Biomolecules | Amino acids(Part-1) zwitter ions for CSIR-NET GATE IIT-JAM BARC 2019

Introduction

This tutorial focuses on understanding amino acids, specifically zwitter ions, as presented in the video "Biomolecules | Amino acids(Part-1)." This knowledge is crucial for students preparing for competitive exams like CSIR-NET, GATE, IIT-JAM, and BARC. By breaking down the concepts into manageable steps, you will gain a clearer understanding of amino acids and their properties.

Step 1: Understand the Basics of Amino Acids

• Amino acids are the building blocks of proteins and play a vital role in biological processes.
• Each amino acid contains a central carbon atom, an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable R group (side chain).
• The R group determines the unique characteristics of each amino acid.

Practical Tip

Familiarize yourself with the 20 standard amino acids and their properties, as this will help you in recognizing their functions in proteins.

Step 2: Explore the Concept of Zwitter Ions

• Zwitter ions are molecules that have both positive and negative charges but are overall neutral.
• In the case of amino acids, zwitter ions form when the amino group is protonated (-NH3+) and the carboxyl group is deprotonated (-COO-).
• This occurs at a specific pH known as the isoelectric point (pI).

Common Pitfall

Remember that not all amino acids exist as zwitter ions at all pH levels. Understanding the pH's effect on amino acid structure is crucial.

Step 3: Determine the Isoelectric Point

• The isoelectric point is the pH at which an amino acid has no net charge.
• To calculate the pI for an amino acid, use the formula:
  • pI = (pKa1 + pKa2) / 2
• pKa1 refers to the carboxyl group, and pKa2 refers to the amino group.

Example Calculation

For a simple amino acid like glycine:

• pKa1 (carboxyl group) = 2.34
• pKa2 (amino group) = 9.60
• pI = (2.34 + 9.60) / 2 = 5.97

Step 4: Applications of Zwitter Ions

• Zwitter ions play a significant role in biological systems, especially in enzyme activity and protein folding.
• Understanding zwitter ions can also help in protein purification techniques such as isoelectric focusing.

Practical Tip

Consider how the zwitter ion form of amino acids affects their solubility and interaction in biochemical reactions.

Conclusion

In this tutorial, you have learned about the fundamental aspects of amino acids and the unique properties of zwitter ions. Understanding the structure, the isoelectric point, and the applications of these concepts is essential for further studies in biochemistry and molecular biology. As a next step, explore the second part of this series to deepen your knowledge of biomolecules.