can cells absorb extracellular atp?

I am not sure, but I think they cannot. Usually ATP is produced (and consumed) inside the cells.

A number of eukaryotic cells take up ATP actively. I am less sure regarding prokaryotes.

i read that atp is not very stable, how stable is atp/mg2?

i read that atp is not very stable, how stable is atp/mg2?

 

That's what I would have thought, i.e. that ATP is not stable in the extracellular environment.

 

 

 

My understanding is that ATP/ADP is purely an intracellular energy currency and that glucose is the extracelllar energy currency.

i think that sometimes cell release atp or atpmg into the extracellular, but i don't how long the atp-mg2 stays intact

That's what I would have thought, i.e. that ATP is not stable in the extracellular environment.

 

 

 

My understanding is that ATP/ADP is purely an intracellular energy currency and that glucose is the extracelllar energy currency.

 

The instability is one of the reasons why I suspect that (free-living) prokaryotes do not possess appropriate transport mechanisms. In multicellular eukaryotes it is a different thing altogether, as they basically create their own habitat (i.e. the body of the respective organism).

Also for many prokaryotes glucose is not an usable C-source, or electron donor (for energy generation) mostly due to the fact that it does not naturally exist in significant abundance in their habitats.

AFAIK Mg is only around ATP due to ionic interactions with oxygen (i.e. is not covalently bound to the ATP. Beside that ATP does hydrolyze in dependence on the environment. Since Mg2+ mask the repulsive negative charges within ATP (as mentioned before) thus stabilizing it a bit. However, it does not suddenly transform it into a absolutely stable molecule (if it was, there would not be much energy won by hydrolyzing it, anymore). The stability of ATP either with or without Mg2+ depends on a number of factors, including temperature and, ion concentration and pH.

Also for many prokaryotes glucose is not an usable C-source, or electron donor (for energy generation) mostly due to the fact that it does not naturally exist in significant abundance in their habitats.

 

I don't knowe about that.

 

Plant tissue is composed of, in large part, by cellulose.

 

Soil contains large amounts of decaying plant tissue and therefore cellulose.

 

Cellulose is composed of glucose and is broken down by a plethora of bacteria and fungi.

 

So there must be some glucose present in soils. Perhaps because soil contains so many bacteria and fungi, any glucose that is realeased from cellulose is immediately consumed and hence measurable soil glucose is always low at any one point in time.

 

When I was doing microbiology one of the key taxonomic characteristics of many bacteria and fungi (not only the medically significant species) was which disaccharides and monosaccharides they were capable of metabolising. They wouldn't have evolved such metabolism if sugars in general were not available in soils etc.

As I said, it depends on the prokaryote. The majority of anaerobic subsurface bacteria for instance utilize acetate and propionate because they are lower in the degradation chain, so to speak. Bacteria living in more biomass rich environments (including our bodies) obviously are better adapted to glucose utilization. But even there you can find differences. A number of skin-colonizing bacteria utilize fatty acids rather than C6-sugars.

I.e. even within the same overall habitat different specializations exist.

 

Edit: maybe I should be a bit more specific.

Because glucose is such a rich energy source, there is selective advantage in utilizing it. As a result once released, it will be relatively quickly utilized and will not be available in larger distances from its source. As a result, many bacteria that have not direct access to these sources (e.g. simply by living more distant to it) specialize in using degradation/fermentation compounds of these sugars as C-source and/or electron donors.

Edited July 25, 201114 yr by CharonY

As I said, it depends on the prokaryote. The majority of anaerobic subsurface bacteria for instance utilize acetate and propionate because they are lower in the degradation chain, so to speak. Bacteria living in more biomass rich environments (including our bodies) obviously are better adapted to glucose utilization. But even there you can find differences. A number of skin-colonizing bacteria utilize fatty acids rather than C6-sugars.

I.e. even within the same overall habitat different specializations exist.

 

Edit: maybe I should be a bit more specific.

Because glucose is such a rich energy source, there is selective advantage in utilizing it. As a result once released, it will be relatively quickly utilized and will not be available in larger distances from its source. As a result, many bacteria that have not direct access to these sources (e.g. simply by living more distant to it) specialize in using degradation/fermentation compounds of these sugars as C-source and/or electron donors.

 

That's interesting. I had been wondering what would happen in the soil if you sprayed the weeds with vinegar (acetate) over a long period. I presume you would get CO2 and H20 as the oxidation products of acetate.

That's interesting but if you do so, another point comes into play, the pH... So, probably before you get significant amounts of CO2 and H2O you will first observe a change in the ecosystem.

 

That's interesting. I had been wondering what would happen in the soil if you sprayed the weeds with vinegar (acetate) over a long period. I presume you would get CO2 and H20 as the oxidation products of acetate.