Question

Would you expect an increase or a decrease of entropy to accompany the hydrolysis of phosphatidylcholine to the constituent parts (glycerol, two fatty acids, phosphoric acid, and choline)? Why?

Short answer

An increase in entropy is expected because the number of molecules increases, leading to greater disorder.

Step-by-step solution

Understand the concept of entropy

Entropy is a measure of the disorder or randomness in a system. In a chemical reaction, an increase in the number of molecules or a transition from a more ordered to a less ordered state generally leads to an increase in entropy.

Identify the reactants and products

The hydrolysis of phosphatidylcholine results in the following products: glycerol, two fatty acids, phosphoric acid, and choline. Initially, there is one molecule of phosphatidylcholine.

Compare the number of molecules

Initially, there is 1 molecule of phosphatidylcholine. After hydrolysis, there are 5 molecules (glycerol, two fatty acids, phosphoric acid, and choline).

Analyze the change in molecular structure

Breaking down a complex molecule (phosphatidylcholine) into simpler and more numerous components (glycerol, fatty acids, phosphoric acid, and choline) increases the overall disorder of the system.

Conclusion

Given that there is an increase in the number of molecules and the breakdown of a complex structure into simpler parts, the entropy of the system increases.

Key concepts

Phosphatidylcholine Hydrolysis

Phosphatidylcholine is a type of phospholipid or fat found in cell membranes. It's crucial for building cell membranes and facilitating cell signaling. Hydrolysis is a chemical breakdown process involving water. When phosphatidylcholine undergoes hydrolysis, it breaks down into simpler molecules: glycerol, two fatty acids, phosphoric acid, and choline. This reaction is significant in biochemistry because it's a common way cells degrade complex molecules to reuse their building blocks or to release energy. To visualize, imagine phosphatidylcholine as a lego structure being disassembled into individual lego pieces. Each smaller piece represents glycerol, fatty acids, phosphoric acid, and choline. Understanding this concept is essential to grasp how cells manage complex molecules.

Increase in Entropy

Entropy is a scientific term that measures disorder or randomness within a system. In simpler terms, it's a way to gauge how spread out and unpredictable the parts of a system are. When phosphatidylcholine hydrolyzes, it goes from being one organized, larger molecule to five smaller molecules. This shift results in increased entropy. Think of it as cleaning your room: starting with everything in one place (low entropy) versus spreading everything out across the floor (high entropy). In biochemical reactions like the hydrolysis of phosphatidylcholine, the increase in the number of molecules means an increase in entropy. This is because there's more randomness and less organization when there are more parts to deal with.

Molecular Breakdown

The term molecular breakdown refers to the process of splitting a complex molecule into simpler components. In the case of phosphatidylcholine hydrolysis, molecular breakdown involves converting a single molecule of phosphatidylcholine into five smaller molecules: glycerol, two fatty acids, phosphoric acid, and choline.

This breakdown takes place as the larger molecule reacts with water, resulting in severed chemical bonds and the creation of new, smaller molecules. This process is typical in biological systems where complex molecules need to be broken down for various purposes, such as energy production or material recycling. For example:

• Releasing stored energy from large molecules
• Providing building blocks for new molecules

An easy analogy is watching a complex LEGO structure disassemble into its individual bricks. Each brick represents a simpler molecule derived from the original complex structure, increasing disorder and scattering parts in the system.