You have a small gene that you want replicated by PCR. You add fluorescent dye-labeled nucleotides to the PCR thermal cycler. After three replication cycles, what percentage of the DNA single strands will fluoresce?
a. 0%
b. 12.5%
c. 50%
d. 87.5%
e. 100%

Verified step by step guidance

1. <insert step 1> Start by understanding the PCR process: PCR (Polymerase Chain Reaction) is a method used to amplify a specific segment of DNA. It involves repeated cycles of denaturation, annealing, and extension.
2. <insert step 2> Recognize that in each cycle, the DNA strands are separated, and new strands are synthesized using the original strands as templates. The fluorescent dye-labeled nucleotides are incorporated into the newly synthesized strands.
3. <insert step 3> In the first cycle, the original DNA strands are used as templates, and the new strands synthesized will contain the fluorescent dye-labeled nucleotides. Therefore, after the first cycle, 50% of the DNA strands will fluoresce.
4. <insert step 4> In the second cycle, both the original and the newly synthesized strands from the first cycle serve as templates. The new strands synthesized in this cycle will also incorporate the fluorescent dye-labeled nucleotides.
5. <insert step 5> After the third cycle, calculate the percentage of DNA strands that will fluoresce by considering the exponential increase in the number of strands and the incorporation of fluorescent nucleotides in each cycle.>

Key Concepts

Polymerase Chain Reaction (PCR)

PCR is a molecular biology technique used to amplify specific DNA sequences. It involves repeated cycles of denaturation, annealing, and extension, allowing for exponential replication of the target DNA. Understanding the mechanics of PCR is crucial for predicting the outcomes of DNA replication, including the incorporation of fluorescently labeled nucleotides.

Fluorescent Dye-Labeled Nucleotides

Fluorescent dye-labeled nucleotides are modified nucleotides that emit fluorescence when incorporated into DNA strands. In PCR, these nucleotides allow for the visualization of amplified DNA. The percentage of DNA strands that fluoresce after a certain number of cycles can be calculated based on the number of strands synthesized and the nature of the labeling.

Exponential Amplification

In PCR, each cycle doubles the amount of DNA, leading to exponential growth of the target sequence. After n cycles, the number of DNA strands is 2^n. This concept is essential for determining the proportion of strands that will fluoresce after a given number of cycles, as it directly influences the total amount of labeled DNA produced.