Q.22 - Biology

Question

The muscle relaxes if no new nerve signal arrives. However the neurotransmitter from the previous stimulation is still present in the synapse. The activity of________ helps to remove this neurotransmitter.

a. myosin

b. action potential

c. tropomyosin

d. acetylcholinesterase

Step-by-Step Solution

Answer

The correct answer is (d) acetylcholinesterase 

The activity of acetylcholinesterase helps to remove this neurotransmitter. 

Step 1. Introduction

Muscle cells are specialized for contraction. Muscles allow for motions such as walking, and they also facilitate bodily processes such as respiration and digestion. The body contains three types of muscle tissue: skeletal muscle, cardiac muscle, and smooth muscle. 

Step 2. Explanation for the correct answer

d. acetylcholinesterase

• Acetylcholinesterase (AChE) is a cholinergic enzyme primarily found at postsynaptic neuromuscular junctions, especially in muscles and nerves. 
• It immediately breaks down or hydrolyzes acetylcholine (ACh), a naturally occurring neurotransmitter, into acetic acid and choline.

Step 3. Explanation for the incorrect answer

a. myosin

• Myosin is the prototype of a molecular motor—a protein that converts chemical energy in the form of ATP to mechanical energy, thus generating force and movement.

b. action potential

• An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. 

c. tropomyosin

• Tropomyosins are rod-like dimers which form head-to-tail polymers along the length of actin filaments and regulate the access of actin binding proteins to the filaments.