I Have A Question About The Cell
- Thread starter Patriot
- Start date
Sure there are. Caffeine is an example, although I can't remember the exact mechanism. It's something like:
1. the cell breaks down ATP into AMP and inorganic diphosphate.
2. AMP cyclizes due to intramolecular attractions.
3. build-up of cyclic AMP (cAMP) is detected, and enzyme break the cyclization.
4. ATP is produced in response to high levels of AMP
What caffeine does is mimics cAMP, so you're cell produces large amounts of ATP, giving you energy. However, you're cell eventually notices that there isn't really any cAMP, and shuts down ATP synthesis, resulting in the 'crash' you experience after drinking a lot of coffee.
I think that's how it works, anyways.
1. the cell breaks down ATP into AMP and inorganic diphosphate.
2. AMP cyclizes due to intramolecular attractions.
3. build-up of cyclic AMP (cAMP) is detected, and enzyme break the cyclization.
4. ATP is produced in response to high levels of AMP
What caffeine does is mimics cAMP, so you're cell produces large amounts of ATP, giving you energy. However, you're cell eventually notices that there isn't really any cAMP, and shuts down ATP synthesis, resulting in the 'crash' you experience after drinking a lot of coffee.
I think that's how it works, anyways.
aaah second messenger hormones eh Idle Mind?
The answer to your question is pretty complicated, because there multiple control points. Basically ATP production is regulated by turning glucose catabolism up and down. If you study the design carefully, it makes a lot of sense and is pretty fascinating.
A cell regulates ATP production in several ways. First, it doesn't use glucose unless it needs to (It "needs to" if ATP concentrations are low, and doesn't need to if they are high.)
Glycolysis is the process of splitting glucose into 3-carbon sugars, and eventually converting those to pyruvate. It's the first step in glucose catabolism. ATP and citrate inhibit glycolysis by shutting down the enzyme phosphofructokinase-1, whereas ADP and fructose 2,6-bisphosphate stimulate glycolysis.
It makes sense that high levels of ADP would stimulate ATP production, since it's what's "left over" after ATP is hydrolyzed (usually). In a sense, ATP regulates its own production by shutting down glycolysis when it's too abundant. It's pretty cool how it works--phosphofructokinase-1 has two binding sites for ATP: one that causes it to act as a catalyst, and another that allosterically shuts down the enzyme.
Intermediate products in the metabolic pathway, such as citrate (the product of the first step of the citric acid cycle), also inhibit glycolysis. This linkage synchronizes glycolysis and the CAC.
Inside mitochondria, high levels of ATP, NADH, and acetyl CoA phosphorylate (and thereby inhibit) pyruvate dehydrogenase, which is the entry into the CAC. So high levels of any of these slow down CAC. There are also three regulated enzymes in the CAC.
So, basically, ATP production is regulated by allosteric effects that turn glycolysis and the CAC up and down in response to the need (or lack of need) for ATP.
You can read about this in some detail in the book "Molecular Cell Biology", available online at:
http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowSection&rid=mcb.section.d1e70541
Pretty cool stuff, I think!
A cell regulates ATP production in several ways. First, it doesn't use glucose unless it needs to (It "needs to" if ATP concentrations are low, and doesn't need to if they are high.)
Glycolysis is the process of splitting glucose into 3-carbon sugars, and eventually converting those to pyruvate. It's the first step in glucose catabolism. ATP and citrate inhibit glycolysis by shutting down the enzyme phosphofructokinase-1, whereas ADP and fructose 2,6-bisphosphate stimulate glycolysis.
It makes sense that high levels of ADP would stimulate ATP production, since it's what's "left over" after ATP is hydrolyzed (usually). In a sense, ATP regulates its own production by shutting down glycolysis when it's too abundant. It's pretty cool how it works--phosphofructokinase-1 has two binding sites for ATP: one that causes it to act as a catalyst, and another that allosterically shuts down the enzyme.
Intermediate products in the metabolic pathway, such as citrate (the product of the first step of the citric acid cycle), also inhibit glycolysis. This linkage synchronizes glycolysis and the CAC.
Inside mitochondria, high levels of ATP, NADH, and acetyl CoA phosphorylate (and thereby inhibit) pyruvate dehydrogenase, which is the entry into the CAC. So high levels of any of these slow down CAC. There are also three regulated enzymes in the CAC.
So, basically, ATP production is regulated by allosteric effects that turn glycolysis and the CAC up and down in response to the need (or lack of need) for ATP.
You can read about this in some detail in the book "Molecular Cell Biology", available online at:
http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowSection&rid=mcb.section.d1e70541
Pretty cool stuff, I think!