ribosome

American  

[rahy-buh-sohm] / ˈraɪ bəˌsoʊm /

noun

Cell Biology.

1. a tiny, somewhat mitten-shaped organelle occurring in great numbers in the cell cytoplasm either freely, in small clusters, or attached to the outer surfaces of endoplasmic reticula, and functioning as the site of protein manufacture.

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ribosome British  

/ ˈraɪbəˌsəʊm /

noun

1. any of numerous minute particles in the cytoplasm of cells, either free or attached to the endoplasmic reticulum, that contain RNA and protein and are the site of protein synthesis

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ribosome Scientific  

/ rī′bə-sōm′ /

1. A sphere-shaped structure within the cytoplasm of a cell that is composed of RNA and protein and is the site of protein synthesis. Ribosomes are free in the cytoplasm and often attached to the membrane of the endoplasmic reticulum. Ribosomes exist in both eukaryotic and prokaryotic cells. Plastids and mitochondria in eukaryotic cells have smaller ribosomes similar to those of prokaryotes.

2. See more at cell

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ribosome Cultural  

1. A small, ball-like structure in the cell, made of proteins and RNA molecules, that serves as a platform on which the cell's proteins are made.

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Other Word Forms

• ribosomal
  adjective

Etymology

Origin of ribosome

First recorded in 1955–60; ribo(se) + -some ³

Explanation

A ribosome is a tiny part of a cell with the specific job of making protein. All living cells contain ribosomes. Ribosomes are the organelles responsible for RNA translation, the process of building protein out of amino acids using RNA. The ribosome translates code it finds in strands of messenger RNA, using it to form the new proteins needed by the cell. Microbiologist Richard B. Roberts coined ribosome from the complex scientific phrase "ribonucleoprotein particles of the microsome fraction."

Example Sentences

The Stanford team found that aging-related disruptions in protein synthesis, particularly involving ribosomes, can explain why this disconnect occurs.

From Science Daily • May 29, 2026

Follow-up studies using additional methods, including optical microscopy, revealed that the interior of these tubes contains many ribosomes, the structures responsible for protein production.

From Science Daily • Dec. 3, 2025

Now, a team of international scientists, including University of Michigan researchers, have used advanced microscopy to image how ribosomes recruit to mRNA while it's being transcribed by an enzyme called RNA polymerase, or RNAP.

From Science Daily • Nov. 28, 2024

The nucleolus isolates the rDNA which encodes the RNA portions of the ribosomes, the protein-building machinery.

From Science Daily • Nov. 25, 2024

The fussy biochemical setup had taken weeks to perfect—except each time the ribosomes were caught, they crumbled and fell apart.

From "The Gene" by Siddhartha Mukherjee