Glycolysis Case

Essay #4

Your fourth essay is due by midnight on Saturday, July 23. In your essay, please answer these 2 questions from Lesson 7 and Lesson 8:

From Lesson 7: Question 4 - For a long time there were only two kingdoms, plants and animals. Why was it necessary to create more kingdoms?

From Lesson 8: Question 4 - Some scientists argue that glycolysis was the first metabolic pathway to evolve. What kinds of evidence are used to support this argument?

Glycolysis is a metabolic pathway that is found in the cytoplasm of cells in all living organisms and does not require oxygen. The process converts one molecule of glucose into two molecules of pyruvate, and makes energy in the form of two net molecules of ATP. Four molecules of ATP per glucose are actually produced; however, two are consumed for the preparatory phase. The initial phosphorylation of glucose is required to destabilize the molecule for cleavage into two triose sugars. During the pay-off phase of glycolysis, four phosphate groups are transferred to ADP by substrate-level phosphorylation to make four ATP, and two NADH are produced when the triose sugars are oxidized. Glycolysis takes place in the cytoplasm of the cell. The overall reaction can be expressed this way:

Glucose + 2 NAD+ + 2 Pi + 2 ADP → 2 pyruvate + 2 NADH + 2 ATP + 2 H2O

Krebs cycle) is a series of enzyme-catalysed chemical reactions of central importance in all living cells that use oxygen as part of cellular