Which physiological process is facilitated by the ribosome organelle?

Ribosomes are composed of ......... and in a polysome complex,......... is present.

Which cell organelle is described by the following statements?
$(A)$ Granular structure.
$(B)$ First observed under an electron microscope as dense particles by $George\, Palade$.
$(C)$ Composed of $RNA$ and proteins.
$(D)$ Not surrounded by any membrane.

$A$ polyribosome is formed by the arrangement of which of the following?

The endoplasmic reticulum often bears

$70S$ ribosomes are composed of which subunits?