B1.1.9 - Formation of Triglycerides and Phospholipids

What is the structure of a triglyceride?

one glycerol molecule bonded to 3 fatty acids via ester bonds

What is the structure of a phospholipid?

one glycerol molecule bonded to a phosphate group and 2 fatty acids bonded via 2 ester bonds

define an ester bond

A covalent chemical bond (C-O-C) formed through a condensation reaction b/w a carboxylic acid & an alcohol

What happens during the formation of an ester bond?

The carboxyl group of the fatty acid reactes with a hydroxyl on the glycerol, releasing a water molecule (-OH from fatty acid, H from glycerol) and creating an ester bond

Explain why triglycerides are entirely hydrophobic despite the presence of hydrophilic groups in fatty acid and glycerol molecules

The carboxyl group on the fatty acid and hydroxyl on the glycerol are the only hydrophlic parts of the molecules BUT are used in the condensation reaction

Why are phospholipids ampiphatic?

Their phosphate heads are hydrophilic + fatty acid tails are hydrophobic

How does the structure of phospholipids lead to the formation of cell membranes?

Phospholipids have a hydrophlic phosphate head that turn to face the aqeous environment + 2 hydrophobic fatty acid tails that are more attracted to each other → spontaneous formation of the lipid bilayer

State 3 similarities between triglycerides and phospholipids

• formed through condensation reactions (water molecules are produced)

• types of lipids/ glycerides

• has covalent ester bonds

Contrast 4 features of triglycerides and phospholipids

• triglyceride: glycerol, 3 fatty acids | 3 ester bonds | 3 water molecules released | hydrophobic

• phospholipid: glycerol, phosphate, 2 fatty acids | 2 ester bonds | 2 water molecules released | ampiphatic

Which trait dictates whether a triglyceride is an oil or a fat?

the type of fatty acids they contain (saturated or unsaturated)