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a lab assistant needs to mix up the following reaction to prepare dna for an experiment:
25ul of a dna sample
25ul of enzyme
50ul of reaction buffer
400ul of water
the smallest size tube that will hold the entire reaction is [0.05, 0.5, or 5] ml:
which of the following pipetting devices most likely would not be used by the lab assistant to measure the needed volumes? ? [p20, p200, p1000]?
the enzyme comes as a concentrated solution of 20 units of activity per ul. therefore, the reaction mix will have total units of the enzyme at a working dilution of units/ul.

The smallest size tube that will hold the entire reaction is 0.5ml

Explanation:

25ul (DNA sample) + 25ul (enzyme) + 50ul (buffer) + 400ul (water) = 500ul total

since 1000ul=1ml, then 500ul = 0.5ml

The device that mostlikely would not be used P20

Explanation:

P20 is a pipette used to measure and sample volumes of 20ul maximum.

The reaction mix will have 400 units of the enzyme.

The working dilution will be 0.8 Units/ul.

Explanation:

The mix has 20ul of the enzyme which is 20Units/ul. Then we have 20ulx20Units/ul= 400 Units of enzyme in the mix.

Since the final volume is 500ul, the final concentration 400Units/500ul=0.8 Units/ul.

the correct answer is d