Lipids Flashcards
name two main groups of lipids
- triglycerides
- phospholipids
what are the other groups of lipids?
- waxes
- steroids
name some shared characteristics of lipids
- contain carbon, hydrogen and oxygen
- smaller proportion of oxygen than in carbohydrates
- insoluble in water (no affinity)
- soluble in organic solvents - alcohol/acetone
role of lipids
- structural component of cell membranes
- weatherproofing
- organ protection
- insulation/ electrical insulation
- energy store
why are lipids good for weather proofing in plants?
no affinity for water
- conserve water
- prevents transpiration - waxy cuticle
what lipids are produced in mammals for weatherproofing?
oily secretion from sebaceous glands
how are lipids used for electrical insulation?
myelin sheath - prevent loss of impulses
why are lipids good for insulation?
poor conductors of heat
give two descriptions of triglycerides
- non-polar
- hydrophobic
why are saturated fatty acids solids at rtp?
- maximum number of hydrogen per bond
- same shape pack together
- compact
- solid
why are oils liquids at rtp?
- unsaturated so contains double bonds
- double bonds create kinks in structure due to different shapes
- less compact
- space between atoms so liquid
name four properties of triglycerides which link to structure
- good source of energy =high ratio of energy storing carbon-hydrogen bonds to carbon atoms
- storage = low mass to energy ratio - compact shape
- non-polar = doesn’t affect osmosis
- source of water = high ratio of hydrogen atoms to oxygen so release water when oxidised
what are phospholipids?
diglycerides
what do phospholipids consist of?
two fatty acids
glycerol
phosphate group
why are phospholipids described as polar?
hydrophilic phosphate head with hydrophobic fatty acid tails
