Q- Write names of two special types of chromosomes describe any one of the with the help of diagram?

Answer:- 

There are special two types of chromosomes –

1.       Lampbrush chromosomes

 

2.       Polytene chromosomes

Polytene chromosomes –

• These special type of giant chromosomes. occur in the epithelial cells of intestine, fat bodies, malpighian tubules and salivary glands of larvae of many insects of the order – Diptera.

•  These chromosomes First of all discovered by E.G. Balbiani in 1881 in the Salivary gland of larva and Kostoff (1930) studied the important of these chromosomes. Due to their presence in salivary glands, they are known as salivary gland chromosomes.

• Structurally giant chromosomes consist of two types of transverse bonds which are known as chromatic (dark bands) & achromatic (interbands) respectively. 

• Dark bands contains more RNA and little amount of DNA. Several condensed and folded nuclei histones interbands, these fibres are present parallel to each other. 

• These bands spreads at some places to form special rings or swelling called puffs or balbiani rings. These rings are reversible.