Question

Which part of the cell acts as a site for synthesis of proteins?
A. Ribosome
B. Golgi apparatus
C. Mitochondria
D. Plastid

Answer 1

Hint:- Proteins are the polypeptides of amino acids that are linked through peptide bonds. There are different forms of proteins- primary, secondary, tertiary and quaternary. Among these tertiary structures of the protein is considered the functional state.

Complete answer: Ribosomes- These were discovered by Claude who called them Microsome. Palade in 1995 coined the term ribosome. These are the smallest cell organelles that are devoid of membrane. There are two forms of ribosomes – bound form and free ribosomes. Bound forms are attached to the Endoplasmic reticulum and are involved in protein synthesis. Free ribosomes are present in hyaloplasm and help in protein synthesis for growth of protoplasm.
Golgi apparatus- Golgi bodies were first discovered in nerve cells of the cat and owl by Camillo Golgi. It is found in all cells except RBC of mammals and muscle cells. In plant cells, the Golgi complex consists of many unconnected units known as dictyosomes. Its number varies from cell to cell. It is associated with glycosidation of lipids and proteins to produce and glycoproteins.
Mitochondria- It is an organelle that provides an energy transducing system by which the chemical energy obtained in food stuff is converted by oxidative phosphorylation into high-energy phosphate bonds (ATP).
Plastid is a double walled, DNA containing largest organelles in plant cells that was discovered by Haeckel in 1865. These are of various types:
Chromoplasts- These are the plastids containing different types of pigments like carotenoids, xanthophyll, chlorophylls, etc.
Leucoplasts- These plastids are devoid of pigments and internal lamellar structures. It stores food in different forms like starch, fat, oil and protein.
Chloroplasts- These are green plastids discovered by Sachs in 1862. The shape and size of the chloroplasts vary in different cells within a species but these organelles are relatively constant within the cells of the same tissue. These are the sites for photosynthesis.
So the correct answer is 1. Ribosome.

Note:- Each ribosome in prokaryotes as well as eukaryotes is composed of two subunits i.e. larger and smaller subunits. The smaller subunit shows an oblate ellipsoid and cap-like structure while the larger subunit appears dome-shaped.