Answer to Question #184814 in Biochemistry for Emmers Occean

Question

Indicate the impact on metabolic processes, super high [regulatory molecule] will have on: glycolysis, gluconeogenesis, pyruvate oxidation, citric acid cycle, electron transport chain, oxidative phosphorylation, glycogen, lipid, and amino acid metabolism. Support your response by summarizing why this impact would be observed.

Answer 1

Glycolysis is the metabolic pathway that converts glucose C₆H₁₂O₆, into pyruvate, CH₃COCOO⁻, and a hydrogen ion, H⁺. The free energy released in this process is used to form the high-energy molecules ATP (adenosine triphosphate) and NADH. Glycolysis is an oxygen-independent metabolic pathway. The wide occurrence of glycolysis indicates that it is an ancient metabolic pathway.

Gluconeogenesis (GNG) is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. It is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms. In vertebrates, gluconeogenesis occurs mainly in the liver and, to a lesser extent, in the cortex of the kidneys. It is one of two primary mechanisms – the other being degradation of glycogen (glycogenolysis) - used by humans and many other animals to maintain blood glucose levels, avoiding low levels (hypoglycemia).

Pyruvate oxidation is the step that connects glycolysis and the Krebs cycle.^[3] In glycolysis, a single glucose molecule (6 carbons) is split into 2 pyruvates (3 carbons each). Because of this, the link reaction occurs twice for each glucose molecule to produce a total of 2 acetyl-CoA molecules, which can then enter the Krebs cycle.

The citric acid cycle (CAC) – also known as the TCA cycle (tricarboxylic acid cycle) or the Krebs cycle– is a series of chemical reactions used by all aerobic organisms to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. 

The flow of electrons through the electron transport chain is an exergonic process. The energy from the redox reactions create an electrochemical proton gradient that drives the synthesis of adenosine triphosphate (ATP). In aerobic respiration, the flow of electrons terminates with molecular oxygen being the final electron acceptor. 

Oxidative phosphorylation  is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing the chemical energy stored within the nutrients in order to produce adenosine triphosphate (ATP). 

With a lack of glucose in the body, glycogen is broken down by enzymes into glucose, which enters the bloodstream. Regulation of the synthesis and breakdown of glycogen is carried out by the nervous system and hormones. Hereditary defects in enzymes involved in the synthesis or cleavage of glycogen lead to the development of rare syndromes - glycogenosis.

Lipid metabolism is the synthesis and degradation of lipids in cells, including the breakdown or storage of fats for energy and the synthesis of structural and functional lipids, such as those involved in building cell membranes.

Amino acids

In humans, non-protein amino acids also have important roles as metabolic intermediates, such as in the biosynthesis of the neurotransmitter gamma-aminobutyric acid (GABA). Many amino acids are used to synthesize other molecules, for example:

• Tryptophan is a precursor of the neurotransmitter serotonin.^[76]
• Tyrosine (and its precursor phenylalanine) are precursors of the catecholamine neurotransmitters dopamine, epinephrine and norepinephrine and various trace amines.
• Phenylalanine is a precursor of phenethylamine and tyrosine in humans. In plants, it is a precursor of various phenylpropanoids, which are important in plant metabolism.
• Glycine is a precursor of porphyrins such as heme.
• Arginine is a precursor of nitric oxide.
• Ornithine and adenosylmethionine are precursors of polyamines.
• Aspartate, glycine, and glutamine are precursors of nucleotides. However, not all of the functions of other abundant nonstandard amino acids are known.