pH is very important in biochemical systems because it affects almost every chemical process that occurs inside living organisms. Here’s a explanation:
1. Definition of pH
pH is a measure of how acidic or basic a solution is.
- It represents the concentration of hydrogen ions (H⁺).
- pH scale ranges from 0 to 14:
- pH < 7: Acidic
- pH = 7: Neutral
- pH > 7: Basic (alkaline)
2. Effect on Enzyme Activity
- Enzymes are proteins that work best only at a certain pH (called optimum pH).
- If the pH is too high or too low, enzymes can lose their shape and become inactive (denatured).
- Example:
- Pepsin in the stomach works best at pH 2 (acidic).
- Amylase in saliva works best at pH 7 (neutral).
3. Effect on Protein Structure
- Proteins have charged amino acids that depend on pH.
- Changes in pH can alter these charges, changing the protein’s shape and function.
4. Cellular and Metabolic Reactions
- Many biochemical reactions release or use hydrogen ions (H⁺).
- Correct pH ensures that these reactions proceed at the right rate.
- Example: Glycolysis and respiration require specific pH ranges to function properly.
5. Buffer Systems in the Body
- The body maintains pH using buffer systems that resist changes.
- Example:
- Blood pH is kept around 7.4 using the bicarbonate buffer system.
- Small changes can be harmful—blood pH below 7.0 or above 7.8 can be life-threatening.
6. Membrane Function and Transport
- pH affects the movement of ions and molecules across cell membranes.
- Proton gradients (differences in H⁺ concentration) are used to produce ATP in mitochondria.
7. DNA and RNA Stability
- Nucleic acids can be damaged or lose base-pairing ability at very high or low pH levels.
- Stable pH is essential for genetic information storage and expression.