Question

What are ribosomes?
A) Ribosomes are spherical organelles present in the cell freely distributed in the cytoplasm
B) Ribosomes may be attached to the endoplasmic reticulum
C) Ribosomes are involved in the synthesis of proteins
D) All the above

Answer 1

Hint: Ribosomes are minute particles that are made of RNA and associated proteins. They are found more inside the cytoplasm of living cells.

Complete answer:
The ribosome is a multifaceted molecule composed of ribosomal RNA molecules and proteins. It creates a factory for protein synthesis in cells. Ribosomes are tiny spherical organelles that produce proteins when amino acids are joined together. Inside the cytosol, several ribosomes are found free and few others are fastened to the rough endoplasmic reticulum. This forms the rough Endoplasmic Reticulum. A mammalian cell consists of around 10 million ribosomes. Ribosome translates encoded messages from messenger RNA (mRNA) to proteins with the aid of tRNA. A polysome structure is formed when several ribosomes are attached to the same mRNA strand. During the transfer of RNA (tRNA) molecule amino acid is provided. Every newly translated amino acid is then combined with the growing protein chain. This will continue until the ribosome performs the process of protein synthesis. The mRNA provides the genetic information encoded in the original DNA. They act as a messenger to produce the appropriate proteins.

Hence the correct answer is option ‘D’.

Note: Ribosomes were discovered in 1955 by George E. Palade. He named them as tiny particles in the cytoplasm. This made it to be associated with the endoplasmic reticulum membrane. Every ribosome has a big and small component that collectively forms a single unit. That unit is composed of different ribosomal RNA molecules and dozens of proteins.