a site of ribosome definition
Ribosomes are the protein builders or the protein synthesizers of the cell. They are like construction guys who connect one amino acid at a time and build long chains. Ribosomes are special because they are found in both prokaryotes and eukaryotes. Ribosomes of prokaryotes (e.g. bacteria) are smaller than most of the ribosomes of eukaryotes (e.g. plants and animals). However, the plastids and mitochondria in eukaryotes have smaller ribosomes similar to those in prokaryotes – a possible indication of the evolutionary origin of these organelles. A ribosome is a molecule consisting of two subunits that fit together and work as one to build proteins according to the genetic sequence held within the messenger RNA (mRNA). Using the mRNA as a template, the ribosome traverses each codon, pairing it with the appropriate amino acid. Translation (biology) In molecular biology and genetics, translation is the process in which ribosomes in a cell's cytoplasm create proteins, following transcription of DNA to RNA in the cell's nucleus. The entire process is a part of gene expression. The ribosome (/ˈraɪbəˌsoʊm, -boʊ-/) is a complex molecular machine, found within all living cells, that serves as the site of biological protein synthesis (translation). Ribosomes link amino acids together in the order specified by messenger RNA (mRNA) molecules. Ribosomes consist of two major components: the small ribosomal subunit, which reads the RNA, and the large subunit, which joins amino acids to form a polypeptide chain. Ribosomes are typically composed of two subunits: the large and small subunits. They join as one during translation; together, they catalyze the translation of mRNA into a polypeptide chain during protein synthesis, and since their active sites are made of RNA, ribosomes are also referred to as ribozymes.. When the cell needs to make a protein, mRNA is created in the nucleus. The mRNA is then sent out of the nucleus and to the ribosomes. When it is time to make the protein, the two subunits come together and combine with the mRNA. The subunits lock onto the mRNA and start the protein synthesis. Other ribosomes are found on the endoplasmic reticulum. Endoplasmic reticulum with attached ribosomes is called rough ER. It looks bumpy under a microscope. The attached ribosomes make proteins that will be used inside the cell and proteins made for export out of the cell. The sequence of DNA, which encodes the sequence of the amino acids in a protein, is copied into a messenger RNA chain. It may be copied many times into RNA chains. Ribosomes can bind to a messenger RNA chain and use its sequence for determining the correct sequence of amino acids. Ribosomes are formed in the cytoplasm of prokaryotic cells. In eukaryotic cells, they are formed most often in the nucleolus. Another difference between ribosomes of prokaryotes and eukaryotes is the structure of the ribosomes. Prokaryotes have 70S ribosomes, each consisting of a small (30S) and a large (50S) subunit. Eukaryotes have 80S ribosomes, each consisting of a small (40S) and large (60S) subunit.
A complex molecular machine, found within all living cells, that serves as the site of biological protein synthesis.