Biology Revision Enzymes • Enzyme Activity Factors • Digestive System

Enzyme

Biological catalyst that speeds up reactions

Substrate

Molecule enzyme acts on

Active site

Part of enzyme where substrate fits

Enzyme-substrate complex

Formed when substrate binds to enzyme

Lock and key model

Substrate fits exactly into active site

Optimum temperature

Temperature enzyme works best at

Optimum pH

pH enzyme works best at

Low temperature

Reaction slower less collisions

High temperature

Enzyme denatures active site changes shape

Denature

Active site changes shape enzyme stops working

pH effect

Wrong pH denatures enzyme

Amylase

Breaks starch into sugars

Protease

Breaks proteins into amino acids

Lipase

Breaks lipids into fatty acids and glycerol

Digestive system

Organs that break down food

Mouth

Mechanical digestion and amylase released

Oesophagus

Tube moving food to stomach

Stomach

Churns food protease works acidic pH

Liver

Produces bile

Gallbladder

Stores bile

Bile

Neutralises acid increases pH for enzymes

Pancreas

Produces amylase protease lipase

Small intestine

Digestion completed nutrients absorbed

Large intestine

Water absorbed

Enzyme specificity

Each enzyme fits one substrate

Higher temperature more collisions

Faster reaction until optimum

Denatured enzyme

Substrate no longer fits active site