lipids (unit 3) Flashcards
(24 cards)
what are lipids?
also known as macromolecules (large and complex) - contains , carbon, hydrogen and oxygen
are fats and oils - liquid at room temp
fats - solid at room temp
are lipids soluble on non-soluble in water?
they are non-polar meaning they are insoluble
what does non-polar mean?
no regions of partial positive or partial negative charge, so they aren’t electrostatically attracted to water molecules - in lipids the outer shell electrons are more evenly distributed hence this case
what are triglycerides
a lipid composed of one glycerol molecule and three fatty acids
what is glycerol?
alcohol found in triglycerides
what are fatty acids
long-chain carboxylic acids used in the formation of triglycerides
how are triglyceride’s formed?
hydroxyl groups interact forming three water molecules and bonds between the fatty acid and the glycerol molecule
what are the bonds called when triglycerides are formed?
ester bonds
how do you reverse the reaction and what is it called?!
hydrolysis reaction - and use three water molecules to break it down
what are saturated lipids?
fatty acid chains that contain no double bonds
what are unsaturated lipids
fatty acids with double bonds
why are unsaturated lipid’s usually oil?
because the double bonds cause the molecule to kink/bend meaning they can’t pack closely together therefore they’re liquid at room temperature
monounsaturated meaning
one double bond
polyunsaturated meaning
two or more double bonds
what are phospholipids
modified triglyceride’s - phosphorus, carbon, h2 and o2
how are phospholipids modified?
phosphate group replaces one fatty acid in the triglyceride
are phospholipids soluble or insoluble in water?
soluble in water as inorganic phosphate ions have extra electrons meaning it’s negatively charged - and have a non-polar tail - hydrophobic (the fatty acid) and charged end - hydrophobic (head - phosphate group)
hydrophobic
the physical property of a molecule that is repelled by water
hydrophilic
the physical property of a molecule that is attracted to water
how do phospholipids interact with water?
they form a layer on the surface of water (head/phosphate in the water and tail/fatty acids sticking out) - this creates a bilayer where the tail point towards the sheet centre and the heads surround them - helps form cell membranes as this separates cells’ aqueous environment from the aqueous cytosol
- also allows stability in plasma membranes
what are sterols
steroid alcohols - lipid but not fats or oils
- complex alcohol molecules with 4 carbon rings and a hydroxyl group at one end
- dual hydrophobic/hydrophilic characteristics
what is cholesterol
a type of sterol - comes from liver and intestine (also helps form cell membranes)
- it’s positioned between the phospholipids with the hydroxyl group at the outer membrane meaning it adds stability to cell membranes and regulates their fluidity by keeping them fluid at low temps and preventing excess fluidity at high temps
what is cholesterol useful for other than cell membranes?
vitamin D, bile, and steroid hormones are also made using cholesterol
some roles of lipids?
- membrane formation and hydrophobic barriers
- hormone production
- triglycerides have energy storage under skin eg thermal insulation for penguins and cushions vital organs
- waterproofing leaves and feathers
- electrical insulation for impulse transmission
