1. VAMPIRES:Lets start at the beginning. Humans have blood that provides oxygen to their cells so they can function. The blood has a special part that carries the oxygen, called a heme group. The heme group is composed of a porphyrin ring and an iron molecule (Fe). A picture of the home group is shown to the left!
Now for the vampires!!! When making a heme gets messed up in the body, it results in a porphyria. There is a specific type of porphyria called "Porphyria Cutanea Tarda" that is caused by the deficiency of an enzyme that builds heme (its called uroporphyrinogen III decarboxylase FYI). This disease is thought to have lead to the myth of vampires.
Porphyria Cutanea Tarda (PCT) causes a number of symptoms. Lets go through them, shall we?
(1) Fluorescent White Teeth: Uroporphyrin, which builds up because of the enzyme deficiency, is actually fluorescent, and causes bright white teeth. The teeth (and fingernails) may also turn red from a different molecule that builds up because of this enzyme deficiency.
(2)Fear of light: The build up of the partially formed heme groups causes "skin photosensitivity" or blistering and skin damage when exposed to sunlight.
(3) Drinking blood: Thats right, one of the cures for PCT is blood. Nowadays, the blood is infused, but back in the day, these people may have drank blood, because it would tell the cells to stop making the intermediates that damage their bodies.
(4) Garlic: it is believed that garlic may contain a compound that makes porphyria worse.
(5) Pale skin: porphyria causes anemia, or low blood count. This makes people pale!
Now I did some research after class and apparently the guy who came up with this theory (David Dolphin) was wrong. Drinking blood wouldn't help the disorder, garlic does not make porphyria worse, and people with porphyria don't crave blood and wouldn't know to drink it because they probably didn't know they had the disease. But its cool to think about, and was fun to learn about in class!!!
2. Bruises and colorful breakdowns
When you get a bruise, they turn all sorts of funky colors. Here is why:
First they turn red from the damaged heme from a broken blood vessel under the skin.
Then bruises turn green from the billiverdin as the heme breaks down.
Next it turns yellow from billirubin, and stays yellow for a while until the billirubin can be sent to the liver to be broken down completely.
Heme breakdown also produces purple (porphobillinogen), brown (sterocobillin, which causes the color of feces), more yellows (urobillin in urine). Its a colorful process aparently!
(also, people like to guess what disease famous people / mythological creatures have - we have so far learned that Abe Lincoln may have had Marfan's Syndrome, and that porphyria could potentially explain werewolves too. And crazy ole King George probably had a Acute Intermittent Porphyria because his urine was purple and he was crazy - both symptoms of that type of porphyria)

