Question

Assertion (A): Ethidium bromide (EtBr) helps in visualizing DNA in UV light only
Reason (R): This intercalating agent absorbs light in range 500-700 nm

• A. Both A and R are true and R is the correct explanation of A
• B. A is true but R is false
• C. Both A and R are false
• D. Both A and R are true but R is not the correct explanation of A

Answer 1

The correct option is B A is true but R is false

Ethidium bromide (EtBr) is a stain used for visualizing DNA under UV light at about 260 or 300 nm. UV light ranges from 100-380 nm.

EtBr is an intercalating agent. DNA intercalators bind between adjacent base pairs of dsDNA, and are often used as fluorescent markers for DNA visualization.

EtBr (ethidium bromide) intercalates between DNA base pairs and bright orange bands of DNA can be seen in ethidium bromide-stained gel exposed to UV light.

Hence, A is true but R is false.