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Human Body Study

Ribosomes

The cell’s protein factories — tiny machines that read genetic instructions and build proteins.

Schematic of a generalized animal cell A labelled cross-section of a generalized animal cell. Each label links to the article for that part: the cell membrane, cytoplasm, nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes and cytoskeleton. rough ER smooth ER Cell membrane Mitochondria Nucleus Endoplasmicreticulum Lysosomes Cytoskeleton Cytoplasm Ribosomes Golgi apparatus A generalized animal cell — schematic, not to scale. Not every cell contains every structure.

Structure

Section titled “Structure”

Made of RNA and protein, in two interlocking subunits. Some float free in the cytoplasm; others are attached to the endoplasmic reticulum.

What it does

Section titled “What it does”
  • Translation — reads a messenger-RNA copy of a gene and links amino acids in the specified order to build a protein.
  • Division of labor — free ribosomes make proteins for use inside the cell; attached ribosomes make proteins destined for membranes or for export.

Key idea

Section titled “Key idea”

Ribosomes are where the genetic code is finally cashed in — the step that turns information into a working molecule.