Genetics: Derive a formula for the number of copies that you should have in round x of a PCR given n copies at the start

You learned in the chapter that an STR locus is a locus where alleles differ in the number of copies of a short, tandemly repeated DNA sequence. PCR is used to determine the number of alleles present, as shown by the size of the DNA fragment amplified. In the Figure below are the results of PCR analysis for STR alleles at a locus where the repeat unit length is 9 bp, and alleles are known that have 5 to 11 copies of the repeat. Given the STR alleles present in the adults, state whether each of the four juveniles could or could not be an off-spring of those two adults. Explain your answers.

Which of the following best describes the process of DNA sequencing? a. DNA is separated on a gel, and the different bands are labeled with fluorescent nucleotides and scanned with a laser. b. A laser is used to fluorescently label the nucleotides present within the DNA, the DNA is run on a gel, and then the DNA is broken into fragments. c. Nucleotides are scanned with a laser and incorporated into the DNA that has been separated on a gel, and then the DNA is amplified with PCR. d. Fragments of DNA are produced in a reaction that labels them with any of four different fluorescent dyes, and the fragments then are run on a gel and scanned with a laser. e. DNA is broken down into its constituent nucleotides, and the nucleotides are then run on a gel and purified with a laser.

Discuss Concepts A forensic scientist obtained a small DNA sample from a crime scene. In order to examine the sample, he increased its quantity by cycling the sample through the polymerase chain reaction. He estimated that there were 50,000 copies of the DNA in his original sample. Derive a simple formula and calculate the number of copies he will have after15 cycles of the PCR.