Question

1) If a restriction enzyme cuts a circular DNA into five fragments, how many restriction sites are there in the DNA?

2) How many molecules of DNA will be present after 6 cycles of PCR, if you started with one double-stranded DNA molecule?

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Answer 1

Answer

1) If a restriction enzyme cuts a circular DNA into five fragments it means this circular DNA has 5 restriction site as in the case of circular DNA number of the fragment is equal to a number of the restriction site. In the case, o linear DNA five fragment will generate from four restriction sites.

Number of fragment in a circular DNA= Number of restriction sites

2) the number of DNA copies from one double strand DNA will be 2 ⁽ⁿ⁺¹⁾, where n= number of cycle.

So, After 6 cycle the copy number would be 2⁶⁺¹= 2X2X2X2x2X2X2=128