Question

Polytene chromosomes in salivary glands of Drosophila are formed as a result of

• A. Endoreplication
• B. Duplication without separation
• C. Replication of DNA without cell division
• D. All of the above

Answer 1

The correct option is D All of the above

Endoduplication is also called as polytenization which refers to absence of cell division after DNA replication which in turn causes multiplication of chromosome number of cells. Under normal conditions, DNA duplication in S-phase of cell cycle is followed by a series of events that lead to separation of duplicates DNA/chromosomes to the daughter cells; thereby resuming the original chromosome number. Polytene chromosomes in salivary glands of Drosophila are formed as a result of the replication of the chromosomes and the synapsis of homologues without cell division. It is known as endomitosis. Therefore all given options are correct.

Thus, the correct answer is option D.