Question

A cell organelle which lacks membrane, consists of 65% rRNA and 35% proteins and helps in protein synthesis is
(A) Nucleus
(B) Nucleoid
(C) Ribosome
(D) Nucleolus

Answer 1

Hint: Protein synthesis is the process in which cells make proteins. If protein synthesis does not happen then, there would be no DNA repairs leading to multiple mutations and could even lead to deadly diseases like cancer.

Complete answer:
An organelle is a subcellular structure that has one or more specific jobs to perform in the cell, much like an organ does in the body.
Option A: Nucleus is a double membrane bond past the cell which contains genetic material. Nucleoid is the term used for the naked single circular chromosome of prokaryotes which lie precisely in the cytoplasm of a cell.
Option B: Nucleoid is present in prokaryotic cells and it is an irregularly shaped region within the cell and consists of most of the genetic material. It is not surrounded by a nuclear membrane like nucleus and does not help in protein synthesis.
Option C: Ribosomes are the cell organelles which are not bounded by any membrane and are responsible for protein synthesis. They are made up of RNA and portions. therefore, this is the correct option.
Protein synthesis occurs two stages:
-Transcription is the transfer of genetic instructions in DNA to mRNA in the nucleus. It includes three steps: initiation, elongation and termination.
-Translation is the process by which the protein is synthesised from the information contained in mRNA
Option D: Nucleolus is a dense, rounded dark staining body inside the nucleus and is without a limiting membrane. It also consists of RNA and also forms ribosomal subunits.

Therefore, from the above explanation the correct option is (C) Ribosome.

Note: Ribosomal RNA \[\left( {rRNA} \right)\] associates with a set of proteins to form ribosomes. These complex structures which physically move along an mRNA molecule catalyzed the assembly of amino acids into portion chains. They also bind $tRNA$and various accessory molecules necessary for protein synthesis.