BioScience Dictionary

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Found PH 1861 times.

Displaying results 1 to 10.

1. 12-O-tetradecanoylphorbol-13-acetate (TPA)
A plant phorbol ester which promotes tumor formation by activating membrane protein kinase C.

2. 5-hydroxymethylcytosine
A nucleotide base derived from cytosine which is used by the bacteriophage T4 in place of cytosine in its DNA . The substitution protects the bacteriophage from its own nuclease enzyme s (enzymes which cut apart DNA).

3. 6-mercaptopurine
A toxic drug used to treat acute forms of leukemia (lymphocitic and granulocytic) by inhibiting DNA synthesis.

4. 6-thioguanine
Purine base analog which hypozanthine-guanine phosphoribosyl transferase (HGPRT) transforms into a toxin .

5. Abiotrophy
Premature loss of a cell's or tissue's ability to function.

6. Absolute gravity
In chemistry, the value that denotes the density (specific gravity) at standard conditions (for gases, these conditions are standard atmospheric pressure at 0 C).

7. Absorbance (optical density)
This is a measure of the amount of light absorbed by a suspension of bacterial cells or a solution of an organic molecule; it is measured by a colorimeter or spectrophotometer . Absorbance values are used to plot the growth of bacteria in suspension culture s and to gauge the purity and concentration of molecules (such as proteins) in solution. Absorbance is defined as a logarithmic function of the percent transmission of a wavelength of light through a liquid.

8. Absorption
The process of absorbing; specifically: * In physiology, it refers to the movement of liquids and solute s into cells by way of diffusion or osmosis. * In chemistry, it refers to the drawing of a gas or liquid into the pores of a permeable solid. * In immunology, it refers to a process in which an antigen or antibody is used to pull an analogous antigen or antibody out of a solution. Compare adsorption .

9. Absorption spectroscopy
This is the use of a spectrophotometer to measure the ability of particles (solutes) in a solution to absorb light through a range of specific wavelengths. Every compound absorbs light differently, so absorption spectra can be used to identify compounds, measure concentrations, and determine reaction rates.

10. Absorption spectrum
A graph of the amount of light a substance absorbs, plotted as a function of energy, frequency or wavelength.

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