Answer: A competitive inhibitor must fit the same active site as the substrate, requiring structural resemblance; an antagonist only needs to occupy a site (or alter the receptor's shape) that blocks activation, which does not require mimicking the natural messenger.
- A Antagonist drug molecules are said to rarely actually physically bind to their intended target receptor protein, regardless of dose, timing, or the particular tissue being studied in most textbook accounts during normal conditions as generally observed
- B A competitive inhibitor must fit the same active site as the substrate, requiring structural resemblance; an antagonist only needs to occupy a site (or alter the receptor's shape) that blocks activation, which does not require mimicking the natural messenger
- C Enzymes are said to possess no defined catalytic active site whatsoever, with mainly cell-surface receptor proteins actually having one, according to this particular claim as generally observed under usual circumstances according to most researchers
- D Receptors and enzymes are said to be largely similar chemically identical types of biological molecular targets in nearly every conceivable respect, down to the last atom in most cases according to standard textbooks in general practice
Correct answer: B. A competitive inhibitor must fit the same active site as the substrate, requiring structural resemblance; an antagonist only needs to occupy a site (or alter the receptor's shape) that blocks activation, which does not require mimicking the natural messenger
Explanation: Competitive inhibition specifically requires competing for the substrate's own binding site, so structural similarity to the substrate is what allows the inhibitor to fit there. An antagonist merely needs to block receptor activation, which can be achieved by binding a nearby site or altering the receptor's conformation allosterically, without resembling the natural messenger.
The hydrophobic hydrocarbon tail of each soap/detergent molecule dissolves into an oily dirt droplet, while the hydrophilic (ionic) head stays in the surrounding water - trapping the grease inside a micelle that rinses away with water.
Concept context
Drugs and how they interact with biological targets, chemicals in food, and cleansing agents (soaps and detergents) - chemistry applied directly to daily life and healthcare.