Lipids Flashcards
Why are unsaturated fats liquid
They have a weaker structure due to kink made by double bond, so cant pack tightly resulting in lower melting point
Difference between triglyceride and phospholipid
it has 2 fatty acids and a phosphate attached to the glycerol instead of 3 fatty acids
what bond is formed between the glycerol and phosphoric acid
phosphoester bond by condensation reaction
why is the head of the phospholipid polar
it has a negative charge meaning charge is unevenly distributed therefore is polar and hydrophillic
why is the tail of the phospholipid non polar
it is a chain of carbon hydrogen atoms, making it hydrophobic as it is non polar
amphipathic
when it has both hydrophobic and hyrophillic
micelles
sphere of phospholipids with the hydrophilic head on the outside and hydrophobic head on the inside
what is a phospholipid bilayer
basis of cell membranes made from two layers of lipid molecules, with the hydrophobic tails buried on the interior of the membrane
function of phospholipid bilayer and why its stable
they can move past each other, keeping membrane fluid to change cell shape
-due to tail being inside the membrane is stable
why is the phospholipid bilayer an electrical insulator
it prevents ions entering and leaving, as ions dissolved in water cannot enter so only small non polar molecules like o2 and co2 can diffuse in and out- membrane potential kept in equillibrium
function of phospholipid bilayer
acts as a barrier to separate the inside of a cell from its outside environment
cholesterol
-4 ring structure of carbon
-contains cho
-doesnt contain glycerol or fatty acids
-small molecule
-hydrophobic and hydrophillic molecule
role of cholesterol
regulates the fluidity of the membrane, preventing it from becoming too stiff or fluid (at high temperatures, it stabilizes the membrane and raises its melting point and at low temp it prevents the phospholipids clustering together and stiffening)
what cholesterol forms
testosterone, oestrogen, vitamin D
why is cholestrol used as hormones
theyre small and amphipathic so they can pass through the hydrophobic part of the membrane
what happens when cholesterol is injested
abundant in plants and on injestion can be converted into animal hormones
what is the bond called between a fatty acid and glycerol
ester linkage
saturated trigylceride
c-c
unsaturated trigylceride
c=c
saturated fatty acids
one straight chain
,mainly found in foods like solids
structure of unsaturated fatty acids
kink in chain due to double bond
in liquids like oil
role of lipids in insulation
-in myelin sheath in nerve cells(electrical insulator so moves further and faster)
-extra fat in animals before hibernation
-regulate body temp as break down of fat releases heat
role of lipids in buoyancy
-less dense than water so floats
-compacted less densely, occupying more space for same amount of molecules making it lighter
-sea animals can float
-less dense than muscle and bone
Lipids as an energy source
-double energy source as protien and carb
-95% of triglycerides are fats- energy
-broken down generating ATP
-circulate in blood stream to deliver cells energy
