Each Cycle of PCR Doubles the Amount of DNA Synthesized

Short Answer

Each cycle of PCR doubles the amount of DNA synthesized in the previous cycle. A pair of primers is used to direct the specific synthesis of a desired DNA segment. The following diagram shows the products of PCR amplification after three cycles. The DNA strands of the desired segment are indicated in yellow boxes in the diagram. As shown, at the end of the third cycle, 8 out of 16 strands have the desired length and are boxed. After four more cycles (i.e. at the end of the seventh cycle), how many strands of DNA are expected to be synthesized? How many of them have the desired length? Write down the two numbers and separate them with a comma, e.g. 16,8.