Question

Ribosomes are composed of
A. DNA + Protein
B. DNA
C. RNA + Protein
D. RNA + DNA

Answer 1

Hint:-Ribosomes are complex molecular machines which are specialized cell organelle, it is located in two areas of cytoplasm and scattered there.

Complete Answer:-
Ribosomes consist of two subunits, where one ribosomal unit is large and has dome-shaped whereas another ribosomal subunit is small and present above the larger subunit forming a cap-like structure. These two subunits remains united with each other because of the specific concentration of magnesium ions, and when there is a reduction in the critical level or concentration of magnesium ions the two ribosomal subunits separate from each other. Ribosomes are classified into two types 70S and 80S, where S shows the coefficient which indirectly measures the size and density of the ribosomes.
Ribosomes are composed of RNA and protein and therefore it is also known as ribonucleoprotein. Around 60% of the ribosomes comprise RNA and the rest 40% contain proteins. These are the sites in the cell where protein synthesis takes place.
Structure of Ribosome:

Some important functions of ribosomes include: They assemble amino acids for the formation of proteins which are essential to carry out cellular processes.
Free ribosomes synthesize non-secretory proteins whereas the endoplasmic reticulum synthesizes secretory proteins. These free ribosomes synthesize structural and enzymatic proteins. While attached ribosomes synthesize proteins for transport, that’s why these are also known as protein factories.
So, as we have discussed the correct answer is option C (RNA + Protein).

Note:- Prokaryotes ribosomes are of 70S while in eukaryotes it is 80S. In mitochondrial chloroplast, the ribosome is of 70S, the reason is that they are believed to have originated from the prokaryotes that were engulfed by the eukaryote and developed a symbiotic relationship.