Class 12 Chemistry simulations · Biomolecules

Amino acids as zwitterions

Change the pH and see how the charge on glycine changes; find its isoelectric point.

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What to notice

At the isoelectric point glycine exists mainly as a neutral zwitterion and does not move in an electric field.

Key relation

H₃N⁺–CH₂–COOH ⇌ H₃N⁺–CH₂–COO⁻ ⇌ H₂N–CH₂–COO⁻ ; pI = (pKₐ₁ + pKₐ₂)/2 = 5.97

Try this

Set pH = 2 and pH = 11. What is the net charge in each case?

What you can change

• pH: 0 to 14

More in Biomolecules

• Glucose: ring forms and mutarotation

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