BIOLOGY 1A03 Study Guide - Final Guide: Respiratory Tract, Lipid Bilayer, Dental Plaque

• School: McMaster University
• Department: Biology
• Course: BIOLOGY 1A03
• Professor: Alastair Tracey Rosa Da Silva

Document Summary

Cell membranes: membranes separate an internal environment from the external environment, protect the cell from damaging toxins, allow entry of compounds, & metabolic waste disposal. Stacked lipid bilayer: the bilayer has a hydrophobic core and a peripheral (water loving) hydrophilic surfaces, cell membranes are thin (5-10nm) Fluidity: phospholipids are not stationary because membranes are fluid as they can move laterally within one layer of the lipid bilayer (left, right, forward, backward). kinks in hydrophobic tails that affect overall permeability: external environmental factors like temperature influence membrane permeability. Higher temperatures promote fluidity, while lower temperatures decrease fluidity. A bilipid membrane containing just phospholipids is too fluid. Cholesterol constrains fluidity by packing closely to neighboring phospholipids. At low temperatures, phospholipid bilayers behave like other fats; they solidify. Facilitated diffusion: uses transmembrane transport proteins embedded in the membrane, movement along a concentration gradient, no energy required.