Balance the tubes by adding isopropanol or extraction buffer. Produce a pellet of DNA by centrifuging at 15,000 rpm for 15 min. Gently pour off the supernatant and lightly dry the pellets by inverting the tubes on paper towels for 1-2 min.
Onions not only provide flavor, they also provide important nutrients and health-promoting phytochemicals. High in vitamin C, onions are a good source of dietary fiber, and folic acid. They also contain calcium, iron, and have a high protein quality (ratio of mg amino acid/gram protein). Onions are low in sodium and contain no fat. Onions contain quercetin, a flavonoid (one category of antioxidant compounds).
1 The health benefits of onions are starting to look quite appealing. 2  Osteoporosis â In a 2005 study, researchers found that a compound in onions, GPCS, was able to decrease bone loss in rats, helping to prevent osteoporosis.