Question

Peptide synthesis inside a cell takes place in which of the following organelle?
A. Ribosomes
B. Chloroplast
C. Mitochondria
D. Chromoplast

Answer 1

Peptide synthesis is the production of peptides, in which multiple amino acids are linked via peptide bonds. When a condensation reaction takes place between the carboxyl group of one amino acid and the amino group of another, peptides are formed.

Complete answer:
-Ribosomes are the site of protein synthesis. They are composed of RNA and proteins which are surrounded by any membrane. The eukaryotic ribosomes are 80S and are divided into 60S and 40S. The prokaryotic ribosomes are 70S and are divided into 50S and 30S.
-Chloroplasts are the site for photosynthesis. They contain chlorophyll pigments which are responsible for trapping light energy essential for photosynthesis. They are concentrated in the parenchyma cells of the leaf mesophyll. They give green colouration to the plant. Hence, ‘option B’ is incorrect.
-Mitochondria are the sites of aerobic respiration. During respiration, cellular energy in the form of ATP is produced inside mitochondria, hence they are called ‘powerhouses’ of the cell. They are double-walled structures with the inner membrane forming a number of infoldings called the cristae. Hence ‘option C’ is incorrect.
-Chromoplasts are fat-soluble carotenoid pigments like carotene and xanthophylls. They are responsible for different colours like yellow, orange and red colour imparted to fruits, flowers, old leaves, etc. Hence, ‘option D’ is incorrect.

Hence, the correct answer is option (A).

Note: Ribosomes consist of a large and small subunit, which come together around an mRNA molecule when translation takes place. Each subunit is a combination of proteins and rRNA. The rRNA helps to secure both the mRNA and tRNA in the ribosome and acts as a catalyst in the process of protein synthesis.