ATP is very efficient energy carrier in our cell system.

Why can we use it as an energy carrier?

Are there any other alternatives?

The system has been tested about past 4.0 2.0 billion years.

Edited January 24, 201114 yr by alpha2cen

Asking "why" regarding evolutionary processes can sometimes get you into problems. There are other energy carriers, including GTP, but ATP is the main one. Phosphorylating AMP, or more commonly ADP to make ATP is a relative simple reaction. When ATP is is hydrolyzed back to ADP, the inorganic phosphate is often donated to a protein that, when it binds, causes it to change its conformation to perform some function. For example, a membrane channel or pump can open and pass molecules into or out of a cell., or the conformational change might regulate the activity of an enzyme. SM

Which one is more important between ATP synthesis and DNA synthesis?

Structure , Energy. Which one is more important?

ATP is very efficient energy carrier in our cell system.

Why can we use it as an energy carrier?

Are there any other alternatives?

The system has been tested past 4.0 billion years.

 

The phosphoanhydride bonds of ATP are kinetically stable in water but the hydrolysis of these bonds is exothermic and yields a lot of energy per mole. Other anhydrides may yield more energy per mole but are not kinetically stable enough to exist in aqueous solution which is an obvious requirement. ATP can also be hydrolyzed twice to ADP and AMP. This offers the advantage of allowing two hydrolysese to occur on one molecule of "fuel" which is important since biological aqueous solutions are already so close to saturation.

 

I think it's also convenient that adenosine is a nucleoside incorporated in DNA; killing two birds with one stone so to speak.

Edited January 24, 201114 yr by mississippichem

In the ancient Earth much oxygen was generated by cyanobacteria.

And, mitochondria had come into the prokaryotes cell.

Why our cell use mitochondria as energy generation organelle?

Are there other microorganism which use oxygen as cell respiration medium?

Edited January 24, 201114 yr by alpha2cen

I think your looking at this problem the wrong way round....in terms of evolution, the mitochondria didn't evole specificlly to become energy generation centres for cells...that is what happened in the evolutionary process. What ever the precursors to mitochondria were obviuosly provided an efficnient way for early life to mke energy and so evolution took the lead and eventually they became what we see today.

Then from the beginning, does mitochondria use current ATP carrier(same molecular metabolism)?

Regarding the mitochondria evolution theory, it goes back to this endosymbiosis theory, in wich a single cell was fagocitated by a bigger cell, but instead of being degraded it became a sinergyc relation, in wich the fagocitated cell provided energy in exchange of protection and nutrients, also this is what it's said for chloroplasts as well, the difference lies in what kind of cells or microorganisms where fagocitated, it is said that mitochondria comes from the endocitosis of proteobacterias and the chloroplasts from the cyanobacterias, but its just a theory.

 

that's a possible explanation about why the mitochondria and the chloroplasts has its own DNA and a double membrane.

 

Regards

ATP is very efficient energy carrier in our cell system.

Why can we use it as an energy carrier?

Are there any other alternatives?

The system has been tested about past 4.0 2.0 billion years.

 

Because its essentially the same thing as a rechargeable battery. You eat some food, some energy restores the bond on the end of the ADP to make a ATP, and then whenever a microscopic cell needs some energy, it just breaks off an end of ATP which turns it to ADP where the cycle continues.

 

There are other things that can do this, but in some ways they are inefficient for cells to use. ATP is made up of all sorts of elements abundant on the surface of the Earth so its only natural that the one of the most efficient cycles would be from those. Other chemicals can give off energy when a bond is broken too, but the bond often can't be restored just by adding energy since usually the "end" is then bonded to something else which you'd need a LOT of energy to get from. Take the air you breath for example. You get energy from the oxygen, however, when you have carbon dioxide, you need a large concentration of energy or a VERY large amount of more spread out energy separate the O2 and the C from each other. Plants can do this easily because they've evolved to use medium wavelength photons from the sun which carry enough energy in a concentrated region to fuel chemical reactions that might otherwise take as much as a small flame to fuel, which obviously wouldn't be very efficient and would be hard to work around if you had to use fire.

Edited January 30, 201114 yr by steevey