Term
| polymerase chain reaction (PCR) |
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Definition
| An enzymatic technique for the rapid production of millions of copies of a particular stretch of DNA where only a small amount of the parent molecule is available. |
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Term
| What does the PCR reaction mixture contain? |
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Definition
- double stranded DNA, to act as the template
- two short, artificially synthesized primers that are complementary to the ends of the sequence to be amplified
- the four dNTPs (dATP, dTTP, dCTP and dGTP)
- a DNA polymerase that can tolerate high temperatures
- salts and a buffer to maintain a near-neutral pH.
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Term
| What is the first step of PCR? |
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Definition
- The first step involves heating the reaction to near boiling point, to separate (denature) the two strands of the DNA template.
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Term
| What is the second step of PCR? |
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Definition
- The reaction is cooled to allow the primers to bind (or anneal) to the template strands.
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Term
| what is the third step of PCR? |
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Definition
| the reaction is warmed to an optimum temperature for the DNA polymerase to catalyze the production of the complementary new strands. |
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Term
| What was a problem with PCR? |
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Definition
| temperature requirements. To denature the DNA, it must be heated to more than 90°C—a temperature that destroys most DNA polymerases. |
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Term
| How was the problem with PCR solved? |
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Definition
The problem was solved by nature: in the hot springs at Yellowstone National Park, as well as in other high-temperature locations, there lives a bacterium called, appropriately, Thermus aquaticus, which survives temperatures up to 95°C
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