Particles isolated from a bacterium have the following properties: I. They measure approximately 15 nm by 20 nm. II. The

Practice question

Question

Particles isolated from a bacterium have the following properties:
I. They measure approximately 15 nm by 20 nm.
II. They are associated with the plasma membrane.
III. Each particle contains 50S and 30S subunits.
IV. Several may attach to the same mRNA.
Which conclusion correctly integrates all four observations?

Options

Choose one · Correct answer highlighted

They are 80S ribosomes that form grana during photosynthesis. They are 70S prokaryotic ribosomes that may form a polysome while translating one mRNA. Correct They are mesosomes that package proteins into lysosomal vesicles. They are inclusion bodies that store mRNA within a membrane.

Explanation

Prokaryotic ribosomes are approximately 15 nm by 20 nm, are associated with the plasma membrane and contain 50S and 30S subunits, forming a 70S ribosome. Several ribosomes on one mRNA constitute a polysome.

Share this question