Question

1. if you were trying to come up with an easy - to - remember analogy for the polymerase chain reaction, you would likely say pcr is similar to a ________.

dishwasher
colored pencils
photocopier
scissors

1. what determines the piece of dna that is amplified in pcr?

the specific restriction enzyme used
the specific primers used
the temperature of each cycle
the source of the dna

1. what is the role of temperature in pcr?

it is used to enhance building of the dna chains
it is required for the use of restriction enzymes
it is used to separate and anneal the nucleic acids

1. what best explains how pcr can be used to detect an infection?

specific temperatures are used to amplify dna from an infectious agent if it was present in the patient.
specific restriction enzymes are used to cut the dna from an infectious agent if it was present in the patient. that fragment can then be seen on a gel.
specific primers are used that would result in the amplification of dna from an infectious agent if it was present in the patient. that amplification can be seen with the presence of a specific size fragment when the pcr product is ran on a gel.

Explanation:

1. PCR (Polymerase Chain Reaction) is a technique used to amplify (make many copies of) a specific segment of DNA. A photocopier also makes multiple copies of a document, so it is a good analogy.
2. Primers are short, single - stranded DNA sequences that are complementary to the regions flanking the target DNA sequence. They determine where DNA synthesis will start, thus determining the piece of DNA that is amplified.
3. In PCR, different temperatures are used for different steps. High temperatures (e.g., 94 - 96°C) are used to denature (separate) the double - stranded DNA. Lower temperatures (e.g., 50 - 65°C) are used for annealing (binding of primers to the single - stranded DNA).
4. Specific primers are designed to be complementary to the DNA of a particular infectious agent. If the agent is present, these primers will bind to its DNA, and PCR will amplify that DNA. When the PCR product is run on a gel, a specific size fragment (corresponding to the amplified DNA of the infectious agent) can be seen.

Answer:

1. photocopier
2. The specific primers used
3. It is used to separate and anneal the nucleic acids
4. Specific primers are used that would result in the amplification of DNA from an infectious agent if it was present in the patient. That amplification can be seen with the presence of a specific size fragment when the PCR product is ran on a gel.