Question

Scientists have reportedly isolated short fragments of DNA from fossilized dinosaur bones hundreds of millions of years old. The technique used to isolate this DNA is the polymerase chain reaction, which is capable of amplifying very small amounts of DNA a million fold (see Chapter 19). Critics have claimed that the DNA isolated from dinosaur bones is not purely of ancient origin but instead has been contaminated by DNA from present-day organisms such as bacteria, mold, or humans. What precautions, analyses, and control experiments could be carried out to ensure that DNA recovered from fossils is truly of ancient origin?

Answer 1

Answer: If there is contamination in the DNA from one or more organisms, then the amplification of DNA of a specific organism is with the help of sequence-specific primers. Every organism has some unique sequence in their genome, that unique sequence is used for the amplification. Complementary of that unique sequence as a primer is used for amplification. The amplified product will be only of that specific organism. In this case, the primers specific for Dinosaur can be used to amplify only the DNA sequence-specific for Dinosaur.