B1.1.8 & B1.1.9 Lipids - Fatty acids and triglycerides

lipids

a diverse group of substances in all living organisms, serving as mainly structural components of cell membranes, long-term energy storage, and signaling molecules

which solvents are lipids soluble and insoluble in?

• soluble in: non-polar solvents such as ethanol, toluene, and propanone (acetone)

• insoluble in: water - therefore hydrophobic/more attracted to non-polar substances

what are the melting points + structure of the different types of lipids?

• oils - melting point below 20°C, solidify at low temperatures

• fats - melting point between 20°C and 37°C, solid at room temp and liquid at body temp

• waxes - melting point above 37°C, solidify at high temperatures

• steroids - molecules with a characteristic four-ring structure

what are the building blocks of lipids?

glycerol and fatty acids - glycerol acts as backbone while 1-3 fatty acid hydrocarbon tails are attached

what links glycerol and fatty acids together?

covalent ester bonds that are formed through a condensation reaction between the hydroxyl group (-OH) of glycerol and the carboxyl (-COOH) group of a fatty acid

name the types of fatty acids and describe their structure

• saturated - fat molecules with no double bonds between carbon atoms in their chemical chain

• unsaturated - fat molecules with one or more double bonds between carbon atoms in their chemical chain

name the types of glycerides and describe their structure

• monoglycerides - fat molecules made up of a glycerol backbone attached to one fatty acid chain

• diglycerides - fat molecules made up of a glycerol backbone attached to two fatty acid chains (phospholipids)

• triglycerides - fat molecules made up of a glycerol backbone attached to three fatty acid chains

what is the key difference between steroids and glucose?

• steroids are connected at two points - in drawings they look stuck together

• glucose are only connected at one point

describe the process of how triglycerides are formed

1. each of the three fatty acids are attached to the glycerol by a condensation reaction

2. three molecules of water are produced - one for each bond

3. the bond between the fatty acids and glycerol backbone is an ester bond

4. bond is formed between carboxyl group on a fatty acid and hydroxyl group on the glycerol

5. these groups are the only hydrophilic parts of fatty acid.+ glycerol and because they’re used up in condensation, triglycerides are entirely hydrophobic

describe the structure of phospholipids

• similar structure to triglycerides with only 2 fatty acid tails

• phosphate group attached to glycerol backbone instead of the third fatty acid

• phosphate is hydrophilic, therefore phospholipids are amphipathic