GCSE Enzymes Key Words

Active Site

The part of an enzyme with a unique shape where a specific substrate fits during an enzyme-catalysed reaction

Amino Acid

A monomer that is the building block for proteins

Amylase

An enzyme that catalyses the breakdown reaction of starch into simple sugars

Buffer solution

A solution that is used to produce a particular pH and will

maintain this pH if acids or alkalis are added

Carbohydrase

An enzyme that catalyses the breakdown reaction of

carbohydrates into simple sugars

Catalyst

A substance that increases the rate of a chemical reaction

without changing chemically themselves

Complex carbohydrate

A molecule that is made of a chain of simple sugars bonded

together e.g. starch

Denature

To change the shape of an enzyme’s active site, this may occur

due to high temperatures or extremes of pH. Denatured

enzymes no longer work

Enzyme

A protein produced by a living organism that speeds up the rate of a biological reaction without being used up or changed in the process (biological catalyst)

Enzyme-substrate complex

An enzyme and substrate joined together

Glucose

A simple sugar used by cells for respiration

Induced fit model

The model which involves the active site of an enzyme changing shape to better fit the substrate after the substrate binds

Iodine Solution

An orange solution that turns blue-black in the presence of starch

Lipase

An enzyme that catalyses the breakdown reaction of lipids into glycerol and fatty acids

Lipids

Molecules of fats/oil, made of glycerol and fatty acids

Lock and key hypothesis

The model which compares the specificity of enzymes with a key and its lock

Metabolism

All the chemical reactions in the cells of an organism

Neutralise

To make an acidic or alkaline solution turn neutral (pH 7)

Optimum

The best or most appropriate - for instance, the conditions under which an enzyme works best (e.g. temperature and pH)

pH

Scale of acidity or alkalinity. A pH (power of hydrogen) value below 7 is acidic, a pH value above 7 is alkaline

Protease

An enzyme that catalyses the breakdown reaction of proteins into amino acids

Protein

A molecule made up of chains of amino acids

Rate of reaction

A measure of how quickly a chemical reaction occurs

Simple sugars

A carbohydrate that only contain one or two sugar units

Specific

A particular requirement. An enzyme is specific to its substrate and will not work with other substrates

Substrate

The substance on which enzymes act. It binds to the active site; a reaction is then catalysed by an enzyme

Starch

A complex, insoluble carbohydrate, used by plants to store glucose