Lipids Flashcards
where do lipids occur ?
occur in mammals as fats and n plants as oils
what are the two types of lipids ?
triglycerides and phospholipid
what are triglycerides composed of ?
condensations reactions between one glycerol molecule and 3 fatty acids
what is the bond formed between glycerol and fatty acid ?
ester bond
what are the two types of fatty acid ?
saturated lipids and unsaturated lipids
where are saturated lipids found ?
animal fats
saturated lipids contain ..
hydrocarbon chain has only single bonds between carbon atoms
where are unsaturated found ?
plants
unsaturated lipids consists ..
of hydrocarbon chain with at least one double bond between carbons
why does unsaturated lipids have a lower melting point ?
intermolecular forces are weaker
What state are the two types of lipids at room temperature ?
saturated lipids - solid
unsaturated lipids - liquid
Properties of Triglycerides
- large ratios of energy storing carbon hydrogen bonds a lot of energy is stored
- act as a metabolic water source, release water if they are oxidised
- do not affect water potentials and osmosis, large and hydrophobic - insoluble in water
- low mass so stored without increasing the mass and preventing movement
What are the roles of lipids in living organisms ?
- energy storage
- waterproofing
- insulation
- electrical insulation
Energy storage
- triglycerides are oxidised during respiration so energy is released
- some is lost to the environment as heat to make ATP
- fat store - endure seasons
Waterproofing
- repel water - hydrophobic
- sebaceous glands act as a water repellent
Insulation
- lipids are poor conductors
- restricted blood supply so little body heat is distributed to the fat under the skin
where are triglycerides stored in mammals ?
adipose tissue - subcutaneous tissue
Where is myelin found ?
surface membranes if cells that wrap around the long fibres of nerve cells in animals
many fibres insulate fibre to ..
prevent the passage of sodium and potassium ions
what is phospholipid composed of
two fatty acids and a phosphate group and glycerol
structure of phospholipids
- hydrophilic head due to negative charge on phosphate group
- attracts water and repels fats as it is charged
- the fatty acid chain is not charged - hydrophobic tail and it repels water but will mix with fats
properties of phospholipids
- have two charged regions so they are polar
- in water, they are positioned so that the heads are exposed to water and the tails are not
- forms a phospholipid bilayer membrane structure which makes up the plasma membrane around cells
