1.5 lipids Flashcards
what 4 characteristics do all lipids share?
- all contain C,H,O
- proportion of O:CH is smaller than in carbohydrates
- insoluble in water
- soluble in organic solvents e.g. alcohol and acetone
how do lipids contribute to the cell- surface membrane?
- phospholipids contribute to the flexibility
- transfer lipid- soluble substances across them
4 roles of lipids
- source of energy
- waterproofing
- insulation
- protection
what are the 2 main groups of lipids
phospholipids and triglycerides
why are lipids good at waterproofing?
not soluble in water
why are lipids a good source of energy?
when oxidised they release x2 amount of energy compared to the same mass of carbohydrate
why are lipids a good insulator?
slow conductors of heat
slow conductors of electricity
what is a saturated fatty acid?
all carbon- carbon single bonds
what is a mono-unsaturated fatty acid?
one carbon- carbon double bond
what is a polyunsaturated fatty acid?
more than one carbon- carbon double bond
draw a basic diagram of a triglyceride
see page 16
draw one molecule of glycerol
see page 16
what are triglycerides made up of?
3 fatty acid and 1 glycerol
what bond is formed when a fatty acid reacts with a glycerol molecule?
ester bond
why are fats made up of saturated fatty acids?
- no double bonds
- pack closely together
what state is fats at, at room temperature?
solids
what state is oils at, at room temperature?
liquid
why are triglycerides insoluble in water?
large and non- polar
why are triglycerides good storage molecules?
- low mass: energy ratio -> large energy can be stored in a small volume
- large -> doesn’t diffuse out of the cell
- insoluble-> doesn’t affect water potential
- high ratio of CH: C-> good source of energy
why is it important that triglycerides have a high hydrogen: oxygen ratio?
release water when oxidised so provides a source of energy
which part of a phospholipid is hydrophobic?
tail
which part of a phospholipid is hydrophilic?
head
why is it important that triglycerides have a high CH: C ratio?
excellent source of energy
draw the basic drawing diagram of phospholipids
see page 17
test for lipids
- add ethanol
- shake thoroughly
- add water
- shake gently
- cloudy- white precipitate
what are phospholipids made up of?
2 fatty acids, a glycerol and a phosphate
draw a more detailed diagram of phospholipid
see page 17
what 2 molecules form glycolipids?
phospholipids and carbohydrates
what are glycolipids involved in?
cell recognition
