2. The enzyme exists in two interconvertible forms that differ markedly in their activities: Protomer (inactive) filamentous polymer (active) Citrate and isocitrate bind preferentially to the filamentous form, and palmitoyl-CoA binds preferentially to the protomer. Select the true statements that explain how these properties are consistent with the regulatory role of acetyl-CoA carboxylase in the biosynthesis of fatty acids. High citrate and isocitrate levels indicate that there is plenty of ATP, reduced pyridine nucleotides, and acetyl-CoA for fatty acid synthesis. Palmitoyl-CoA is a feedback inhibitor, driving the equilibrium in the direction of the inactive (protomer) form. Palmitoyl-CoA triggers phosphorylation to inactivate the enzyme. Citrate and isocitrate are the precursors for acetyl-CoA synthesis in the mitochondria, thus providing the starting material for fatty acid biosynthesis. The protomer and filamentous polymer are the two subunits of acetyl-CoA carboxylase that hold the biotin carrier protein, which rotates between the subunits depending on which compound is bound.
Electron Transport Chain
The electron transport chain, also known as the electron transport system, is a group of proteins that transfer electrons through a membrane within mitochondria to create a gradient of protons that drives adenosine triphosphate (ATP)synthesis. The cell uses ATP as an energy source for metabolic processes and cellular functions. ETC involves series of reactions that convert redox energy from NADH (nicotinamide adenine dinucleotide (NAD) + hydrogen (H)) and FADH2(flavin adenine dinucleotide (FAD)) oxidation into proton-motive force(PMF), which is then used to synthesize ATP through conformational changes in the ATP synthase complex, a process known as oxidative phosphorylation.
Metabolism
Picture a campfire. It keeps the body warm on a cold night and provides light. To ensure that the fire keeps burning, fuel needs to be added(pieces of wood in this case). When a small piece is added, the fire burns bright for a bit and then dies down unless more wood is added. But, if too many pieces are placed at a time, the fire escalates and burns for a longer time, without actually burning away all the pieces that have been added. Many of them, especially the larger chunks or damp pieces, remain unburnt.
Cellular Respiration
Cellular respiration is the cellular process involved in the generation of adenosine triphosphate (ATP) molecules from the organic nutritional source obtained from the diet. It is a universal process observed in all types of life forms. The glucose (chemical formula C6H12O6) molecules are the preferred raw material for cell respiration as it possesses a simple structure and is highly efficient in nature.
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