• 12 parts
  • Checked September 2026

Ribosome Diagram Labeled

One ribosome at work, then where ribosomes sit in a cell.

Ribosome Diagram Labeled

Name Date

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1 2 3 4 5 6 7 8 9 10 11 12
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Write the name of each numbered part.Answer key

  1. Large subunit
  2. Small subunit
  3. Ribosomal RNA
  4. Ribosomal proteins
  5. mRNA
  6. tRNA
  7. Polypeptide chain
  8. Nucleolus
  9. Free ribosomes
  10. Bound ribosomes
  11. Rough ER
  12. Polysome

Drawn for this site by script, 2026-09-27. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: translation, step by step

All 12 parts on the diagram

Show the list

Start here: 5 main parts 5

  1. Large subunit The larger of the ribosome's two parts. It joins the amino acids into a chain.
  2. Small subunit The smaller of the two parts. It holds the mRNA and reads its code.
  3. mRNA Messenger RNA, the copy of a gene that the ribosome reads.
  4. tRNA Transfer RNA, which brings the amino acid that matches each mRNA codon.
  5. Polypeptide chain The chain of amino acids the ribosome is building. It will fold into a protein.

What it is made of: 2 2

  1. Ribosomal RNA Ribosomal RNA, the RNA each subunit is built around. It does the actual chemistry of joining amino acids.
  2. Ribosomal proteins The many proteins built into each subunit alongside the rRNA.

In the cell: 5 5

  1. Nucleolus The region inside the nucleus where the rRNA is made. The subunits are put together here.
  2. Free ribosomes Ribosomes floating in the cytoplasm. The proteins they make stay in the cell.
  3. Bound ribosomes Ribosomes on the rough endoplasmic reticulum.
  4. Rough ER Folded membranes, rough-looking because of the ribosomes on them. In full, the rough endoplasmic reticulum.
  5. Polysome Several ribosomes moving along one mRNA at once. Each makes its own copy of the protein.

How this list was compiled: Read 2026-09-27. Wikipedia, Ribosome, https://en.wikipedia.org/wiki/Ribosome : the ribosome decodes codons in an mRNA and, with tRNA, joins amino acids into a polypeptide chain; a ribosome has a small and a large subunit, each of one or more ribosomal RNA molecules and many ribosomal proteins; ribosomes are free, floating in the cytoplasm (their proteins released into the cytosol), or membrane-bound, attached to the rough endoplasmic reticulum; a polysome of two or more ribosomes can move along one mRNA at a time; in eukaryotes they are assembled partly in the nucleolus. Licence: own work

The drawing: Drawn for this site by script, 2026-09-27. Own work, nothing traced. Licence: own work

How it works

A ribosome diagram labeled in two views: one ribosome building a protein, then where ribosomes sit in a cell. Start with the 5 main parts.

Read the full guide

One ribosome

A ribosome has two parts, a large and a small subunit, each built from ribosomal RNA and proteins. The mRNA runs between them; tRNAs bring amino acids, and the polypeptide chain grows out of the top.

In the cell

Ribosomes are made in the nucleolus. Free ribosomes float in the cytoplasm; bound ribosomes sit on the rough ER. Several can read one mRNA at once, as a polysome.

  • Several ribosomes can read the same mRNA at once, each making its own copy of the protein: that string is a polysome.

Questions and answers

What are the two parts of a ribosome?

The large subunit and the small subunit. Each is made of ribosomal RNA and many proteins, and they clamp together round an mRNA to build a protein.

What is the difference between free and bound ribosomes?

Free ribosomes float in the cytoplasm and make proteins used inside the cell. Bound ribosomes sit on the rough endoplasmic reticulum.

Where are ribosomes made?

In eukaryotic cells, their RNA is made and the subunits are put together partly in the nucleolus, inside the nucleus.

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