Factors Affecting Membrane Structure PDF

Preview

Summary

Notes on Factors Affecting Membrane Structure Biology A Level OCR A...

Description

Factors Affecting Membrane Structure Membrane fluidity  It is important that a cell membrane maintains its fluidity otherwise the cell would not be able to function.  A fluid membrane is needed for many processes, such as for: o the diffusion of substances across the membrane o membranes to fuse, e.g a vesicle fusing with the cell membrane during exocytosis o cells to move and change shape, e.g macrophages during phagocytosis. Effect of Heat  As temperature increases the kinetic energy of the phospholipids increases  This creates gaps between the bilayer  Molecules can pass through the gaps, the permeability of the membrane increases Effects of Solvents  Water is a polar molecule and is important in creating membrane stability with the phospholipids  Other solvents like alcohols are less polar or benzene which is not polar  This can move into the bilayer disputing the structure Temperatures below freezing  The phospholipids don't have much energy, so they can’t move very much  They are packed closely together forming a rigid layer  Channel proteins and carrier proteins denature  Ice crystals may pierce the membranes and this would increase the permeable significantly

Temperatures between 0 & 45°C  The phospholipids can move around and aren't packed closely together  The membrane is partially permeable  Temperature gives the lipids more energy  This INCREASES PERMIABILITY Temperatures above 45°C  The phospholipids bilayer starts to melt and become more permeable  Water inside the cell puts pressure on the membranes  Channel proteins and carrier proteins denature increasing permeability...