In this chapter we focused on how specific DNA sequences...

Question

In this chapter we focused on how specific DNA sequences can be copied, identified, characterized, and sequenced. At the same time, we found many opportunities to consider the methods and reasoning underlying these techniques. From the explanations given in the chapter, what answers would you propose to the following fundamental questions?

What steps make PCR a chain reaction that can produce millions of copies of a specific DNA molecule in a matter of hours without using host cells?

Accepted Answer

Hi, everybody. Let's take a look at this practice problem together which of the following describes the PCR limitation. Now, recall what PCR is and PCR is short for preliminaries chain reaction. It's a lab technique to amplify or increase the total number of copies of A D N A sample. So let's review the options. We've got B it is a time consuming and laborious technique. Now PCR is a fairly quick technique that takes approximately 45-60 minutes to complete. Therefore, option B is not a limitation. Options. See it can amplify a small amount of D N A. Only PCR can amplify small fragments of D N A and it produces exponential amounts or copies of the D N A sample. Therefore, C is also not a limitation. Then we've got D it produces errors in the amplified D N A. Now, this is not a purpose of PCR. However, with any lab technique, errors can occur, but this is not the main purpose of PCR. So D is not the correct answer either. So the limitation of PCR is that it cannot be used for RNA amplification. Now, to work around this, there is a technique which is called RT PCR or reverse transcription. PCR. In this technique, you can convert RNA into complementary DNA strand and then you can use PCR to amplify that complementary D N A sample. But PCR limitation by itself is a, it cannot be used for RNA amplification. Alright, everyone I hope you found this helpful and I'll see you soon for the next practice problem.

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