File:Average prokaryote cell- en.svg. Ribosome. Figure 1 : The ribosome assembles polymericproteinmolecules whose sequence is controlled by the sequence of messenger RNA molecules. This is required by all living cells and associated viruses. The sequence of DNA encoding for a protein may be copied many times into messenger RNA (mRNA) chains of a similar sequence. Ribosomes can bind to an mRNA chain and use it as a template for determining the correct sequence of amino acids in a particular protein.
Amino acids are selected, collected and carried to the ribosome by transfer RNA (tRNA molecules), which enter one part of the ribosome and bind to the messenger RNA chain. The attached amino acids are then linked together by another part of the ribosome. Once the protein is produced, it can then 'fold' to produce a specific functional three-dimensional structure. A ribosome is made from complexes of RNAs and proteins and is therefore a ribonucleoprotein. Discovery[edit] Structure[edit] High-resolution structure[edit] Function[edit] Cell (biology) The cell (from Latin cella, meaning "small room"[1]) is the basic structural, functional and biological unit of all known living organisms.
Cells are the smallest unit of life that can replicate independently, and are often called the "building blocks of life". The study of cells is called cell biology. The cell was discovered by Robert Hooke in 1665. The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that all cells come from preexisting cells, that vital functions of an organism occur within cells, and that all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.[5] Cells emerged on Earth at least 3.5 billion years ago.[6][7][8] Anatomy There are two types of cells, eukaryotes, which contain a nucleus, and prokaryotes, which do not.
Prokaryotic cells Eukaryotic cells Subcellular components Membrane. Prokaryotes, Eukaryotes, & Viruses Tutorial. Prokaryotes, Eukaryotes, & Viruses Tutorial. Prokaryotes, Eukaryotes, & Viruses Tutorial. Recent studies show that having low virus levels allow longer life (Science 272, 1124 (1996)) Molecular studies of HIV have led to the development of drugs that interfere with viral biology. Taking a combination of three drugs, indinavir, zidovudine, and lamivudine caused 85% of patients to have no detectable virus in their blood. Data being collected will show if these and other drugs will make AIDS treatable. Prokaryotes, Eukaryotes, & Viruses Tutorial. Prokaryotes, Eukaryotes, & Viruses Tutorial.