Question

Assertion :Gram negative bacteria do not retain the stain, when washed with alcohol. Reason: The outer membrane of Gram negative (-ve) bacteria contain lipopolysaccharides, a part of which is intergrated into membrane lipid.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Both Assertion and Reason are incorrect.

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

When a decolourizer, such as alcohol or acetone is added, it interacts with the lipids of the cell membrane. A Gram-negative cell loses its outer lipopolysaccharide membrane and the inner peptidoglycan layer is left exposed. The crystal violet complexes are washed from the Gram-negative cell along with the outer membrane.