Nucleosides are the structural subunit of nucleic acids such as DNA and RNA. A nucleoside, composed of a nucleobase, is either a pyrimidine (cytosine, thymine or uracil) or a purine (adenine or guanine), a five carbon sugar which is either ribose or deoxyribose.

What is the basic structural difference between glucose and fructose?

Glucose is an aldehyde and whereas fructose is a ketone and has following structure according to Fischer projections. Another difference is the number of chiral carbons in glucose is 4 whereas in fructose is 3 . Also the number of 2 ° alcohol is 4 for glucose and 3 for fructose.

Write the product when D - glucose reacts with conc. HNO 3 .

When D - glucose react with concentrated Nitric acid, it forms Saccharic acid. In aqueous solution, the carboxyl group of an amino acid can lose a proton and the amino group can accept a proton to give a dipolar ion known as zwitter ion.

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.

Name an amino acid which is optically inactive.

For a compound to be optically active, it must be a chiral carbon having four different groups on the four valencies of carbon. Since glycine, the simplest amino acid has two different groups and two same group (hydrogen atom) on the valencies of carbon, hence it becomes an achiral molecule which cannot show optical rotation and hence is optically inactive. Therefore, glycine is optically inactive,