The Processes of Gluconeogenesis and Glycolysis Paper Example

1) How are gluconeogenesis and glycolysis regulated reciprocally?

The processes of gluconeogenesis and glycolysis are related in a reciprocal fashion where one path is relatively inactive while the other is highly active and with both being highly exergonic. At high energy charge, it is not necessary for the cell to produce any more ATP meaning that the glucose is turned off via the allosteric inhibition of hexokinase and pyruvate kinase by specific allosteric effectors.

Is your time best spent reading someone else’s essay? Get a 100% original essay FROM A CERTIFIED WRITER!

Save 25%

2) How does citrate influence glycolysis?

Citrate is the first product of the citric acid cycle. Build up of citrate means that glycolysis can slow down and this means that citrate influences the glycolysis by helping in the process of breaking down glucose into two molecules of pyruvate. Citrate inhibits PFK-1 when glycolysis is highly active and this means that citrate is abundant and has an inhibitory effect on the pathway. Citrate accumulation usually depends on the glycogenolysis implying that an active glycolysis to generate pyruvate for citrate synthesis. As the citrates influence glycolysis, phosphofructokinase is inhibited by citrate which is an intermediate in the citric acid cycle. In most cases when citrate is high, the enzyme is inhibited, and fewer glucose molecules are metabolized. In this sense, citrate serves as a cell indicator. When the biosynthetic precursor is abundant, it means that there are high levels of citrate in the cytoplasm which also means that there would be no need to degrade additional glucose, especially for this purpose.

3) What are glucose transporters and how do the different types of transporters differ?

Glucose transporters are large proteins that weave in and out of the membrane 12 times to form stereospecific channels through which glucose can diffuse down its concentration gradient. These transporters usually differ in terms of their substrate specificity, distribution and regulatory mechanisms. These transporters can also be considered to differ in the types of diseases they cause as they have received much attention as therapeutic targets for various diseases. Glucose molecules enter into the cells is mainly affected by a large family of the structurally related transport proteins and are the ones referred to as the glucose transporters. Glucose transporters are usually of two main types that include the facilitated diffusion glucose transporters and sodium-glucose linked transporters.

4) What are the key glycolytic enzymes and why are they considered key? How are these steps overcome in gluconeogenesis?

The key glycolytic enzymes include pyruvate kinase, pyruvate carboxylase and phosphoenolpyruvate kinase. They are considered to be key because they catalyze the transfer of a phosphoryl group from ATP to an acceptor. Biochemical details of gluconeogenesis are never similar with those of glycolysis, and therefore in order to overcome the steps, gluconeogenesis needs to bypass the energetically favourable steps of glycolysis which include the glucose-glucose -phosphate, fructose -phosphate (F6P) fructose 1,6-bisphosphate (F1,6BP), and phosphoenolpyruvate (PEP) pyruvate.

5) Why is it more sensible for phosphofructokinase, rather than hexokinase, to be an important control step?

Glucose-6-phosphate which is a product of hexokinase cannot be used as an intermediate in glycolysis rather can be used for other pathways such as forming glycogen. PFK is an important control step because of its product, fructose-1,6-bisphosphate which is usually irreversible and therefore considered a committed pathway in glycolysis. In metabolic processes, enzymes that catalyze these committed steps are more regulated.