AS and A Level Biology 21 Views 1 Answers
State that triglycerides are non-polar hydrophobic molecules and describe the molecular structure of triglycerides with reference to fatty acids (saturated and unsaturated), glycerol and the formation of ester bonds
State that triglycerides are non-polar hydrophobic molecules and describe the molecular structure of triglycerides with reference to fatty acids (saturated and unsaturated), glycerol and the formation of ester bonds
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Triglycerides are non-polar, hydrophobic molecules, meaning they do not dissolve in water. This property makes them ideal for long-term energy storage in organisms.
Molecular Structure of Triglycerides
- Glycerol Backbone:
- A triglyceride molecule consists of a single glycerol molecule, which is a three-carbon alcohol with three hydroxyl (-OH) groups.
- Fatty Acids:
- Each of the three hydroxyl groups on the glycerol molecule can form a bond with a fatty acid. Fatty acids are long hydrocarbon chains with a carboxyl (-COOH) group at one end.
- Saturated Fatty Acids:
- Saturated fatty acids have no double bonds between the carbon atoms in their hydrocarbon chain, meaning each carbon is fully “saturated” with hydrogen atoms.
- They tend to have straight chains, allowing them to pack closely together, which makes them solid at room temperature (e.g., in animal fats like butter).
- Unsaturated Fatty Acids:
- Unsaturated fatty acids contain one or more double bonds in their carbon chain.
- The presence of a double bond introduces a kink in the chain, preventing tight packing. As a result, unsaturated fatty acids are often liquid at room temperature (e.g., in plant oils like olive oil).
- Formation of Ester Bonds:
- The formation of a triglyceride involves a condensation reaction between each hydroxyl group of glycerol and the carboxyl group of a fatty acid.
- In this reaction, a molecule of water is released, and an ester bond (-COO-) is formed between the glycerol and each fatty acid.
- This process is repeated three times, once for each fatty acid, resulting in a triglyceride with three ester bonds.
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