samera
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Some body please help me...I have a problem, I have my first year PhD viva, and ive developed alot of confusion about a topic I though I knew...after a discussion with my supervisor. Now This is my problem:
The glyoxylate cycle in present in organisms such as filamentous fungi, bacteria etc so grow when acetate, ethanol, or other fatty acids are used sole carbon sources. These organisms can survive without glucose. Now how it works out is that from just 2 carbons (acetate) you get succinate to keep the TCA cycle going, and malae to make oxoloacetae to make glucose. I understand that when 2 carbons enetr 2 are lost as CO2, so there is no net synthesis. This is the bit I dont understand:
If hwen glucose i present it still has to be turned to acetyl CoA and lose 2C then isnt that the same as not having glucose. Is the TCA cycle still operating while the glyoxylate cycle is in action. Or is it that there is no glucose...so in order to make glucose the organism goes through the glycoxylate cycle to continue teh TCA cycle and produce glucose....ahhhhh i cant figure it out...or am I just digging myself into a deep hole out of frustration? somebody help it will be greatly appreciated.
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| laptop
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Be near phone.The Program director at harvard is going to call you soon.I would also like to invite you to join love island fraternity.
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| samera
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What do you mean?
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| samera
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laptop wrote:
Be near phone.The Program director at harvard is going to call you soon.I would also like to invite you to join love island fraternity.
what on earth does that mean? your not helping!!!!
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| chemamr
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 , he is just trying to help.
maybe you should post this topic in the STEP 1 FORUM. that's where it should be.
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| laptop
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Sorry samera if i offended you.I meant to say that your zeal to dissect this topic is good enough to impress the pd in harvard.It seems like that your are on track to develop the understanding of this thing but a few concepts have squared up against each other.Its common when we start reading something .I recommend that you go over full metabolism once again slowly from a good book like lippincott or one of your own choice.I would like to help you but i will have to refer back to books for that which i will happily do if you describe your problem in a bit more detail.If you wish to do that then please use other forum as i use this place as a training ground for love island fraternity members.
THanks chemamir..you are really doin a good job as a P R commandent.
over and out
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| samera
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No offence taken, thanks fo ryour help.
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| laptop
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you are welcome..hope you are able to sort it out...
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| ssrpk
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well u definitely mixing up a bit, despite the fact tht u really hv understood the cycle.....now try to interact!
TCA is a molecular m,achinery to produce ATP tht needs to functioned all the time...right!
now TCA needs substrate......which it can metabolize in order to produce ATP (via NADH/FADH2)!
acetyl CoA is the only known substrate for it.......by tht i specifically mean substrate, not intermediate!
acetyl CoA can come from different sources......from glucose [glycolysis], amino acids, proteins!
and for any cell eg.liver , before performing any specialized function it needs its own energy, therefore burning of substrates to produce ATP will be the first priority!
now, gluconeogenesis is one specialty liver deals with, but whtz the idea here, to produce and release tht glucose into the blood stream for other tissues to use (brain and rbc), while liver itself is getting its energy from anything but glucose....thts why in the face of glycolysis, gluconeogenesis shuts down.....
if glycolysis goes on, high level of ATP are produced enuff to slow down TCA, acetyl CoA builds up, gets converted into fats!
now as a switch occur, person is no more eating, but lets see in b/w meals, liver will swicth its source of energy from glucose to fats,beta oxidation produce acetyl coA, which builds up and excess produce ketones! however gluconeogenesis still goes on thru other substrates, like lactate from rbc, alanine, glycerol-PO4!
one very important point is that, in TCA substrate gets burnt up completely, in the process it borrows intermediates of TCA,but don't utilize'em! however at any point if intermediates build up, for eg. metabolism of odd chain fatty acids yeild succinyl-coA, tht intermediate can make somethng else like glucose, heme or other products, depending upon the functional status of liver which is in part dependent on the hormonal control!
i am sorry i feel like revising the stuff for myself, but i hope it helps!
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| samera
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ssrpk wrote:
well u definitely mixing up a bit, despite the fact tht u really hv understood the cycle.....now try to interact!
TCA is a molecular m,achinery to produce ATP tht needs to functioned all the time...right!
now TCA needs substrate......which it can metabolize in order to produce ATP (via NADH/FADH2)!
acetyl CoA is the only known substrate for it.......by tht i specifically mean substrate, not intermediate!
acetyl CoA can come from different sources......from glucose [glycolysis], amino acids, proteins!
and for any cell eg.liver , before performing any specialized function it needs its own energy, therefore burning of substrates to produce ATP will be the first priority!
now, gluconeogenesis is one specialty liver deals with, but whtz the idea here, to produce and release tht glucose into the blood stream for other tissues to use (brain and rbc), while liver itself is getting its energy from anything but glucose....thts why in the face of glycolysis, gluconeogenesis shuts down.....
if glycolysis goes on, high level of ATP are produced enuff to slow down TCA, acetyl CoA builds up, gets converted into fats!
now as a switch occur, person is no more eating, but lets see in b/w meals, liver will swicth its source of energy from glucose to fats,beta oxidation produce acetyl coA, which builds up and excess produce ketones! however gluconeogenesis still goes on thru other substrates, like lactate from rbc, alanine, glycerol-PO4!
one very important point is that, in TCA substrate gets burnt up completely, in the process it borrows intermediates of TCA,but don't utilize'em! however at any point if intermediates build up, for eg. metabolism of odd chain fatty acids yeild succinyl-coA, tht intermediate can make somethng else like glucose, heme or other products, depending upon the functional status of liver which is in part dependent on the hormonal control!
i am sorry i feel like revising the stuff for myself, but i hope it helps!
Basically the glyoxylate cycle carries out anapleotic reactions providng succinate for gluconeogensis, keeping the TCA cycle going. Thank you so much for your help, I understnad it now, It was for my Phd viva, which I passed!!! . The TCA cycle I was asking ab.out was in regards to filamntous fungi. But thank you so much again for all your help
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