The science concerned with the chemistry of cells. Specifically, the macromolecules of subcellular structures can be treated chemically to form microscopically visible end products. For example, proteins, enzymes, lipids, carbohydrates, and nucleic acids can be directly visualized in cell nuclei, membranes, and organelles by cytochemical methods which generate images that can be viewed by either bright field or light, fluorescence, confocal, or electron microscopes. Cytochemistry
is the biochemistry of cells, especially that of the macromolecules responsible for cell structure and functioncell growth
The term cell growth
is used in two different ways in biology.When used in the context of reproduction of living cells the phrase "cell growth" is shorthand for the idea of "growth in cell populations
by means of cell reproduction." During cell reproduction one cell (the "parental" cell) divides to produce two daughter cells.In other contexts, "cell growth" refers to increases in cell structure.
Properties of Life
What defines something as living? Click here to find out.Molecule Transport
The cell must be able to obtain nutrients and other molecules to survive. Click here to learn about the process and machineries that are involved.Reproduction
Simply being able to sustain itself is not enough. Cells must be able to produce new generations to ensure the survival of their specie. Click here to find out the steps involved in cell replication.Cellular Metabolism
It takes energy to make things happen, even at the cellular level. Click here to learn how cell derives energy from its surrounding.Enzymes are biological catalysts, they are large protein molecules. They are many times larger than the molecules involved in the reaction they catalyse. Many enzymes require the presence of an additional molecule a non-protein cofactor. Some of these are metal ions such as Zn2+ and Cu2+. Some cofactors are small organic molecules called coenzymes. The B-group vitamins thiamine and riboflavin are precursors of coenzymes.Enzymes bind temporarily to one or more of the reactants of the reaction they catalyse. In doing so, they lower the amount of activation energy needed for the reaction to proceed and this speeds up the reaction. All metabolic reactions are catalysed by enzymesFigure 1 G = the change in energyThe following two specific examples of enzymes shows the amazing speed at which enzyme molecules can catalyse reactions.
1. Catalase catalyses the decomposition of hydrogen peroxide into water and oxygen.H2O2 H2O + O2
2. Carbonic anhydrase is found in red blood cells
CO2 + H2OCarbonic anhydrase
H2CO3 ( H+ + HCO3-)