Lecture 4 Flashcards
5 things that a cell must do…
Generate required energy Manufacture cellular materials Obtain raw materials Remove waste Control mechanisms
Functions occur … within the cel
Simultaneously
Each process requires…
Specific conditions
Purpose of organelles
Provide special conditions, keep incompatible processes apart, allows concentration of specific molecules and formation of a conc. gradient, package substances for transport and export
Plasma membrane is….
Semipermeable
Hydrophobic…
Tails
Hydrophilic…
Heads
Composition of the fatty acids in membrane affects its…
Fluidity
Unsaturated tails are…
Kinky
Saturated tails…
Pack together
Unsaturated fatty acids make the membrane more or less fluid
More
Cholesterol is a…
fluidly buffer, resisting changes in membrane fluidity
At high temps cholesterol…
Stabilises lipid molecules so movement is restrictive
At low temps cholesterol…
Hinders close packing, lowering temp at which membrane solidifies
What controls movement of substances in and out of cell
Plasma membrane
Passive, occurs by conc gradient and brings organelles in equilibrium with surroundings, movement of hydrophobic molecules
Simple diffusion
Uses channels and carriers, movement of hydrophilic molecules
Facilitated diffusion
Uses energy, against conc gradient, allows difference between internal and external environments of the cell
Active transport
In directional, movement of one molecule actively to create a conc gradient to move another molecule
Co-transport
Role of membrane proteins
Transport Recognition Joining cytoskeleton to ECM Message relay/signalling Intercellular joining
