Big+Idea+5


 * Big Idea 5: Cellular Respiration (Aerobic)**

__Summary__ Cellular respiration is the set of metabolic reactions and processes that take place within an organism's cells to convert biochemical energy into andenosine triphosphate (ATP) and the release of waste products. The processes involved are catabolic reactions (metabolic reactions that break down molecules into smaller units and releases energy) that involve the oxidization of one molecule and the reduction of another.

Common nutrients used are: glucose, amino acids and fatty acids, and a common oxidizing agent is molecular oxygen.

The energy released during respiration is used to synthesize ATP to store this energy.

//Words with a * after them: refer to notes at bottom of page//

Aerobic respiration requires oxygen to to generate energy (ATP). This is the preferred method of pyruvate* breakdown from glycolysis. This requires the pyruvate to enter the mitochondria to be fully oxidized by the Krebs Cycle.

__Glycolysis__ Glycolysis is the metabolic pathway that converts glucose, C6H12O6, into pyruvate, C3H3O3. The energy released is used to form ATP and NADP. There are ten steps in glycolysis.

The first 5 steps are investment steps, which require consumption of energy to convert glucose into two three-carbon sugar phosphates.

The first step is the phosphorylation of glucose by enzymes to form glucose-6 phosphate. Although this consumes ATP, it ensures that the glucose concentration remains low, allowing a constant flow of glucose across the plasma membrane. Glucose 6-phosphate is then rearranged into fructose 6-phosphate by an enzyme called glucose phosphate isomerase. Although this reaction is reversible, it is generally pushed forward as the next step of glycolysis constantly consumes fructose 6-phosphate.

__Krebs Cycle__ The citric acid cycle, also called the Krebs Cycle, is a series of enzyme catalyzed* chemical reactions in all living cells that use oxygen as a part of cellular respiration. In eukaryotes, this takes place in the mitochondria.

__Notes__