Lipids and Membranes 3 Flashcards
What is the Golgi Apparatus?
The region in the cell where the final finishing touches to protein and lipid synthesis are made and where they are packaged up into vesicles and distributed.
What are oils and fats?
A group of chemical compounds that do not easily dissolve in water (essentially hydrocarbon chains).
How do we obtain a fatty acid?
By attaching a carboxyl group (-COOH) at the end of a hydrocarbon chain.
Describe the lipid self-assembly process.
When lipids are placed into an aqueous environment they minimise the free energy of the system by organising themselves such that the polar head groups are exposed to the water and the hydrophobic groups are shielded.
Which properties of lipids vary with lipid type?
The charge and size of head groups, and the length and number of hydrophobic tails.
Which properties determine the area of a lipid bilayer?
The type of head group (its steric, electrostatic effects) and the degree of unsaturation of the tails. Unsaturated tails (with a kink due to cis bond) take up more area than straight hydrocarbon tails.
Are most lipids in our bodies saturated or unsaturated?
Unsaturated
What is the myelin sheath and its function?
A layer of fat (lipids) and protein that forms around nerve cells and acts as a protective electrical insulator.
What are surfactants and their function?
Amphiphilic molecules with one acyl chain and small, highly polar head groups that lower the surface tension between two liquids, between a gas and a liquid, or between a liquid and a solid.
What makes surfactants good at their function?
The single acyl chain can insert into the oil phase easily without taking up much volume or lateral area. The high charge density and small size allows the number density to be high at the oil interface = solubilise.
Why is most of life in liquid form?
As it can be quickly adapted/tuned (unlike solids).
What is Gibbs free energy?
A thermodynamic potential that can be used to calculate the maximum amount of work that may be performed by a thermodynamically closed system at constant temperature and pressure.
What must happen to the value for Gibbs free energy, G, for a spontaneous reaction or process to occur?
A system that does work loses energy to its surroundings, thus a reduction in G (ΔG<0) is necessary for a spontaneous reaction or process.
What happens to the Gibbs free energy at equilibrium?
The Gibbs free energy reaches a minimum.
What is the typical effect of mixing liquids on entropy?
Mixing of liquids typically increases the entropy of the system. Ordered system turns into a disordered system.
