1. Define the TCA cycle and list three phases of this pathway:
The tricarboxylic acid (TCA) cycle or the Krebs cycle is a cyclic pathway for the oxidation of acetyl residues to carbon dioxide. This cycle is crucial for metabolism, and is important for many other pathways in the body as its primary function is to provide electrons to the electron transport chain. It can be divided into three phases: Acetyl-CoA production, Acetyl-CoA oxidation, and Electron transfer/Oxidative Phosphorylation.
2. Describe the substrate(s), enzyme(s), cofactor(s), coenzyme(s), and product(s) required for each of the eight steps of the TCA cycle.(<1000 words)
Step 1: The first step of the TCA cycle begins with the substrate oxaloacetate bind to the enzyme, …show more content…
Describe different modes of regulation of TCA cycle
Regulation plays an important role in the function of the TCA cycle and is critical to maintain homeostasis. However, there is not just one way to regulate the TCA because there are so many factors that come into play. Maintaining the correct reaction rates is a crucial way the TCA cycle is regulated by ensuring enough products are formed while limiting excess production. This can be done by enzymes, allosteric effectors, and covalent modifications. The main input of the TCA cycle is Acetyl-CoA. Acetyl-CoA is regulated in 2 ways:
• Pyruvate conversion to Acetyl-CoA is regulated by the Pyruvate dehydrogenase enzyme.
• Entry of Acetyl-CoA into the TCA cycle is regulated by the citrate synthase reaction.
The production of Acetyl-CoA by the PDH complex is regulated allosterically and covalently. If ample Acetyl-CoA is present, the PDH complex is inactivated by the addition of an inorganic phosphate with the enzyme pyruvate dehydrogenase kinase. When more Acetyl-CoA is needed, the inactive complex can be reactivated by removing the phosphate with the enzyme PDH …show more content…
Describe at least 2 human disorders or defects associated with the TCA cycle.
Since the TCA cycle is such an integrated and complicated process, there are many place where something can go wrong—causing a disorder or defect in the in organism. One key location where these disorders and defects can originate is with enzymes of the TCA cycle. Mutations can occur in these enzymes that can cause harmful effects. Below are just some of the defects that are caused by the mutation of enzymes in the TCA cycle:
• A defect in the enzyme fumarase (used in step 7 of the TCA cycle to form L-Malate) may cause tumors of the kidney and smooth muscle. People with this defect have a mutation of this enzyme in each cell that impedes its ability to function properly in the TCA cycle and can result in the accumulation of fumarate. This build up can cause problems with oxygen regulation and even cause hypoxia. It is because of this that tumors may begin to form in the smooth muscle and
The tricarboxylic acid (TCA) cycle or the Krebs cycle is a cyclic pathway for the oxidation of acetyl residues to carbon dioxide. This cycle is crucial for metabolism, and is important for many other pathways in the body as its primary function is to provide electrons to the electron transport chain. It can be divided into three phases: Acetyl-CoA production, Acetyl-CoA oxidation, and Electron transfer/Oxidative Phosphorylation.
2. Describe the substrate(s), enzyme(s), cofactor(s), coenzyme(s), and product(s) required for each of the eight steps of the TCA cycle.(<1000 words)
Step 1: The first step of the TCA cycle begins with the substrate oxaloacetate bind to the enzyme, …show more content…
Describe different modes of regulation of TCA cycle
Regulation plays an important role in the function of the TCA cycle and is critical to maintain homeostasis. However, there is not just one way to regulate the TCA because there are so many factors that come into play. Maintaining the correct reaction rates is a crucial way the TCA cycle is regulated by ensuring enough products are formed while limiting excess production. This can be done by enzymes, allosteric effectors, and covalent modifications. The main input of the TCA cycle is Acetyl-CoA. Acetyl-CoA is regulated in 2 ways:
• Pyruvate conversion to Acetyl-CoA is regulated by the Pyruvate dehydrogenase enzyme.
• Entry of Acetyl-CoA into the TCA cycle is regulated by the citrate synthase reaction.
The production of Acetyl-CoA by the PDH complex is regulated allosterically and covalently. If ample Acetyl-CoA is present, the PDH complex is inactivated by the addition of an inorganic phosphate with the enzyme pyruvate dehydrogenase kinase. When more Acetyl-CoA is needed, the inactive complex can be reactivated by removing the phosphate with the enzyme PDH …show more content…
Describe at least 2 human disorders or defects associated with the TCA cycle.
Since the TCA cycle is such an integrated and complicated process, there are many place where something can go wrong—causing a disorder or defect in the in organism. One key location where these disorders and defects can originate is with enzymes of the TCA cycle. Mutations can occur in these enzymes that can cause harmful effects. Below are just some of the defects that are caused by the mutation of enzymes in the TCA cycle:
• A defect in the enzyme fumarase (used in step 7 of the TCA cycle to form L-Malate) may cause tumors of the kidney and smooth muscle. People with this defect have a mutation of this enzyme in each cell that impedes its ability to function properly in the TCA cycle and can result in the accumulation of fumarate. This build up can cause problems with oxygen regulation and even cause hypoxia. It is because of this that tumors may begin to form in the smooth muscle and