Question

1-Select the steps of glycolysis that are downregulated by ATP. Group of answer choices

Fru 6-PO4 --> Fru-1,6-PO4

GA-3-P --> 1,3-bisphosphoglycerate

Phosphoenol pyruvate --> Pyruvaate

Glc --> Glc-6-PO4

2-

Which best describes the effect of AMP?

Downregulates Glycolysis

Upregulates Gluconeogenesis

Upregulates Glycolysis

Upregulates Gluconeogenesis & Downregulates Glycolysis

Downregulates Gluconeogenesis

Downregulates Gluconeogenesis & Upregulates Glycolysis

Answer 1

1) The steps of glycolysis that are down regulated by ATP are:

Fructose 6- phospahte to Fructose 1,6 phosphate and Phosphoenol pyruvate to Pyruvate.

The ATP (Adenosine triphosphate) is energy currency of cell. Cells produce energy when it is required to perform different kind of functions. Glycolysis is a metabolic pathway which involves breakdown of glucose to generate energy and provide intermediate molecule for cellular respiration. Fructose 6- phospahte to Fructose 1,6 phosphate is the key step in the glycolysis. When the number of ATP molecules increases in the cells then cell senses that there is no more requirement of more energy ( energy of cell can be calculated from ATP/ADP and AMP ratio) so in order to stop further production of ATP, ATP act as a regulator for enzyme phosphofructokinase (PFK) which catalyzes the Fructose 6- phospahte to Fructose 1,6 phosphate step of glycosis. ATP acts as a negative regulator of this enzyme by increasing Km value or affinity of the enzyme for Fructose 6- phospahte. The ATP act as a negative regulator of pyruvate kinase as well, an enzyme which catalyzes Phosphoenol pyruvate to Pyruvate reaction of glycolysis in the same manner as of PFK.

2) The best effect of AMP is:

Downregulates gluconeogenesis and upregulates glycolysis.

Increase in the AMP molecules in the cell shows low energy and cells require more energy in terms of ATP to do their function. Gluconeogenesis is a biosynthetic process which synthesize glucose molecule from other non carbohydrate sources. It is a energy costing process. Whereas glycolysis is just reverse of gluconeogenesis, it metabolizes glucose to generate energy in the form of ATP. When inside the cell number of AMP molecule is high, it act as a positive regulator for glycolysis enzyme PFK which catalyzes regulatory step of glycolysis. AMP and ATP compete for PFK enzyme. When Cells are low in energy, AMP binds with PFK and act as a positive regulator for enzyme which upregulates the glycolysis pathway. At the same time AMP inhibits fructose 1,6 bisphosphatase an enzyme of gluconeogenesis which works just opposite to PFK. Fructose 1,6 bisphosphate which is the product of PFK catalyzed reaction also activates phosphofructokinase therefore upregulate the glycolysis