A Random Report

Ribosomes are organelles that were first observed in the 1950s by George Palade- a Romanian Scientist. Later they were “discovered” in 1974 by Albert Claude, Christian de Duve and George Emil Palade (they received the Nobel Prize for this- medicine). They were decidedly called ribosome’s deriving from the words ribonucleic acid and the Greek word Soma, meaning body. Later in 2009 three more scientist were honored with the Nobel Prize for their continuous study of the structure that is found in ribosomes.

Ribosome’s assemble proteins and consist of a larger and smaller unit. The larger unit is generally sixty percent of the ribosome and is ribosomal RNA, the last forty percent is made of proteins (at least in a eukaryotic cell), however whether the cell is prokaryotic or eukaryotic the percentages can change (prokaryotic- 30 and 50). During protein synthesis the smaller unit binds to mRNA and the larger binds to RNA and amino acids. Ribosome’s are generally spheres and are so small that they can only been seen under an electron microscope- there general size is around 20 nm (nm standing for nanometer- it is one billionth of a meter). In dry cells ribosome’s make up twenty five percent of the weight in the cell. Their structure and vulnerability can change depending on whether they are in bacteria, archaebacteria, or

Ribosome’s are reproduced in the nucleolus where they then come out and in a eukaryotic cell (a cell containing a nucleus and other organelles) they bind to the endoplasmic reticulum and by doing form rough ER. In a prokaryotic cell they hang in the cytosol or cytoplasm. This forms the two different types of ribosome’s- bound and free. Either of these ribosome’s are interchangeable and they type that are made are sent by a signal sequence, but bound ribosome’s form proteins that are made for the plasma membrane or are taken through exocytosis (the secretion of materials through the cellular membrane). Ribosome’s are classified as Ribozymes. Polyribosome’s or polysomes are groups of ribosome’s that are held together by messenger RNA.

To make proteins, ribosome’s work up and down Messenger RNA reading the genetic code called “codon” off of it (the Genetic Material is made from DNA because DNA makes RNA). This process is called translation. By translation the ribosomes know which proteins to form. The ribosome’s then take the amino acids which are attached to the mRNA and form peptyde bonds between the acids using tRNA which takes the amino acid to its spot in the chain where it is catalyzed by aminoacyl tRNA synthetase (the process of chemical reaction is sped up). The energy needed for this process is called guanosine triphosphate. The chain is then bound together by a different part of the ribosome, and when it has finished reading the part of the mRNA the two subunits break apart.