Wednesday, 11 April 2012

...I Have (at least) 3 Mendelian Traits.

I've mentioned this before but I'm no biology fan. I'm not saying biology as a science sucks, I just don't understand it all that well. Therefore I'm not a fan. But I try. I was watching something on DNA and Heredity and the name Gregor Johann Mendel came up. Everyone already knew that your parents would pass on certain traits to their offspring. Daughters have been looking like their mothers forever. Mendel was basically the first to come up with a scientific explanation for it.

Who's who?
It all started with his pea plants. He would cross breed different types to see what would happen. He was a monk so he had plenty of time on his hands and cross bred his plants about 29,000 times. His first clue into traits being passed on was when he was breeding plants with white and purple flowers. He thought he would get a blend of the two, a light purple, but found that 3/4 times the offspring would be a full blown purple. Since a white flower would pop out every now and then, he concluded the purple flower was dominant. We kinda know how this works, genes come in pairs and lets say the purple flower has a 'PP' gene and the white has a 'ww' gene (a capital P to show dominance). When sperm meets egg they split these pairs and the new baby randomly gets two out of the four. Either a PP, Pw, wP, or ww. Purple is dominant and results in a purple offspring 3/4 times as Mendel's experiments suggest it would.
I think I see nirvana.
A Mendelian trait is when the 'ww' shows up and its rare. Remember, any offspring only has a 1/4 chance of getting a 'ww' but a 3/4 of getting a 'P' in any combo. Plus if one parent has a PP and the other a Pw the w will always be recessive. These traits are also isolated to one specific gene. Eye colour was thought to be a Mendelian trait (I would have had 4 then...) but further study suggests eye colour involves multiple genes. Some examples of Mendelian traits are sickle-cell anemia, Tay-Sachs disease, cystic fibrosisxeroderma pigmentosa, Albinism, and immunity to poison ivy.

Fezzik, jog his memory.
The 3 I have are hitchiker's thumb (it bends backward quite a bit), photic sneeze reflex (bright light causes sneezing), and wet ear wax (wet ear wax). I might be able to smell hydrogen cyanide or taste phenylthiocarbamide but haven't had the opportunity to try yet.

Going my way?
And that is what I learned today.

-If you were to unravel all the DNA in your body, it would reach the sun and back......600 times!

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