What is the difference between a nucleoside and a nucleotide?

Nucleotide Nucleoside 1) The chemical composition of nucleotide consists of a phosphate group, a sugar and a nitrogenous base. 1) A nucleoside has a chemical composition that consists of a sugar and a base without the phosphate group. 2) Some of the major examples of nucleotides are adenosine, guanosine etc. 2) Some of the key examples of nucleosides are the same as nucleotides only with the addition of phosphate groups.

What are nucleic acids? Mention their two important functions.

Nucleic acids are biomolecules which are found in the nuclei of all living cells in the form of nucleoproteins or chromosomes (proteins containing nucleic acids as the prosthetic group). Nucleic acids are of two types : deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The two main functions of nucleic acids are : (i) DNA is responsible for transmission of hereditary effects from one generation to another. This is due to the daughter cells. (ii) DNA and RNA are responsible for synthesis of all proteins needed for the growth and maintenance of our body. Actually the proteins are synthesised by varies RNA molecules (y−RNA,m−RNA and t−RNA) in the cell but the message for the synthesis of a particular protein is given by DNA molecules.

What is glycogen? How is it different from starch?

Glycogen is a carbohydrate (polysaccharide). In animals, carbohydrates are stored as glycogen. When the body needs glucose, enzymes present in the body break glycogen down to glucose. Starch is a carbohydrate consisting of two components - amylose ( 15 - 20 % ) and amylopectin ( 80 - 85 % ) whereas glycogen consists of only one component whose structure is similar to amylopectin. Glycogen is more branched Amylopectin.