The protein-building structures contained in all cells are ribosomes. Thousands of these structures are present in cells, with more present in cells that make lots of proteins. Ribosomes take the genetic message of DNA and translate it into proteins.Continue Reading
Sixty percent of a ribosome is ribosomal RNA, or rRNA. The other 40 percent is made of protein. Ribosomes are made in the nucleus, namely, the nucleolus, of a cell. A large and small subunit make up a ribosome. When not making proteins, the subunits exist separately in the cytoplasm. The two subunits join when proteins need to be made.
Ribosomes can exist independently in the cytoplasm of cells or be stuck to the membrane of the nucleus or the endoplasmic reticulum to form the rough endoplasmic reticulum. Unattached ribosomes generally make proteins for the cell's use, whereas those attached to the endoplasmic reticulum are usually bound for transport outside the cell.Learn more about Cells
The nucleolus is chiefly responsible for creating ribosomes, which in turn function as factories for protein synthesis. The nucleolus contains three main organizing regions where transcription and processing of rRNA occurs. It also purportedly aids in other processes, like the packaging of signal recognition particles and the alteration of transfer RNA. The nucleolus is located in the nucleus, and thus only exists in eukaryotic cells.Full Answer >
The ribosomes in the cytoplasm are the sites of protein translation in the cell. Translation refers to taking a copy of messenger RNA, or mRNA, and making a protein from the code.Full Answer >
All cells, which include eukaryotic and prokaryotic cells, have a plasma membrane, DNA, ribosomes and cytoplasm. The plasma membrane is a protective barrier that separates the cell from the rest of its environment. The plasma membrane does allow material to be transported through it.Full Answer >
In the cells of eukaryotic organisms, the subunits that will become ribosomes are produced within the subnuclear structure called the nucleolus, and the subunits then combine in the cell's cytoplasm to become functioning ribosomes. Because the ribosomes are the protein manufacturers of a cell, the size of the nucleolus can take up as much as 25 percent of the volume of the nucleus in cells that require large amounts of protein. Most eukaryotic cells contain only one nucleolus, but certain species can contain several.Full Answer >