Lipids Flashcards
(32 cards)
what are three functions of biomembranes?
- barrier between cell and environment
- communication
- boundaries for organelles
what is the definition of a phospholipid bilayer?
is an energetically favourable element
what does energetically favourable mean?
lowest free energy
what is structure of phospholipids
heads and tails groups
what are the headgroups?
polar and hydrophilic
hydrogen bonding to water and electrostatic interactions with counter ions
what are the tailgroups?
apolar and hydrophobic
van der waal forces
describe the phospholipids relationship with high and low temperatures…
high temperatures:
fluid phase and movement allowed (liquid crystalline state)
low temperatures:
gel like phase, tightly packed hydrocarbons
what is a descriptor of ALL lipid classes?
amphipathic (polar and non-polar elements present)
what is the simple structure of a fatty acid?
alkyl chains terminated by carboxylic acid groups
what does ‘saturated’ mean for fatty acids?
indicates chain fully reduced
no double bonds within the alkyl portions
what are structural consequences of unsaturation of fatty acids?
bend more easily and packed less tightly
due to cis double bonds
effects melting points
what types of fatty acids decrease transition temperature?
short chain fatty acids and unsaturated fatty acids
how do polar bears produce energy?
burn fatty acid via beta-oxidation
what are the two main types of phospholipids?
phosphoglycerides
phosphoceramides
what is the structura; components of phosphoglycerides?
glycerol backbone
phosphodiester (in place of glcerol)
alcohol headgroup
two ester linked fatty acids
what are the two pathways in kennedy pathway, and their products?
choline = pc ethanolamine = pe
what is Phosphatidylinositol?
key membrane constituent and participant in essential metabolic processes
what is cardiolipin?
diphosphatidylglycerol
dimeric structure
four acyl groups and 2 negative charges
in membranes of bacteria and mitochondria
what are waxes
esters of longchain alcohols with long chain fatty acids
what are terpenes?
lipids formed from multiple isoprene units
steroids
flovourings
what are the 4 functions of cholesterol?
regulatory
cellular signalling
building block of membranes
modulate fluidity
what does cholesterol prevent in the membrane?
crystalisation of hydrocarbons and phase shifts
what are 5 molecules that cholesterol is a precursor for?
steroids vitamin d bile acids corticosteroids sex hormones
describe the plasma membrane assymetry
outer leaf
inner leaf
lipid rafts
