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The "A260 unit" is used as a quantity measure for nucleic acids. One A260 unit is the amount of nucleic acid contained in 1 mL and producing an OD of 1. The same conversion factors apply, and therefore, in such contexts: 1 A260 unit dsDNA = 50 μg 1 A260 unit ssDNA = 33 μg 1 A260 unit ssRNA = 40 μg
A number of different units (some only of historical interest) are shown and expressed in terms of the corresponding SI unit. Conversions between units in the metric system are defined by their prefixes (for example, 1 kilogram = 1000 grams, 1 milligram = 0.001 grams) and are thus not listed in this article.
In the metric system, a microgram or microgramme is a unit of mass equal to one millionth (1 × 10 −6) of a gram. The unit symbol is μg according to the International System of Units (SI); the recommended symbol in the United States and United Kingdom when communicating medical information is mcg .
However, the names of all SI mass units are based on gram, rather than on kilogram; thus 10 3 kg is a megagram (10 6 g), not a *kilokilogram. The tonne (t) is an SI-compatible unit of mass equal to a megagram (Mg), or 10 3 kg. The unit is in common use for masses above about 10 3 kg and is often used with SI prefixes.
Although there are examples to the contrary, it should be stressed that the commonly used "units" of % w/v are grams per millilitre (g/mL). 1% m/v solutions are sometimes thought of as being gram/100 mL but this detracts from the fact that % m/v is g/mL; 1 g of water has a volume of approximately 1 mL (at standard temperature and pressure) and ...
However, a transformation efficiencies as high as 0.5-5 x 10 10 colony forming units (CFU) per microgram of DNA for E. coli. For samples that are hard to handle, like cDNA libraries , gDNA , and plasmids larger than 30 kb, it is suggested to use electrocompetent cells that have transformation efficiencies of over 1 x 10 10 CFU/μg.
The two alternatives are to abbreviate as "mcg" [14] [3] or to write out "microgram" in full (see also List of abbreviations used in medical prescriptions). The alternative abbreviation may be ambiguous in rare circumstances in that mcg could also be read as a micrigram , i.e. 10 −14 g; however the prefix micri is not standard, nor widely ...
Sums of units (e.g., btu + ft lbf) can be converted. Conversions can be made to sums of units, termed unit lists (e.g., from degrees to degrees, minutes, and seconds). Units that measure reciprocal dimensions can be converted (e.g., S to megohm). Parentheses for grouping are supported.