Respiration Vs Photosynthesis

There are many similarities and differences between the processes of aerobic respiration and photosynthesis. To start, aerobic respiration can be defined as a biochemical pathway through which chemical bond energy is released from food and changed into ATP. On the other hand, photosynthesis is manufacturing of carbohydrates out of CO2 and the splitting of water in the presence of light.

Photosynthesis and aer. respiration can be the same in many ways. For instance, both of them contain cycles. In photosynthesis, there is the Calvin cycle, and photosystem I, just producing ATP. In aer. respiration, there is the Kreb cycle. The equations for both of these processes are also similar, C6H12O6 + 602 --> 6CO2 + 6H2O + energy (aerobic respiration.)
The only difference is that photosynthesis uses this equation in reverse. In aer. respiration, oxygen, NAD+ and FAD+ become reduced while ADP is phosphorylated and water along with 36-38 ATP as major molecules produced. The process of photosynthesis NADP+ and CO2 are reduced while RuBP is oxidized and 2 PGAL combine to make water as its major products. Also, both of these processes are used to keep cells alive and productive. In the thylakoid membrane (photosynthesis) and the interfolded part of the mitochondrial matrix, cristea,(aer. respiration) are cytochrome chains. Oxidative phosphorylation is used to pump electrons through proteins, which indirectly causes H+ ions to be pumped across a membrane and diffuses back through causing ADP to be phosphorylated making energy in the form of ATP. In both processes, ATP and NADH are present. Also, they are both concerned with oxygen but in photo. it is given off and in respiration it is a product.

Photosynthesis when contrasted with aer.
respiration is also very different. Photosynthesis takes place in the chloroplast of plants in the thylakoids and aer. respiration occurs in the mitochondrion of cells. Both processes have different purposes starting off with saying that photosythesis's goal is to make carbohydrates, lipids, or proteins and the goal of respiration is to make ATP, water and have oxygen as the final hydrogen acceptor. There is no FADH+ in photosynthesis, a lower electron acceptor, and no photophosphorylation in aer. res. The cycles of the 2 are similar all in that there are different molecules put in and different enzymes used. In the Kreb cycle, a pyruvic acid goes from the cytosol after being formed from a split glucose molecule (glycolysis) into the matrix of the mitochondrion. There it is meet with acetyl CoA and CO2 and NADH2 is given off. The NADH2 goes straight to the E.T.C. to be used and this is not what happens in photosynthesis. After making 2 ATP, 6CO2, 8 NADH2 and 2 FADH2, the process finishes in the E.T.C. For every NADH2 dropping off its electrons there is energy to make 3 ATP. Only 2 are made from every FADH2 though. In summary, we breath so oxygen is the final electron acceptor and we exhale to alleviate wastes. In photosynthesis, there is a reaction center where there is a chlorophyll a and in photosystem I it is referred to as P700 and in photosystem II it is called P680. In photo. water is oxidized. The enzyme that differs
from the Kreb cycle, in photosynthesis, is called RuBP. It joins with CO2 and then becomes an unstable compound and splits into 2 3C molecules. Also, light is used to split water while in aer. res. H+ is added on to O2 to make water. At early photo- synthesis, light excites electrons and this gets the process in motion.