Living cells Subject

The chemical course of alcoholic fermentation, which has already been the subject of investigation for more than a century, has been explained chiefly by the work of C. Neuherg and G. Emhden. E. Buchner proved that zymase, the enzyme complex of yeast, can be separated from the living cells. 

Recent advances in mass spectrometry (MS) technology have provided researchers with an unparalleled ability to identify the types and patterns of secondary biochemical modifications found on proteins in living cells. Matrix-assisted laser desorption/ionization-MS (MALDI-MS) analyses have shown, for example, that HMGA proteins in vivo are simultaneously subject to complex patterns of phosphorylation, acetylation and methylation and that, within the same cell type, different isoforms of these proteins can exhibit quite different modification patterns [33]. Furthermore, these in vivo modifications have been demonstrated to markedly alter the binding affinity of HMGA proteins for both DNA and chromatin substrates in vitro [33]. Nevertheless, due to their number and complexity, it has been difficult to determine the actual biological function(s) played by these biochemical modifications in living cells. 

As defence mechanisms in plants commonly act in concert, it would be wrong to ascribe a primary role to these various wall alterations without additional investigation in virtually all cases evidence for the concomitant operation of chemical defences is also available. However, cell wall alterations are particularly well suited to long term defence, providing stable and durable barriers that are not dependant on the continuing metabolic activity of living cells to maintain them, and which are not subject to chemical instability or leaching. 

It is not the purpose of this essay to describe how enzymes work. Many excellent texts cover the subject. Enzymes are components of the system by which living cells, plants, and animals produce energy and nutrients. Possible food sources in the... 

In the second half of the nineteenth century, biologists first enlisted the cooperation of the chemist to delve into those mysteries of the living cell which the microscope is incapable of revealing. Inspired by an anatomist named His, F. Miescher (a young biochemist of Ba.sel) attempted chemical extraction from the cell of the substance having the characteristics of chromatin, the building unit of the chromosomes. He subjected pus cells to the action of dilute hydrochloric acid for several... 

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