lipids⭐️ Flashcards
what does saturated mean?
there are no c=c double bonds and the molecule has as many hydrogen atoms as possible
what does unsaturated mean?
there is at least one c=c double bond therefore contains fewer hydrogen atoms than is maximally possible
what is a triglyceride?
formed by the joining of one molecule of glycerol to three fatty acids through three condensation reactions, forming ester bonds
what are the characteristics of lipids?
soluble in organic solvents, insoluble in water, all have C. H and O
what are the roles of lipids?
source of energy- when oxidised, lipids release twice the amount of energy as the same mass of carbohydrate.
waterproofing- insoluble in water so provides waterproofing in plants and animals.
insulation- slow conductor of heat so reduced heat loss. electrical insulator for myelin sheath (nerves)
protection- around organs
what are the role of triglycerides?
key role in respiration and energy source due to its insolubility and high carbon to hydrogen ratio
what is a phospholipid?
a glycerol with two fatty acids and one phosphate group binded to it, joined via a condensation reaction
what is the role of phospholipids?
create a phospholipid bilayer in cell membranes as the hydrophobic tails and hydrophilic heads allow them to arrange themselves away from the direction of the water
what are the properties of triglycerides?
low mass to energy ratio- good storage molecules because much energy can be stored in a small volume.
high ratio of energy storing carbon-hydrogen bonds to carbon atoms- excellent source of energy.
large, non polar molecule so insoluble in water- doesnt affect osmosis in cells or water potential
high ratio of hydrogen to oxygen atoms so release water when oxidised- provide a source of water to desert animals
name the group represented by COOH
carboxylic acid
describe the test for the presence of lipid in a liquid food sample
dissolve the sample in water. add ethanol and shake to dissolve. white milky emulsion
explain the arrangement of phospholipids in the cell surface membrane
phospholipids are polar molecules, fatty acid tail repels the water, meaning its hydrophobic, and phospholipid heads are hydrophilic, so attract water, therefore create a bilayer
whats the function of phospholipids?
they form a hydrophobic barrier around cells, polar phospholipids arrange themselves into a bilayer.
they are also responsible for cell recognition, the phospholipid heads combine with carbohydrates to form glycolipids
What is the structure of a triglyceride?
Triglycerides are made from a glycerol molecule and three fatty acids. The fatty acids form ester bonds with the glycerol through condensation reactions. Fatty acids vary in length and whether they have double bonds between carbon atoms (unsaturated) or not (saturated)
How does the structure of a triglyceride effect its function?
- source of energy due to many carbon - hydrogen bonds
- storgae due to low mass to energy ratio
- do not affect osmosis due to large, insoluble nature
- source of water due to high number of hydrogen to oxygen atoms which can release water when oxidised