Ribosomes

By: Tiffany Mathes, Symantha Inman

What are ribosomes?

Non-membrane organelles in the nucleus where proteins are assembled.

What do they do?

ribosomes, basically, is the machinery that helps build proteins. Ribosomes are found outside the cell's nucleus and work with mRNA and tRNA to form proteins from amino acids. mRNA fits within the ribosomes, and each codon (a set of three ribonucleic acids) code for a specific amino acid. The tRNA attaches the amino acid to the last on the chain and then leaves. Then, the ribosomes moves one codon down the chain, to code for the next amino acid. This process ends up building a strand of amino acids (protein!). After this stage, proteins fold into tertiary or quaternary structures and become functional in your body. (hemoglobin is a tertiary protein). I wish I could draw you a picture! In a nutshell, ribosomes are involved and VERY crucial to protein synthesis.

Where do you find them?

There are two places that ribosomes usually exist in the cell: suspended in the cytosol and bound to the endoplasmic reticulum. These ribosomes are called free ribosomes and bound ribosomes respectively. In both cases, the ribosomes usually form aggregates called polysomes.

Free ribosomes usually make proteins that will function in the cytosol, while bound ribosomes usually make proteins that are exported or included in the cell's membranes. Interestingly enough, free ribosomes and bound ribosomes are interchangeable and the cell can change their numbers according to metabolic needs.

Are they a prokaryotic and eukaryotic cells?

They are in both prokaryotic and eukaryotics.
Bacterial ribosome translating RNA into protein