Micelles - Stable ball-like structures in the water, hydrophilic tails project inwards away from the water Fluid mosaic model Fluid - Phospholipids move sideways Mosaic - Pattern produced by the scattered protein molecules Fluidity depends on: Unsaturated ↑, fluid ↑ Longer the tail, fluid ↓ Temperature ↓, fluid ↓ When temperature decreases, cholesterol intercalates between phospholipid and prevents them from moving around Ion transportation Unable to pass through the hydrophobic core of the phospholipid bilayer. Lined with amino acids with hydrophilic R group Aquaporin Water is polar, so it is unable to pass through the hydrophobic part of the phospholipid tail. Channel proteins are hydrophilic Aqauporins increase permeability of membrane to water Roles of the components of cell membrane Phospholipids Forms a barrier to charged particles Can modify chemically to act as signalling molecules Activate other enzymes C
A catalyst: substance which speeds up the rate of a reaction without itself undergoing permanent change. Enzymes Globular proteins Increase the rate of reaction Enzyme-substrate complex Lock and key theory The substrate molecule is held within the active site by bonds that temporarily form between the R groups of the amino acids of active site and substrate molecules Induced fit mechanism Substrate shape is not exactly complementary to the shape of the active site Active site changes its shape slightly when substrate binds This allows them to fit better Forms enzyme-substrate complex Products leave Lysozyme is a natural defence against bacteria (peptidoglycan/ murein cell wall) that is found in tears, saliva Activation energy An enzyme requires lower activation energy compared to without enzyme When a chemical reaction takes palce, bonds within the reactants are broken and new bonds are made to form products Breaking bonds require