April 10, 2018
Arrowhead Union High School
Inside of the cell, many important processes take place, including cellular respiration. There are three stages to cellular respiration, starting with GLYCOLYSIS. Glycolysis begins with just a single GLUCOSE molecule. ATP gives one of its phoshpate molecules to the glucose molecule which turns ATP -> ADP.
Cellular Respiration takes place in the mitochondria.
The new molecules are both turned into G3P moleules, which is turned into 2 PYRUVIC ACID. 4 ATP are produced during glycolysis. The pyruvate molecules go through PYRUVIC OXIDATION if oxygen is present. A carboxyl group is removed from the pyruvate molecule and is released as carbon dioxide.
If no oxygen is present then the molecule will go through lactic acid fermentation, which will produce lactic acid.
The molecule from the first step is oxidized and NAD+ accepts the electrons and forms NADH. The oxidized moleule attaches to COENZYME A to form ACETYL COA which is the start of the KREB'S CYCLE. The Krebs Cycle takes place in the Mitochondrial MATRIX. The 6 carbon molecule that is formed is CITRIC ACID.
Through the Krebs Cycle, NAD+ and FAD+ are added to the molecule and pick up electrons and turn from FAD+ -> FADH2 and NAD+ -> NADH. The final four carbon molecule can be recycled through the Krebs Cycle. 2 ATP, NADH and FADH2 are produced and carbon dioxide is released.
The NADH and FADH2 then bring their electrons to the ELECTRON TRANSPORT CHAIN which is found in the INNER MEMBRANE SPACE of the mitochondria. They give their electrons to the ETC and the energy is used to pump PROTONS out of the matrix through the INTER MEMBRANE and OUTER MEMBRANE, which forms a gradient. Protons will flow back into the matrix through an ATP SYNTHASE enzyme. Once the protons are through the enzyme, oxygen accepts electrons and takes up protons to form water. Water and 34 ATP are produced by the ETC.
In the end, 38 ATP are made from a single glucose molecule. The process of aerobic cellular respiration is extremely efficient and awesome!