Environmental Microbiology of Aquatic and Waste Systems

3.3 Microarrays 39

Action/ExplanationComponents Cycle

Heat together to

95°C:

Ds DNA, Primer and

heat-stable Taq

polymerase

Double-stranded

DNA separates at

95°C:

Strands separate

Cool to 54°C:

Primer has bases

complementary to

some on ss DNA;

hence anneals with

ss DNA

Heat to 75°C,

optimum temp for

Taq polymerase:

Taq polymerase

becomes active and

ss DNA extends and

ds DNA forms

ss DNA becomes ds

DNA

ie quantity of DNA

now double

F I R S T C Y C L E

Ds

DNA

Primer Taq polymrase

SS

DNA

SS

DNA

All three continue

to be heated

together to 95°C in

second cycle:

Ds DNA, Primer and

heat-stable Taq

polymerase

New double-

stranded DNA

separates at 95°C:

Strands separate

Cool to 54°C:

Primer has bases

complementary to

some on ss DNA;

hence anneals with

ss DNA

Heat to 75°C,

optimum temp for

Taq polymerase:

Taq polymerase

becomes active and

each of the two ss

DNA extends and

four ds DNA form

ss DNA becomes

ds DNA

ie quantity of DNA

now double,

become 4 times in

second cycle

S E C O N D C Y C L E

Fig. 3.4 Diagrammatic representation of PCR