Biology Year 9

Enzyme

A protein molecule that acts as a biological catalyst, speeding up chemical reactions in living organisms.

Substrate

The specific molecule that an enzyme acts upon.

Active site

The part of the enzyme where the substrate binds and the reaction occurs.

Lock and key model

A model explaining enzyme specificity, where the shape of the active site fits only one specific substrate.

Denature

The process where extreme changes in temperature or pH distort an enzyme, making it inactive.

Optimal temperature and pH

The ranges at which enzymes function best.

Substrate concentration

The amount of substrate present that affects the reaction rate until the enzyme becomes saturated.

Enzyme concentration

The amount of enzyme present that influences the reaction rate.

Inhibitors

Molecules that block the active site of an enzyme, preventing substrate binding.

Salivary amylase

An enzyme found in saliva that breaks down starch into smaller sugars.

Pepsin

An enzyme in the stomach that breaks down proteins into smaller peptides.

Lactase

An enzyme in the small intestine that breaks down lactose.

Lipase

An enzyme found in the small intestine and liver that breaks down fats into fatty acids.

Active transport

The movement of particles from low concentration to high concentration, requiring energy.

Diffusion

The movement of particles from high concentration to low concentration without the need for energy.

Concentration gradient

The gradual change in concentration of solutes in a solution as a function of distance.

Cell membrane

A biological membrane that separates and protects the interior of a cell from the external environment.

Passive process

A process that occurs naturally without the need for energy.

Examples of diffusion

Oxygen moving from the lungs into the blood; perfume scent spreading in a room.

Examples of active transport

Root hair cells absorbing mineral ions from soil into the plant cell.

ATP

Adenosine triphosphate, the energy currency of the cell used in active transport.

Reaction rate

The speed at which a chemical reaction occurs.

Specificity

The ability of an enzyme to selectively bind to a particular substrate.

Catalysts

Substances that speed up chemical reactions without being consumed.

Biological catalysts

Enzymes that facilitate biochemical reactions in living organisms.

Peptides

Short chains of amino acids formed during the breakdown of proteins.

Fatty acids

Building blocks of fats that are created when lipase breaks down fats.