Primers are necessary when running a PCR reaction, which should generally have the following properties:
- Length of 18-24 bases.
- 40-60% G/C content.
- Start and end with 1-2 G/C pairs.
- Melting temperature (Tm) of 50-60°C.
- Primer pairs should have similar Tm, within 5°C of each other.
- Primer pairs should not have complementary regions.