NEETBotanyCell - The Unit of Life
A dense, granular cell organelle was first observed by George Palade under the electron microscope in 1953. Which of the following statements correctly describes the nature of this organelle?
Options
- AIt is composed of ribonucleic acid and proteins and is not surrounded by any membrane.
- BIt is a single membrane-bound vesicular structure rich in various hydrolytic enzymes.
- CIt consists of many flat, disc-shaped sacs or cisternae stacked parallel to each other.
- DIt is an endomembrane structure which acts as a major site for the synthesis of lipids.
Correct answer
A. It is composed of ribonucleic acid and proteins and is not surrounded by any membrane.
Step-by-step solution
The granular structures first observed under the electron microscope as dense particles by George Palade (1953) are ribosomes. Ribosomes are composed of ribonucleic acid (RNA) and proteins and are not surrounded by any membrane. The other options describe lysosomes (vesicular structures with hydrolytic enzymes), Golgi apparatus (flat, disc-shaped sacs), and smooth endoplasmic reticulum (major site for lipid synthesis). Answer: It is composed of ribonucleic acid and proteins and is not surrounded by any membrane.