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Difference Between Polar and Nonpolar Amino Acids

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Polar and Non-Polar are two types of Amino Acids. Amino acids are organic compounds that are the building blocks of proteins. They contain both an amino group (-NH2) and a carboxyl group (-COOH) attached to the same carbon atom, known as the alpha carbon. The remaining side chain or R-group is what distinguishes one amino acid from another and determines its specific properties and functions.

What is Polar Amino Acids?

Polar amino acids are one of the classifications of amino acids based on their chemical properties. These amino acids have a partial positive and negative charge, which makes them hydrophilic (water-loving). This polarity arises due to the presence of functional groups, such as -OH (hydroxyl), -NH2 (amino), -COOH (carboxyl), or -SH (sulfhydryl), in their side chains.

What is Non-Polar Amino Acids?

Nonpolar amino acids are one of the classifications of amino acids based on their chemical properties. These amino acids do not have a charge and are hydrophobic (water-fearing). The nonpolarity arises due to the presence of nonpolar side chains or R-groups, such as methyl or ethyl groups.

Also Read: Protein

Difference Between Polar and Nonpolar Amino Acids

Characteristics                      

Polar Amino Acids

Non-Polar Amino Acids

Charge Can be positively charged, negatively charged, or neutral Neutral in charge
Hydrogen Bonding Can form hydrogen bonds with polar molecules, including water and other polar amino acids Cannot form hydrogen bonds with polar molecules
Solubility Generally soluble in water Generally insoluble in water
Location in Proteins Often found on the surface of proteins Often buried in the interior of proteins
Reactivity  More reactive due to their hydrophilic nature Less reactive due to their hydrophobic nature
Specific examples Serine, threonine, asparagine, lysine, arginine, glutamine, aspartic acid Alanine, valine, leucine, isoleucine, phenylalanine, tryptophan, methionine
Function in proteins Often involved in protein-protein interactions, enzymatic reactions, and ligand binding Often involved in maintaining the stability of protein structures

FAQs on Polar and Non-Polar Amino Acids

Q1: What are the 20 standard amino acids?

Answer: 

The 20 standard amino acids are alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine.

Q2: What is the difference between essential and non-essential amino acids?

Answer: 

Essential amino acids cannot be produced by the human body and must be obtained through the diet, while non-essential amino acids can be synthesized by the body.

Q3: What are some functions of amino acids in the body?

Answer:

Amino acids are used as building blocks to synthesize proteins, but they also have other important functions in the body. Some amino acids are used as a source of energy, while others are involved in the synthesis of important biomolecules like neurotransmitters, nucleotides, and hormones.

Q4: What is the difference between an acidic and a basic amino acid?

Answer:

An acidic amino acid has a negatively charged side chain at physiological pH, while a basic amino acid has a positively charged side chain at physiological pH.


Last Updated : 18 Apr, 2023
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