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I am currently working on a Master's Degree in Nutrition and requirements for Registered Dietician R.D. I plan to run my first full marathon in 2009. This blog is about everything I learn, eat, and do along the way. Cheers!

Thursday, November 13, 2008

Advanced Nutrient Metabolism: Pyruvate--Acetyl CoA and Pyruvate-- Lactate, Lactate Metabolism and PPP

I mentioned before , fructose ( which is excited by glucokinase in the liver) gets phosphorylated in the cell into fuctose 1-P ( using up one ATP) which then gets converted to glyceraldehyde 3-P. This glyceraldehyde is the backbones of triglycerides ( glycerol with three attached fatty acids). High fructose syrups/ high fructose intake is thought to impact this process by 1. Exciting glucokinase , stimulating the glycolysis of glucose--> pyruvate-->acetyl CoA.

Acetyl CoA is the building blocks of..... Lipids! More fat!
and 2. Fructose turning into glyceraldehydes ups your triglyceride levels- which can increase your insulin resistence - which increases insulin release- which increases blood glucose-- which means Diabetes to follow!

PPP is the pentose phosphate pathway.

We use this pathway to bar off glucose for a little while. Why you may ask? Of course, to make it into other important stuff -
1. ribose- so we can form nucleic acids , DNA... and
2. So we can make NADPH2.

NADPH2 is involved in this cute little process that lets us get rid of a free radical.. h2 O2 ..hydrgoen peroxide. If we do not get rid of it, it will cause our red blood cells to burst- Not GOOD !!

So, NADPH2 interacts with Glutathione ( 2 GSH)... which requires an enzyme ( of course!) Glutathione Peroxidase - this turns H2O2 ( the bad guy) into H2O.. water!

The PP Pathway starts with 3 molecules of glucose

glucose-6-P glucose 6-P glucose 6-P

--with the help of glucose-6-p-dehydrogenase----key enzyme (again with the enzymes)

-6phosphogluconate -6phosphogluconate-6 phosphogluconate

these each break-off Carbons as CO2 ... and Turns NADP into NADPH2 ( horrary!)

5-Carbon Compound - Ribose ( yah!) - 5 carbon Compound

These all can easily convert to...

glucose -6- P -glucose-6-P and -glyceraldehyde

All of which can go back to glycolysis or the g-6-p's can go to glycogenesis

Lactate Metabolism!

I know you all are dying to know this!

So glucose---> pyruvate ---> Acetyl CoA ( in high oxygen situations)
Well in low oxygen situations, or say high demand exercise
pyruvate---> lactate
this conversion also gives us the ultra-important taxi: NAD+

NAD+ is a taxi that goes back to the glucose stage to convert glucose--> pyruvate (aka glycolysis)

This is important in keeping us alive- without oxygen, lactate gets sent into the blood, then into the liver, then gets conerted there back to pyruvate and back to glucose- then back to the beginning of glucose.

I am done! I took my test and feel VERY good about it- keep your fingers crossed!
Thanks for reading about Nutrient Metabolism!


strongandhealthy said...

I have no clue what the heck any of that stuff means, but you really know your info!!!! haha!!!

Madison said...

ditto to strongandhealthy LOL! nutrition smarty pants =)