Lipids Flashcards
8 functions of lipids
electrical insulation
thermal insulation
cell membrane structure
energy store
waterproofing
source of metabolic water
buoyancy
protection
chemical elements of lipids
carbon, hydrogen, oxygen
solubility of lipids
insoluble in water
soluble in organic solvent (e.g. ethanol)
5 examples of lipids
triglycerides (all fats and oils)
phospholipids
waxes
steroids
cholesterol
lipids as electrical and thermal insulation
electrical: around neurons
thermal: adipose tissue under skin surface
lipids in cell membrane structure
phospholipid bilayer and cholesterol
lipids as an energy store
stored as droplets in the cytoplasm as they are compact and insoluble
have have a high energy yield –> 2x energy released compared to carbohydrates
lipids in waterproofing
leaf cuticles/fur/feathers/skin
lipids as a source of metabolic energy
can respire fats to release water
lipids in buoyancy
lipids are less dense than water so help with floating and swimming
lipids as protection
subcutaneous fat around major organs
simple lipids + e.g.
only glycerol and fatty acids –> triglycerides
compound lipids + e.g.
glycerol, fatty acids and a molecule, group or compound –> phospholipids
why are lipids not polymers?
they are made of monomers, but their monomers are not repeated, just joined
chemical formula and structure of glycerol
C3H8O3
3 carbons, each with a hydrogen and hydroxyl group. end carbons have 2 hydrogens
state and explain the chemical formula for a general fatty acid
CH3(CH2)nCOOH
CH3 and carboxyl group, with a variable group (R group) in the middle: any number of Cs bound to 2 Hs
ester bond
covalent bond between a fatty acid and glycerol.
saturated fatty acid
have a full complement of Hs in hydrocarbon tail –> no C=C in hydrocarbon tail.
higher melting point
solid at room temp
unsaturated fatty acid
don’t have full complement of H
have at least one C=C in hydrocarbon tail
lower melting point
liquid at room temp
polyunsaturated
more than one C=C in hydrocarbon tail
respiratory substrate
a molecule that can release energy to form ATP, which animals oxidise
oxidise
break down in the presence of oxygen
how is energy released from RS substrates?
from breaking C-C and C-H bonds
why can more energy be released for respiring lipids than carbohydrates?
lipids have many more C-C and C-H bonds (in their R group)
describe the structure of a tiglyceride
1 molecule of glycerol attached to three fatty acid tails joined by ester bonds
describe the structure of a phospholipid
1 molecule of glycerol with a phosphate group attached and 2 fatty acid tails joined to it by ester bonds
