Question

1. What would happen to the white blood cells if they were extracted in anything other than isotonic conditions? Describe what would happen to the cheek cells in hypertonic and hypotonic solutions respectively.

2. The polymerase chain reaction can only be used to amplify genes that have already been cloned and sequenced. Why is this true?

3. If you started a PCR protocol with 10 double-stranded molecules of DNA, how many double-stranded molecules of the product would you have after 5 cycles of PCR?

4. What is the purpose of including a PCR reaction with no added DNA? Isn't this just a waste of expensive enzymes when we know that without template, you will not get any PCR products?

5. What is the purpose of using DNA polymerase from Thermus aquaticus for the polymerase chain reaction rather than a DNA polymerase from a better-characterized bacterium such as E. coli?

Answer 1

1.

If white blood cells are extracted in hypertonic conditions, then water will exit the white blood cells and enter into the surrounding solution. This will result in the shrinkage of cells.

If white blood cells are extracted in hypotonic condition, then water will enter into the cells resulting in their swelling. If it continues to happen, then the cells may burst.

Same thing will happen with cheek cells.

2.

The given statement is correct because to perform polymerase chain reaction for a given molecule of DNA, we need primers. Primers can only be designed only if we know the sequence of the region of interest. The sequence of the region of interest can be known only if the gene has already been cloned and sequenced.

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