Question

Chromosome puffs are seen in
A. Lamp brush chromosomes
B. Polytene chromosomes
C. Somatic chromosomes of Drosophila
D. Both B and C

Answer 1

Hint: The presence of any swelling throughout the length of the chromosome is known as chromosome puffs. These swellings are known as puffs. These are the locations where active transcription takes place.

Complete answer:
Chromosome puffs are seen in somatic chromosomes of Drosophila as well as in polytene chromosomes. It is present as a diffused and uncoiled portion in a polytene chromosome, and in this region, the active process of transcription takes place. These are produced when the DNA replication takes place repeatedly with the absence of cell division, and hence, a large chromosome is formed. The polytene chromosomes possessing chromosome puffs are present in the salivary glands of Drosophila, also known as the fruit fly. This contains a large amount of mRNA. Thus, they are also known as salivary gland chromosomes. These chromosomes are responsible for the intense secretion happening in its larval stage.
i. Lamp brush chromosomes are those chromosomes that are active in transcription. These structures are absent in mammalian chromosomes. The name is due to its characteristic structure, which is formed in the diplotene stage of prophase I. This kind of chromosome is present in birds, insects and amphibians.
Hence, the correct answer is option D.

Note: Polytene chromosomes are found in both plants and animals. In plants, the presence is restricted to just ovaries and seed tissues which are immature. Other than Drosophila, many other organisms also possess polytene chromosomes. It is present in malpighian tubules and also in various protists.