Question

What is DNA?

Answer 1

Hint: The offspring acquire the characters of the parents. The siblings often have similar eye colour or hair or complexion. The DNA is responsible for the similar characteristics in a family. It passes from one generation to another.

Complete answer:
DNA stands for deoxyribonucleic acid. It is the unit of heredity. The genetic material is transferred over generations through DNA. The DNA is found in the nucleus of the cell. The chromosomes contain the DNA. The strands of the DNA are coiled around the histone proteins which give a beaded like appearance. It plays an important role in cell division.

Structure of DNA:
Eukaryotic DNA is a double stranded linear structure which looks like a double helix. It is made up of three main components- deoxyribose sugar, nitrogenous bases like adenine, guanine, cytosine, thymine and phosphate backbone. The two nucleotides are linked together by phosphor diester bonds. One stand of the DNA is exactly complementary to the other. Both the stands are linked together by the covalent bonds present between the complementary nucleotides present in each stand. Adenine forms bonds with thymine and cytosine with guanine.

Function of DNA:
1)DNA carries genetic information from one generation to another.
2)DNA is important for protein synthesis.
3)DNA is also important for the cell division.

Note: In prokaryotic cells, the circular DNA is present in the cytoplasm. In the eukaryotic cell, the DNA is present in the circular form in the organelles like chloroplast and mitochondria. Chloroplast and mitochondria can thus synthesise their own proteins required for functioning.