Questions re. respiration/metabolism

[Bio-student]

Hi everyone, just a few questions I've been wondering on...

1) Glycolysis is catalyzed by enzymes. Enzyme synthesis requires energy (presumably from glycolysis). Seems there's a bit of a chicken-and-egg situation here: I'm wondering which would've developed first and why?

2) In anaerobic conditions why did the ethanol pathway evolve in some organisms and the lactic acid pathway in others?

3) ATP provides an immediate source of energy in most metabolic processes, whereas GTP, UTP etc. are more specific in the reactions they activate--why is this?

Thanks in advance for any answers...

 

[JakeA]

I'm certainly no expert, but I'll makes some guesses.

1. I'm not sure you can talk in terms of one concept evolving first or second. "Glycolysis" is a human construct, not one in which nature said "OK, I've finished this process, now let's do the next." They probably evolved jointly with similar and mutable processes preceding both of them.

2. My guess would be environmental conditions and the nutrients/energy requirements required for different organisms.

3. Again I'll guess. ATP is probably more energy rich and harder to control. GTP is probably less energy rich but easier to control its reactions, so it's used in regulation more than energy production.

 

[quicknote]

1) The development of enzymes and the process of glycolysis likely evolved simultaneously. Enzymes are essential for catalyzing the reactions of glycolysis and providing the energy needed for enzyme synthesis. It is likely that early organisms evolved enzymes and glycolysis together as a way to efficiently convert glucose into usable energy. This allowed them to thrive and survive in their environment.

2) The evolution of different pathways in different organisms can be attributed to their unique environments and selective pressures. Anaerobic conditions, where oxygen is not present, can be found in various environments such as deep sea vents, soil, and the digestive tracts of animals. The pathways for ethanol and lactic acid production provide a way for these organisms to generate energy without the use of oxygen. The specific pathway used by an organism is likely determined by their environment and what is most advantageous for their survival.

3) The different types of nucleotide triphosphates (ATP, GTP, UTP) serve specific roles in different metabolic processes. ATP is the primary energy currency of the cell and is used in a wide range of reactions. GTP, UTP, and other nucleotide triphosphates have specific roles in processes such as protein synthesis and DNA replication. This specificity allows for more efficient and precise control of these processes. It is likely that these different nucleotide triphosphates evolved to serve different functions in the cell, rather than all being used for the same purpose.