The surfaces of the two ribosomal subunits that face one another contain the binding sites for the mRNA and incoming tRNAs and are thus key for the function of the ribosomes. The fact that these surfaces consist largely of RNA supports what proposal?
A)primordial ribosomes were composed solely of proteins
B)primordial ribosomes were composed exclusively of RNA
C)primordial ribosomes were composed exclusively of DNA
D)prokaryotes gave rise to eukaryotes
E)endosymbiosis gave rise to eukaryotes

Question

Quizplus · Accepted Answer

The fact that the surfaces of the ribosomal subunits consist largely of RNA supports the proposal that primordial ribosomes were composed exclusively of RNA. This is known as the RNA world hypothesis, which suggests that primitive life forms relied on RNA for both genetic information and catalytic activity before the evolution of DNA and proteins.

The Surfaces of the Two Ribosomal Subunits That Face One