Question

Which is responsible for the formation of nucleolus?

• A. SAT chromosome
• B. Nuclear membrane
• C. Endoplasmic reticulum
• D. Ribosomes

Answer 1

The correct option is A SAT chromosome

Secondary constrictions are narrow areas and are of two types - Joints and Nucleolar Organizing Region (NOR). Joints are areas involved in breaking and fusion of chromosome segments. NOR or nucleolar organizer region is secondary constriction capable of forming nucleolus in interphase. Satellite or trabant is knob-like part distal to NOR. The chromosomes with trabant are called as SAT-chromosomes. The satellite does not take stain and stains poorly.