Question 1

The structures of a glycerol molecule and a fatty acid molecule are shown below:

Glycerol:

H∣H−C−OH∣H−C−OH∣H−C−OH∣H\begin{array}{ccccc} & & \text{H} & & \\ & & | & & \\ \text{H} & - & \text{C} & - & \text{OH} \\ & & | & & \\ \text{H} & - & \text{C} & - & \text{OH} \\ & & | & & \\ \text{H} & - & \text{C} & - & \text{OH} \\ & & | & & \\ & & \text{H} & & \end{array}

Fatty Acid (Butyric Acid):

HHHO∣∣∣\//H−C−C−C−C∣∣∣\HHHOH\begin{array}{ccccccccc} \text{H} & & \text{H} & & \text{H} & & \text{O} & & \\ | & & | & & | & & \//& & \\ \text{H} - \text{C} & - & \text{C} & - & \text{C} & - & \text{C} & & \\ | & & | & & | & & \backslash & & \\ \text{H} & & \text{H} & & \text{H} & & & \text{OH} & \end{array}

Identify the specific atoms/functional groups from the fatty acid and the glycerol molecule that are removed to form water when they react to synthesize a lipid.
Name the covalent bond formed between a fatty acid and glycerol.
Name the type of reaction involved in forming this bond.

Table 1 shows information about three different 18-carbon fatty acids.

Table 1

Name of fatty acid	Number of carbon-carbon double bonds ( $C=C\text{C}=\text{C}$ )	Melting point ( $∘C^\circ\text{C}$ )
Stearic acid	0	70
Oleic acid	1	13
Linolenic acid	3	-11

Name the fatty acid from Table 1 that is a saturated fatty acid.
Use Table 1 to describe the relationship between the structure of a fatty acid and its melting point.

The ratio of saturated to unsaturated fatty acids in a cell-surface membrane determines the extent of the membrane's fluidity.

Scientists cultured the single-celled eukaryote Amoeba proteus in a liquid medium enriched with unsaturated fatty acids. They observed:

An increase in the proportion of membrane phospholipids containing unsaturated fatty acids.
A significantly higher rate of endocytosis (the process of engulfing extracellular nutrients).

Suggest and explain why there was an increase in the rate of endocytosis.