lipids Flashcards
what are some lipid characteristics
-insoluble in water
-contains carbon hydrogen and oxygen
-soluble in organic solvents like alcohol and acetone
lipid roles
-source of energy
-waterproofing
-insulation
-protection
how are lipids a source of energy
when oxidised lipids provide more than twice the energy as the same mass of carbohydrate and release valuable water
why are lipids good at waterproofing
insoluble in water
why are lipids good at insulating
fats are slow conductors of heat and when stored beneath the bodies surface help to retain body hear
what do lipids protect and how
fat is often stored around delicate organs to protect them (e.g. kidney)
what are triglycerides
three fatty acid chains attached to a glycerol held together by Esther bonds
why are triglycerides good storage molecules
low mass to energy ratio making them good storage molecules as much energy can be stored in a small volume
describe a saturated molecule
no double bonds between carbon atoms
describe a phospholipid structure
a phosphate attached to a glycerol which has two fatty acid chains attached to it
describe an unsaturated molecule
double bond between one or more molecules
what is special about phospholipids
they have a hydrophilic head and a hydrophobic tail
what is a property of a phospholipid
in an aqueous environment phospholipid molecules form a bilayer within cell surface membranes
what is the test used to test for lipids
emulsion test
what is the method for the emulsion test
1-add 2cm3 of the sample being tested to a test tube and add 5cm3 of ethanol
2-shake the test tube thoroughly
3-add 5cm3 of water and shake gently
4-a milky white emulsion indicates the presence of lipids
