AP Bio: Cellular Respiration VS Photosynthesis

A simplified version of the process of photosynthesis.  (This picture was taken from this site:  http://mrskingsbioweb.com/Biology.html.)

Photosynthesis
6CO₂ + 6H₂O + energy -> 6O₂+ C₆H₁₂O₆
Photosynthesis is the process that converts the energy from sunlight to the glucose, which is stored as organic molecules.  This is a process that takes place inside photosynthetic organisms.  These autotrophs, or self-feeding organisms, use the process to convert light energy/sunlight into glucose (sugar) to use for food/energy.  The process of photosynthesis includes the light dependent reactions, the Calvin Cycle (dark reactions), and the electron transport chain (ETC).  The light dependent reactions and the ETC (the first part of photosynthesis) occurs in the thylakoid membranes, water and light is absorbed.  NADPH provides the energy for the reaction to occur.  Oxygen, ATP, and NADPH is produced.  In the second part of photosynthesis (the Calvin cycle), ATP, NADPH, and CO2 is used to produce sugars and NADP+.  Th NADP+ is reused in the light dependent reactions.

A simplified version of the process of cellular respiration.  (This picture was taken from this site: http://www.hyperbaric-oxygen-info.com/aerobic-cellular-respiration.html.)

Cellular Respiration
6O₂ + C₆H₁₂O₆ --> 6H₂O + 6CO₂ + energy
Unlike photosynthesis, cellular respiration converts the stored organic molecules of glucose into energy.  It includes glycolysis, the Krebs Cycle, and the electron transport chain (ETC).  in glycolysis, the reactants are glucose and the products are some ATP electrons and pyruvic acid.  This occurs in teh cell's cytoplasm.  The pyruvic acid is sent to the mitochondria, where it goes through the Kerbs cycle.  More ATP is formed, and electrons carried the NADH and FADH2 are sent to the ETC.  The ETC is in a mitochondrial membrane and has a mechanism called chemiosmosis.  At the end of the ETC, a hydrogen gradient is created by proton-motive force as the hydrogen ions move across the mitochondrial membrane into the cell and a phosphate is added to adenine diphosphate to produce adenine triphosphate (ATP).  ATP provides for most of the energy used by the cell.


Source: Campbell and Reece's Biology, Sixth Edition