Question

Which one of the following structures is an organelle within an organelle?
A. Ribosome
B. Peroxisome
C. Endoplasmic reticulum
D. Mesosome

Answer 1

Cells are the basic unit of multicellular organisms. They have different types of organelles like endoplasmic reticulum, chloroplasts, mitochondria, lysosomes, ribosomes, peroxisomes, etc. All these organisms have their respective functions to perform in a cell.

Complete answer:
- Cells are usually membrane-bound. Plant cells also have cellulose cell walls.
- Nucleus contains the genetic material and is membrane-bound in eukaryotic cells.
- In eukaryotic cells, the endoplasmic reticulum is usually in continuation with the nuclear membrane and is of two types, rough endoplasmic reticulum, and smooth endoplasmic reticulum.
- Smooth endoplasmic reticulum is responsible for the biosynthesis of lipids and fatty acid and the rough endoplasmic reticulum has ribosomes on its surface and is responsible for the synthesis of protein.
- Golgi apparatus consists of the cisternae, tubules, vesicles, golgi vacuoles. It processes, packages, and transports the material to be secreted.
- Lysosomes are sac-like organelles in the cytoplasm that contain hydrolytic enzymes like lipases, proteases, carbohydrases, etc.
- Mitochondria is a double membrane-bound cellular organelle that is most often known as the powerhouse of the cell. It is responsible for the synthesis of ATP with the help of elementary particles present in its inner membrane. Mitochondria has its own ribosomes.
- Chloroplasts have a three membrane system having the outer inner and thylakoid membrane. They also possess their own ribosomes.
- It can be observed that ribosomes are present in the cytoplasm, smooth endoplasmic reticulum, inside mitochondria and chloroplast. Therefore, we can refer to ribosomes as organelle within an organelle.

The answer is (A) Ribosome

Note:
- George Palade in 1953 discovered the Ribosomes.
- Ribosomes are types: 70S and 80S, where S represents the sedimentation coefficient which indirectly measures the density and size of the ribosomes.