Now this brings us to the next part - how do we go from glucose to ATP? This is achieved through the process of "oxidation" - and this is carried out through a series of metabolic pathways. Complex chemical transformations in the cell occur in a series of separate reactions to form each pathway, and each reaction is catalyzed by a specific enzyme. Interestingly, metabolic pathways are similar in all organisms, from bacteria to humans. In eukaryotes (plants and animals) many of the metabolic pathways are compartmentalized, with certain reactions occurring in specific organelles. Basically, cells trap free energy released from the breakdown (metabolism) of glucose. This energy gets trapped in the ATP as it converts from ADP to ATP by the addition of phosphate.
You can thing of the Krebs cycle as theopposite of photosynthesis: a process whichreleases energy by converting organic matter backinto carbon dioxide.I like to think of life as a giant cycle ofcarbon. The carbon begins and ends the cycle inthe form of carbon dioxide but goes through manydifferent forms and transformations along the way:photosynthesis converts the carbon dioxide intoplant matter, which is passed along the food chainas organic carbon and eventually the Krebs cycleconverts this organic carbon (which is now grassor cow or tiger or grasshopper) back into carbondioxide and the whole thing begins again.
Do all living things go through photosynthesis
We don't all do photosynthesis, but without italmost nothing would be alive. Without plantsusing light energy to make food from carbondioxide, we animals (and the fungi, and someone-celled creatures) would have nothing to eat. Without plants giving off oxygen as a waste, wecouldn't break down food to make the high-energymolecules (ATP) that keep our bodies alive. Onegood clue about whether something doesphotosynthesis is color. If a living thing isgreen or blue-green it probably doesphotosynthesis.