The Three Domain

The Three Domain

The Three Domain System, proposed by Woes and others, is an evolutionary model of classification based on: I) differences in the sequences of nucleotides in the cell’s ribosomal RNA (RNA), it) the cell’s membrane lipid structure iii) its sensitivity to antibiotics. Comparing RNA structure is especially useful. Because RNA molecules throughout nature carry out the same function, their structure changes very little over time. Therefore similarities and dissimilarities in RNA nucleotide sequence are a good indication of how related or unrelated different cells and organisms are.

The Bacteria and the Eukaryote have membranes composed of unbranded fatty acid chains attached to glycerol by ester linkages. The Archie have membranes composed of branched hydrocarbon chains attached to glycerol by ether linkages. Eve Human evolution… What do you think? Evolution: Theory & Sciences all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth. The green and budding twigs may represent existing species; and those produced during each former year may represent the long succession of extinct species …

The limbs divided into great branches, and these into lesser and lesser branches, were themselves once, when the tree was small, budding twigs; and this connection of the former and present buds by ramifying branches may well represent the classification of all extinct and living species in groups subordinate to groups … From the first growth of the tree, many a limb and branch has decayed and dropped off, and these lost branches of various sizes may represent those whole orders, families, and genera which have now no living representatives, and which are known o us only from having been found in a fossil state …

As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtook on all a feebler branch, so by generation I believe it has been with the Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its Prokaryotic cells are generally much smaller and more simple than eukaryotic. The smaller a cell, the greater is its surface-to-volume ratio. A large surface-to-volume ratio, as seen in smaller prokaryotic cells, meaner that nutrients can easily and vapidly reach any part of the cells interior.

In the larger eukaryotic cell, the limited surface area when compared to its volume meaner nutrients cannot rapidly diffuse to all interior parts of the cell. That is why eukaryotic cells require a variety of specialized internal organelles to carry out metabolism, provide energy, and transport chemicals throughout the cell. Both, have to carry out the same life biochemical processes. Cells with a high metabolic rate are usually small. Why? Higher magnification Structure of virus: nucleic acid with a protein envelope Virus: genetic parasite! Is it a cell?