Median for ungrouped data:

Median = [(n+1)/2]th observation, if n is odd.

Median = mean of (n/2)th observation and [(n/2)+1]th observation, if n is even.

#Id: 2592

#Unit 13. Methods in Biology

The logic for hotstart PCR is as follows, most DNA samples used as template will have some single-stranded DNA. 

#Id: 2593

#Unit 13. Methods in Biology

In case of hotstart PCR, After the reaction mixture is prepared, primers can pair to the single-stranded regions in a nonspecific manner. 

A more attractive alternative is to cover the reaction mixture with a plug of inert wax and place the critical reagent on top of this plug. 

#Id: 2594

#Unit 13. Methods in Biology

A more attractive alternative is to cover the reaction mixture with a plug of inert wax and place the critical reagent on top of this plug. 

#Id: 2595

#Unit 13. Methods in Biology

Oligonucleotide-directed mutagenesis

The basic PCR mutagenesis system involves the use of two primary PCR reactions to produce two overlapping DNA fragments, both bearing the same mutation in the overlap region; this technique is thus termed overlap extension PCR .

#Id: 2596

#Unit 13. Methods in Biology

Oligonucleotide-directed mutagenesis.

This technique requires a knowledge of nucleotide sequence, since an oligonucleotide may then be synthesized with the base mutation. 

Annealing of the oligonucleotide to complementary (except for the mutation) single-stranded DNA provides a primer for DNA polymerase to produce a new strand and thus incorporates the primer with the mutation.

#Id: 2597

#Unit 13. Methods in Biology

Molecular beacons gives an idea for annealing.