qPCR simulator: call the round
Three tubes, 35 rounds of copying and a glow that builds up. Read the curves and call the round where each one is a quarter of the way up.
Call the round
I use qPCR to estimate how much more copying a DNA library needs before sequencing. You'll watch a dye glow as DNA builds up. In this game, call the first round that reaches a quarter of each curve's rise. In the lab, I choose the cycle count using the library prep method and quality checks.
What this simulates
What you do
You start the run and watch the machine step through 35 rounds. Each round splits the DNA, lets short pieces bind and copies it, while three tubes glow more as DNA builds up: two antibody samples, A and B, and a no-antibody control. The glow is drawn as three curves.
When the run ends, you pick a tube and click or drag on the chart, or use the arrow keys, to mark the round where its curve is a quarter of the way up. A guide line shows that level. Each round you are off costs 20 points, and the game then comments on what your no-antibody control did.
The real technique
Quantitative PCR, or qPCR, copies DNA in repeated cycles: the strands are split at 95 °C, short primers bind at 60 °C and the DNA is copied at 72 °C. A dye glows more as DNA accumulates. Early on, the amount can roughly double each round. Later the curve levels off. Real analysis software usually reports the cycle where the signal crosses a threshold, called Cq or Ct. The earlier a curve rises, the more starting material there was.
I use qPCR to estimate how much more copying a DNA library needs before sequencing. The no-antibody control shows how much background there is. Calling a quarter of the rise is a simple rule for the game. The curves, the scores and the numbers are synthetic and made up for play, and nothing here comes from a real instrument.
What you learn
How to read an amplification curve, why an earlier rise means more starting DNA, and why a control runs next to the samples. If the control rises close to the samples, that is a warning about background, although the curve alone can't say what caused it.