(Solved): 1. Identify AND summarize the 4 metabolic pathways in producing ATP (Glycolysis, Acetyl CoA,TCA,ETC ...

Expert Answer

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1. Metabolic Pathways for ATP Production:

a. Glycolysis: It takes place in the cytosol of the cell. It breaks down glucose into two pyruvate molecules, which produces a net gain of two ATP molecules.

b. Acetyl CoA: It takes place in the mitochondrial matrix. It converts pyruvate into acetyl-CoA, which enters the TCA cycle. It produces a small amount of ATP, CO2, and reducing agents such as NADH and FADH2.

c. TCA Cycle: It takes place in the mitochondrial matrix. It oxidizes acetyl-CoA to CO2, which produces reducing agents NADH and FADH2, which are used in the ETC to produce ATP. It also produces a small amount of ATP directly.

d. Electron Transport Chain (ETC): It takes place in the inner mitochondrial membrane. It uses the reducing agents produced in the TCA cycle to generate a proton gradient, which is used by ATP synthase to produce ATP. The final electron acceptor is oxygen, which produces water.

e. Entry Points of Macronutrients: Carbohydrates enter the glycolysis pathway, fatty acids enter the beta-oxidation pathway to produce acetyl-CoA, and amino acids enter various pathways depending on whether they are glucogenic or ketogenic.

d. Coenzymes: NAD+, NADH, FAD, FADH2 are important coenzymes in these pathways. They act as electron carriers and are involved in redox reactions.

e. Significance of Acetyl CoA: Acetyl-CoA is a gateway molecule that connects glycolysis, beta-oxidation, and amino acid metabolism to the TCA cycle. It is a central molecule in energy metabolism and plays a key role in regulating the balance between carbohydrate and fat metabolism.

2. Absorptive and Post-Absorptive States:

a. Role of Macronutrients: In the absorptive state, carbohydrates are primarily used for energy, and excess is stored as glycogen. Fats are stored as triglycerides, and amino acids are used for protein synthesis. In the post-absorptive state, glycogen is broken down into glucose, and fats are broken down into fatty acids and ketones, which can be used for energy. Amino acids can also be converted to glucose via gluconeogenesis.

b. Significance of Ketosis and Ketones: Ketosis is a metabolic state where the body uses ketones for energy instead of glucose. It occurs during prolonged fasting or low-carbohydrate diets. Ketones can be used by the brain for energy and spare muscle protein from being broken down for energy.

3. Terms:

- Glycogenesis: The process of synthesizing glycogen from glucose.
- Lipogenesis: The process of synthesizing fatty acids from acetyl-CoA.
- Gluconeogenesis: The process of synthesizing glucose from non-carbohydrate sources such as amino acids or fatty acids.
- Glycogenolysis: The breakdown of glycogen to glucose.
- Lipolysis: The breakdown of triglycerides to fatty acids and glycerol.
- Glucogenic vs. Ketogenic Amino Acids: Glucogenic amino acids can be converted to glucose via gluconeogenesis, while ketogenic amino acids are converted to acetyl-CoA and ketone bodies.
- Oxidative Phosphorylation and ATP Synthase: Oxidative phosphorylation is the process of generating ATP from the electron transport chain by using the proton gradient to power ATP synthase.
- Anaerobic vs. Aerobic: Anaerobic metabolism occurs in the absence of oxygen, while aerobic metabolism requires oxygen.
- Anabolic vs. Catabolic

Anabolic refers to the building up of molecules or tissues in the body, such as the synthesis of proteins or the storage of energy in the form of glycogen or fat. Catabolic refers to the breaking down of molecules or tissues in the body, such as the breakdown of glycogen or fat to release energy.