Skip to main content

Ribosome Structure: Large and Small Subunits

This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.

State

A ribosome is built from a large and a small subunit, each made of ribosomal RNA and protein, joining together only during translation.

Show

The small subunit binds mRNA first, and the large subunit joins afterward to form the complete, functional ribosome.

Watch for

A ribosome's two subunits exist separately in the cell most of the time — they assemble specifically to translate an mRNA.