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Offline omid

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Questions bothering omid.
« on: 03/10/2009 14:13:45 »
Hey guys the other day I was reading the paraghraph below from a scientific wesite
 
"Confusingly and paradoxically, chemists number the carbon atoms in a fatty acid from the carboxyl group calling the carboxyl carbon: carbon 1, whereas biologists number them from the opposite end.
Chemists     12  11  10   9   8   7   6   5   4   3   2   1  
              C — C — C — C — C — C — C — C — C — C — C — COOH
Biologists    1   2   3   4   5   6   7   8   9   10  11  12
Humans lack the enzyme needed to catalyze the introduction of a double bond into the hydrocarbon chain after carbon 9 (chemically speaking), i.e. they cannot oxidize carbon atoms beyond this. Fatty acids with a double bond here are therefore called essential fatty acids.
The last carbon in the hydrocarbon chain of a fatty acid is sometimes called the omega (ώ) carbon but if there is a double bond between carbons 3 and 4 (biologically speaking), the fatty acids is called an ώ-3 fatty acid. Some research suggests that low levels of ώ-3 fatty acids relative to ώ-6 fatty acids increase the likelihood of certain diseases. The tration in western diets is about 1 : 10.
To raise the melting point of naturally occurring unsaturated fatty acids, which all have the cis configuration, they are partially hydrogenated,i.e. reduced. Though this maked them less fluid, it creates “trans fats”, which also appear to increase the risk of certain disease.
"

After reading it these were the questions that comes to my mind

1)What name is given to the fatty acid that can’t be synthesized and must be present in the diet?
2)Can the body synthesize the ώ-9 fatty acid?
3)Where is the double bond in an ώ-6 fatty acid?
4)Why is the introduction of a double bond into a daturated fatty acid called oxidation?




 

Offline Bored chemist

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Questions bothering omid.
« Reply #1 on: 03/10/2009 16:50:46 »
The biologists warn you that they are doing something odd by calling the last carbon Omega (after the last letter of the Greek alphabet) and counting from there.
There's a reason for this- biology can add or subtract pairs of carbon atoms from the "acid" end of the molecule.
So biology can convert a C12 acid into a C10 or C14 acid if it wants. What it can't easily do is mess about with the location of the double bonds so if, for example, there's a double bond three carbons in from the end it usually stays there.

Anyway, to get to the questions
"1)What name is given to the fatty acid that can't be synthesized and must be present in the diet?"
There are several but they fall into two groups; the omega minus 3 and omega minus 6 acids.

"2)Can the body synthesize the ώ-9 fatty acid?"
Sorry, I don't know but that article you quoted suggests it can.

"3)Where is the double bond in an ώ-6 fatty acid?"
Between the sixth and seventh carbons from the end.

"4)Why is the introduction of a double bond into a saturated fatty acid called oxidation?"
One of the definitions of oxidation is the removal of hydrogen (though this gets confusing in some cases).
Equivalently you can imagine that the two hydrogens which are removed are combined with an oxygen atom to give water. The details will be complicated, but that will be the overall effect.
 

Offline omid

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« Reply #2 on: 04/10/2009 13:21:52 »
Wow!!!!!!! :o
Thanks Bored Chemist
Omid guess sometimes BORED chemist's answers are really cool ;)
 

Offline RD

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« Reply #3 on: 05/10/2009 21:51:18 »
 

Offline Bored chemist

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« Reply #4 on: 06/10/2009 19:29:33 »
LOL.
 

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Questions bothering omid.
« Reply #4 on: 06/10/2009 19:29:33 »

 

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