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).
Related to Diet & Weight Management. Onions: Full of Nutrients. These members of the allium genus deliver plenty of health benefits. Peel away the skin of this vegetable to find whole layers of health benefits. Worshiped by the Egyptians as far back as 3500 B.C., the onion symbolized eternity because of its concentric-circle construction.