c
(c) : Ribosomes may occur in rosettes or helical groups called polyribosomes or polysomes (Gk. Poly -many, soma -body). The different ribosomes of a polyribosome are connected with a \(10 -20\ Å\) thick strand of messenger or \(mRNA\) and its maintenance requires energy. Polyribosomes are formed during periods of active protein synthesis when a number of copies of the same polypeptide are required.