Revision: Class 12 >> Biomolecules NEET (UG) Biomolecules

Carbohydrates that yield two to ten monosaccharide units, on hydrolysis, are called oligosaccharides.

In the hydrolysis of sucrose, there occurs a change in the sign of optical rotation from dextro (+) to laevo (−). The product so obtained is referred to as invert sugar.

Amino acids that cannot be synthesised in the human body and must be obtained through diet are known as essential amino acids.

An ∝-amino acid molecule contains both acidic carboxyl (-COOH) group as well as basic amino (-NH₂) group. Proton transfer from acidic group to basic group of amino acid forms a salt, which is a dipolar ion called zwitter ion.

Proteins may have one or more polypeptide chains. Each polypeptide in a protein has amino acids linked with each other in a specific sequence and it is this sequence of amino acids that is said to be the primary structure of that protein. Any change in this primary structure, i.e., the sequence of amino acids, creates a different protein.

Chemically, peptide linkage is an amide formed between the –COOH group and –NH₂ group. The reaction between two molecules of similar or different amino acids proceeds through the combination of the amino group of one molecule with the carboxyl group of the other. This results in the elimination of a water molecule and the formation of a peptide bond –CO–NH–. The product of the reaction is called a dipeptide because it is made up of two amino acids.

For example, when the carboxyl group of glycine combines with the amino group of alanine, we get a dipeptide, glycylalanine.

Denaturation is the process in which the secondary and tertiary structure of a protein is disrupted due to heat, a change in pH, or chemicals, while the primary structure remains unchanged. In denaturation, peptide bonds are not broken; only the weak bonds (like hydrogen bonds) are disturbed.

Hormones are chemical messengers created by the endocrine glands and transported through the bloodstream to govern body functions such as development, metabolism, reproduction and mood by interacting with specific target cells.

The repeating monomers in unbranched polymers of nucleic acids are called nucleotides.

A nucleotide is the fundamental unit of nucleic acids, which include DNA and RNA. A pentose sugar, a nitrogenous base, and a phosphoric acid group make up its three constituent parts.