Prokaryotic and eukaryotic cells need energy to make proteins or DNA, to move, and to grow. The energy used by the cells most commonly is supplied from ATP, adenosine triphosphate. Sets of basic, biochemical reactions are used to make this ATP, using energy captured from oxidation and glucose. The metabolic pathways that oxidize glucose to make ATP in the cell are glycolysis, the Krebs cycle, and electron transport chain.

Glycolysis, a ten-step, anaerobic, enzyme catalyzed reaction, is the first process involved in capturing the energy of glucose to make ATP. Both prokaryotic and eukaryotic cells undergo glycolysis in the cytosol of the cell. The first 5 steps of glycolysis use ATP to phosphorylate glucose, a reaction that invests ATP to drive the reaction forward. The first step has glucose enter the cell, using the enzyme hexokinase to catalyze the reaction, causing an investment of a

The second process known as the Krebs cycle, begins the aerobic processes. This is an 8-step process, which occurs in the mitochondrial matrix of eukaryotic cells. Upon entering, the 3- carbon pyruvic acid is converted to Acetyl Coenzyme A by forming a substrate complex with Coenzyme A. Essentially, this delivers the degraded pyruvate to the Krebs cycle, where it undergoes a series of reactions. During step 1, the 2-carbon acetyl fragments bond to a 4-carbon oxaloacetate, forming 6-carbon citrate. Citrate is isomerized to isocitrate, during step 2. A molecule of carbon dioxide is released from the 6-carbon isocitrate, synthesizing a 5-carbon atom. The 5-carbon compound is oxidized and NAD+ is reduced to NADH. During step 4, another molecule of carbon dioxide leaves the Krebs cycle, leaving a 4-carbon compound. This 4-carbon compound is oxidized by NAD+ being reduced to NADH, forming succinyl COA. During step 5, substrate-level phosphorylation occurs. High-energy bonds of succinyl COA are broken down. Energy is conserved in COA, but a phosphate group is displaced. The intermediate compound, guanosine diphosphate picks up this displaced phosphate group, forming guanosine triphosphate (GTP). GTP donates a phosphate group to ADP, forming ATP. During step 6, succinate, which is created due to the reaction in step 5, is oxidized to fumarate and FAD is reduced to FADH 2. During step 7, fumarate, wit

Some common words found in the essay are:
, NADH Due, Coenzyme Essentially, Fe Ubiquinone, NADH Oxaloacetate, GTP GTP, transport chain, Ubiquinone FADH2, electron transport chain, electron transport, krebs cycle, Acetyl Coenzyme, eukaryotic cells, Fe S's, glyceraldehyde phosphate, step 8, nad+ reduced nadh, reduced nadh, step 6, hydrogen ions, 2 molecules, krebs cycle electron, molecules atp synthesized, cycle electron transport,
Approximate Word count = 953
Approximate Pages = 4 (250 words per page double spaced)