Question

A swelling in the band of a polytene chromosome is an indication of

• A. Gene action
• B. Gene inaction
• C. Mutation
• D. Gene damage

Answer 1

Answer: (A)

Gene action

A swelling in the band of a polytene chromosome is an indication of gene action. Polytene chromosomes are very large chromosomes. These are developed from the specialized cells which undergo many rounds of DNA replication without cell division forming a giant polytene chromosome. Polytene chromosomes are formed when replication produce many sister chromatids that remain synapsed together. Polytene cells have multiple copies of genes permits a high level of gene expression.

Thus, the correct answer is option A.