from inreasing

Limiting Reagent

A reactant that prevents the rate of reaction from increasing.

Enzyme inhibitor

A molecule that binds to and prevents an enzyme from functioning

Competitive inhibition

The hindrance of an enzyme by blocking the active site and preventing the substrate from binding.

Non-competitive inhibition

The hindrance of an enzyme by binding to an allosteric site and changing the shape of the active site to prevent the substrate from binding.

Allosteric site 

A region on an enzyme that is not the active site.

Biochemical Pathway

A series of enzyme-catalysed biochemical reactions in which the product of one reaction becomes the substrate of the next reaction.

Co-factor

Any organic or inorganic molecule, such as a coenzyme or metal ion, that assists enzyme function

Co-enzyme

A non-protein organic cofactor that assists enzyme function. They release energy and are recycled during a reaction.