Question

In polytene chromosomes, dark bands are visible. These bands are formed by the apposition of which one of the following?

• A. Protein particles
• B. Chromomeres on chromonemata
• C. Nucleosomes
• D. None of the above

Answer 1

The correct option is B Chromomeres on chromonemata

Polytene chromosomes are interphase chromosomes that consist of thousands of DNA strands. These giant chromosomes are characterized by interband morphology and are found in the two-winged flies and tissues of mammals as well as cells of the synergids, and endosperm of angiosperms. These are normal chromosomes which due to repeated rounds of DNA replication or endoreplication, become large. Under the light microscope, these chromosomes show distinct and alternating dark bands. The bands on these chromosomes are formed due to concentration of the chromatin. Regions of high concentrations are known as chromomeres (bands), and regions with low concentrations are known as inter chromomeres (interbands).

So, the correct answer is 'Chromomeres on chromonemata'