All exams GA
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Ribosomes are molecular machines that synthesize proteins in all cells. They are made of RNA and protein, and are found in the cytoplasm of cells.
- How ribosomes work
- Ribosomes read the messenger RNA (mRNA) sequence.
- They translate the genetic code into a string of amino acids.
- The amino acids are added to a growing protein chain.
- When the ribosome reaches a stop codon, it releases the finished protein.
- Types of ribosomes
- 70S ribosomes: Prokaryotic cells that include bacteria and archaea.
- 80S ribosomes: Eukaryotic cells that include plants, animals, and fungi.
- Number of ribosomes in a cell
- The number of ribosomes in a cell depends on the level of its activity in protein synthesis.
- Growing cells contain numerous ribosomes.
- One eukaryotic cell may have as many as 10 million ribosomes.
- Discovery of ribosomes
- George E. Palade discovered the first ribosomes in 1955.
- He won the Nobel Prize in 1974.
