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Did you know?

Before a vaccine is licensed in the USA, the Food and Drug Administration (FDA) reviews it for safety and effectiveness. The CDC then reviews all studies again, as well as the American Academy of Pediatrics and the American Academy of Family Physicians. Every lot of vaccine is tested before administration to the public, and the FDA regularly inspects vaccine manufacturers' facilities.

Did you know?

When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.

Did you know?

A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.

Did you know?

The most destructive flu epidemic of all times in recorded history occurred in 1918, with approximately 20 million deaths worldwide.

Did you know?

There are 20 feet of blood vessels in each square inch of human skin.

The double-helix structure of DNA. The double-helix structure of DNA.
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Video: Transcription - Introns and exons

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