Question

glycerol
fatty acids
triglyceride molecule
figure 12:

1. figure 12 above shows the formation of a triglyceride (aka lipid aka fat) from three fatty acid monomers and a glycerol. what elements are present in a lipid? do lipids follow the 1:2:1 ratio of c, h, o that carbohydrates have?

1. in figure 12, what is being removed to create the bonds to form the triglyceride? is this a hydrolysis or dehydration synthesis reaction?

1. what does \hydro\ mean? what does \phobia\ mean? if lipids are \hydrophobic,\ write a definition for what you think this means.

Explanation:

Question 1

Lipids (triglycerides) are formed from glycerol and fatty acids. Glycerol has C, H, O, and fatty acids have C, H, O (in their carboxyl group and hydrocarbon chain). So lipids contain carbon (C), hydrogen (H), and oxygen (O). Carbohydrates have a 1:2:1 ratio of C:H:O (e.g., \( \text{C}_6\text{H}_{12}\text{O}_6 \) for glucose). Lipids have a much lower proportion of O relative to C and H (e.g., a fatty acid like palmitic acid \( \text{C}_{16}\text{H}_{32}\text{O}_2 \) has a C:H:O ratio of 8:16:1, not 1:2:1), so they do not follow the 1:2:1 ratio.

When a triglyceride is formed from glycerol and fatty acids, a dehydration synthesis reaction occurs. In this reaction, a water molecule (\( \text{H}_2\text{O} \)) is removed for each bond formed between glycerol and a fatty acid. Hydrolysis is the reverse (adding water to break bonds), while dehydration synthesis removes water to form bonds (like in the formation of polymers from monomers, here triglyceride from glycerol and fatty acids).

• "Hydro" comes from Greek and means "water" (e.g., in "hydroelectric" related to water power).
• "Phobia" comes from Greek and means "fear" (e.g., "arachnophobia" is fear of spiders).
• If lipids are "hydrophobic", combining the meanings: "hydro" (water) + "phobic" (fear) → Lipids are "water - fearing", meaning they do not mix with water (are insoluble in water) and tend to repel or avoid water.

Answer:

Elements in a lipid: Carbon (C), Hydrogen (H), Oxygen (O).
Do lipids follow the 1:2:1 ratio of C, H, O (like carbohydrates)? No.

Question 2