Metabolism: Anabolism & Catabolism

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Briefly describe the role of the electron transport chain in the context of the larger metabolic pathways.

The electron transport chain uses energy from electrons to pump protons and create a proton gradient. The energy in this gradient is then harvested to produce ATP, which can be used for anabolic reactions.

Explain why both anabolic and catabolic pathways are necessary for a cell's survival.

Catabolic pathways break down molecules to release energy and building blocks, while anabolic pathways use energy and building blocks to synthesize new molecules. Both are required for maintaining cellular functions, growth, and response to environmental changes.

Outline the different fates of glucose within a cell, considering both anabolic and catabolic pathways.

Glucose can be broken down for energy (glycolysis), stored as glycogen (glycogenesis), used to create 5-carbon sugars (pentose phosphate shunt), or synthesized from precursors (gluconeogenesis).

If a person is fasting and their glycogen stores are depleted, which pathway will their body primarily rely on to maintain blood glucose levels, and from what types of molecules can glucose be synthesized?

Gluconeogenesis; lactate, glycerol, and certain amino acids. Signup and view all the answers

Briefly explain the relationship between glycogenesis and glycogenolysis and why both pathways are important.

Glycogenesis is the synthesis of glycogen from glucose for storage, while glycogenolysis is the breakdown of glycogen to release glucose. These pathways allow the body to store excess glucose and release it when needed, maintaining blood sugar levels. Signup and view all the answers

Distinguish between anabolism and catabolism, emphasizing the role of energy in each process.

Anabolism is the process of building larger molecules from smaller subunits, requiring energy input. Catabolism is the breakdown of larger molecules into smaller subunits, releasing energy. Signup and view all the answers

How do NADH and FADH2 contribute to ATP production, and in what part of cellular respiration are they primarily generated?

NADH and FADH2 donate electrons to the electron transport chain (ETC), driving ATP synthesis through oxidative phosphorylation. They are primarily generated during glycolysis, the citric acid cycle, and beta-oxidation. Signup and view all the answers

Compare and contrast glycogenesis and glycogenolysis, indicating the purpose and product of each pathway.

Glycogenesis is the synthesis of glycogen from glucose for storage, while glycogenolysis is the breakdown of glycogen to glucose for energy use. Signup and view all the answers

Describe the purpose of the pentose phosphate pathway (pentose phosphate shunt), and list its major products.

The pentose phosphate pathway produces NADPH and pentose sugars. NADPH is used in reductive biosynthesis, while pentose sugars are components of nucleotides and nucleic acids. Signup and view all the answers

Explain how beta-oxidation contributes to energy production, including the substrate and major products of this process.

Beta-oxidation breaks down fatty acids into acetyl-CoA. Acetyl-CoA then enters the citric acid cycle to produce ATP, NADH, and FADH2. Signup and view all the answers

Contrast lipogenesis and lipolysis, noting the conditions under which each process is favored.

Lipogenesis is the synthesis of triglycerides from acetyl-CoA and glycerol, favored when energy is abundant. Lipolysis is the breakdown of triglycerides into glycerol and fatty acids, favored when energy is needed. Signup and view all the answers

Outline the key steps of glycolysis, indicating the starting molecule, end products, and net ATP production.

Glycolysis starts with glucose, which is broken down into two molecules of pyruvate. The net ATP production is 2 ATP molecules per glucose molecule. Signup and view all the answers

Explain why the breakdown of ATP to ADP + Pi releases energy.

The breakdown of ATP releases energy because the phosphate bonds in ATP are high-energy bonds. The release of a phosphate group relieves electrostatic repulsion and resonance stabilization. Signup and view all the answers

Briefly explain how the electron transport chain (ETC) contributes to the production of ATP.

The ETC uses electrons from NADH and FADH2 to pump H+ ions, creating a gradient. These H+ ions flow back through ATP synthase, driving ATP production. Signup and view all the answers

What is the final electron acceptor in the electron transport chain, and what molecule is formed as a result?

The final electron acceptor is oxygen. Water (H2O) is formed. Signup and view all the answers

Explain the difference between oxidative phosphorylation and aerobic respiration.

Oxidative phosphorylation is the generation of ATP via the ETC. Aerobic respiration is the breakdown of carbohydrates to produce energy via the ETC. Signup and view all the answers

Why is oxygen essential for the electron transport chain to function? What happens if oxygen is not available?

Oxygen is the final electron acceptor. Without it, the ETC backs up and stops. Signup and view all the answers

Briefly describe how NADH and FADH2 contribute to the ETC.

NADH and FADH2 donate electrons to the ETC. Signup and view all the answers

Explain how the pyruvate dehydrogenase complex links glycolysis to the citric acid cycle.

The pyruvate dehydrogenase complex converts pyruvate, produced by glycolysis in the cytosol, into acetyl-CoA in the mitochondrial matrix. Acetyl-CoA then enters the citric acid cycle. Signup and view all the answers

Describe the location of the electron transport chain (ETC).

The electron transport chain is in the inner mitochondrial membrane. Signup and view all the answers

Describe the role of oxaloacetate in the citric acid cycle, and explain what happens if its levels are insufficient.

Oxaloacetate combines with acetyl-CoA to initiate the citric acid cycle. If oxaloacetate levels are insufficient, the citric acid cycle slows down, and acetyl-CoA may be diverted towards ketogenesis. Signup and view all the answers

Explain the role of the H+ gradient in ATP production during the electron transport chain.

The H+ gradient drives ATP production by flowing through ATP synthase. Signup and view all the answers

Outline the two primary metabolic fates of glucose-6-phosphate, and explain what determines which pathway is favored.

Glucose-6-phosphate can either enter glycolysis for energy production or be directed into the pentose phosphate pathway (PPP) for NADPH and ribose-5-phosphate synthesis. The cell's energy needs and the demand for NADPH and nucleotide precursors determine which pathway is favored. Signup and view all the answers

In the absence of oxygen, cells must rely on alternative pathways to produce energy. Why can't the ETC function in anaerobic conditions?

The ETC can't function because oxygen is the final electron acceptor. Without oxygen to receive electrons, the chain is unable to continue. Signup and view all the answers

Explain how fatty acid synthesis is connected to glycolysis and the pentose phosphate pathway (PPP).

Glycolysis provides pyruvate, which is converted to acetyl-CoA (the building block for fatty acids). NADPH, generated by the PPP, supplies the reducing power needed for fatty acid synthesis. Signup and view all the answers

Describe the role of hormone-sensitive lipase in lipolysis and explain how its activity is regulated.

Hormone-sensitive lipase (HSL) hydrolyzes stored triglycerides into glycerol and fatty acids. HSL is activated by hormones like epinephrine and glucagon when energy is needed and inhibited by insulin when energy is abundant. Signup and view all the answers

What is the direct source of energy that is used to pump H+ ions into the intermembrane space during the process of electron transport?

The energy released from the passing of electrons (down the ETC) is used to pump H+ ions. Signup and view all the answers

How does blocking the function of ATP synthase affect the electron transport chain and ATP production?

Blocking ATP synthase would cause the H+ gradient to build, eventually stopping the ETC and preventing ATP production. Signup and view all the answers

Explain the significance of carnitine in beta-oxidation of fatty acids.

Carnitine acts as a carrier molecule that transports long-chain fatty acyl-CoA from the cytosol into the mitochondrial matrix, where beta-oxidation occurs. Signup and view all the answers

Describe the circumstances that lead to ketone body formation and explain why this process is important.

Ketone bodies are formed during prolonged fasting, starvation, or in uncontrolled diabetes when glucose is scarce and fatty acids are mobilized. Ketone bodies are important because they provide an alternative fuel source for the brain and other tissues. Signup and view all the answers

Explain how high levels of ATP and NADH regulate the citric acid cycle.

High levels of ATP and NADH inhibit key enzymes in the citric acid cycle, such as isocitrate dehydrogenase and α-ketoglutarate dehydrogenase. This feedback inhibition slows down the cycle to match energy production with demand. Signup and view all the answers

How does the structure of fatty acyl CoA facilitate its role in beta oxidation, and what is the significance of CoA in this process?

The CoA group in fatty acyl CoA acts as a carrier, enabling the fatty acid to be transported into the mitochondria for beta oxidation. The sulfur atom (S) in CoA is key, as it forms a thioester bond with the fatty acid, facilitating its activation and subsequent breakdown. Signup and view all the answers

In the context of energy production, explain the role of acetyl CoA in linking glycolysis and the citric acid cycle (CAC).

Acetyl CoA acts as a crucial link by carrying the two-carbon acetyl group derived from pyruvate (the end product of glycolysis) into the citric acid cycle. It combines with oxaloacetate to form citrate, initiating the cycle and enabling further oxidation to produce energy carriers like ATP, NADH, and FADH2. Signup and view all the answers

During periods of prolonged fasting, the liver converts acetyl CoA into ketone bodies. What is the purpose of this conversion, and how does it benefit other tissues in the body?

The liver synthesizes ketone bodies from acetyl CoA to provide an alternative energy source for other tissues, such as the brain and muscles, when glucose availability is limited during fasting or starvation. Ketone bodies are water-soluble and can be easily transported in the bloodstream to these tissues, where they are converted back to acetyl CoA for energy production. Signup and view all the answers

Differentiate between lipolysis and lipogenesis, indicating the substrates and products of each pathway.

Lipolysis is the catabolic process by which triglycerides are broken down into fatty acids and glycerol. Lipogenesis is the anabolic process by which fatty acids are synthesized from acetyl CoA and then esterified with glycerol to form triglycerides. Signup and view all the answers

Explain why both fatty acid synthesis and beta-oxidation are essential pathways in cellular metabolism. What would be the consequence of a defect in either pathway?

Fatty acid synthesis is critical for storing excess energy as lipids, while beta-oxidation is crucial for breaking down fatty acids to produce energy when needed. A defect in fatty acid synthesis would impair the ability to store energy, leading to energy deficits. A defect in beta-oxidation would prevent the breakdown of stored fats, causing energy deficiency and lipid accumulation. Signup and view all the answers

Describe the role of phospholipids and the pathway by which they are created.

Phospholipids are crucial components of cellular membranes, providing structural integrity and regulating membrane fluidity. They are synthesized from fatty acids via a pathway called phospholipid synthesis. This pathway utilizes fatty acids to create phospholipids. Signup and view all the answers

How are fatty acids transported from the cytoplasm into the mitochondria for beta-oxidation, and what derivative of fatty acids is involved in this transport?

Fatty acids are transported into the mitochondria as fatty acyl CoA. The CoA group is attached to the fatty acid in the cytoplasm, which facilitates its transport across the mitochondrial membranes. Signup and view all the answers

Explain the process of ketolysis and the situations in which it becomes particularly important.

Ketolysis is the process by which extrahepatic tissues break down ketone bodies to release acetyl CoA, which can then be used in the citric acid cycle for energy production. Ketolysis becomes particularly important during periods of prolonged fasting, starvation, or in individuals with uncontrolled diabetes, when glucose availability is limited, and other tissues must rely on ketone bodies for energy. Signup and view all the answers

Besides energy production, what is one purpose of glucose metabolism, and what is the resulting product?

Production of 5-carbon sugars for nucleotide synthesis. Signup and view all the answers

Which metabolic pathways are responsible for storing excess glucose and fatty acids, respectively? What are the resulting storage molecules?

Glycogenesis (glucose to glycogen) and triglyceride synthesis (fatty acids to triglycerides). Signup and view all the answers

During periods of fasting, the body breaks down stored fuel. What are the pathways that break down glycogen and triglycerides called?

Glycogenolysis and lipolysis. Signup and view all the answers

Besides glycolysis, name two metabolic pathways discussed that generate NADH.

Fatty acid oxidation (beta-oxidation) and the conversion of pyruvate to acetyl CoA. Signup and view all the answers

The liver plays a central role in supplying energy to other tissues. Which metabolic pathway is predominantly performed in the liver to supply glucose to the rest of the body?

Gluconeogenesis. Signup and view all the answers

Name two pathways that result in the production of acetyl CoA. From what starting material does each pathway derive acetyl CoA?

Fatty acid oxidation (fatty acids) and pyruvate decarboxylation (pyruvate). Signup and view all the answers

Acetyl CoA feeds into what energy-producing pathway? What vitamin is required to form CoA?

Citric Acid Cycle (Krebs Cycle); Pantothenic acid (Vitamin B5). Signup and view all the answers

The electron transport chain (ETC) relies on two key energy intermediates to function. What are these intermediates, what vitamins are they derived from, and where is the ETC located?

NADH (niacin/vitamin B3) and FADH2 (riboflavin/vitamin B2); inner mitochondrial membrane. Signup and view all the answers

Flashcards

Anabolism

Metabolic pathways that build larger molecules from smaller subunits, requiring energy.

Catabolism

Metabolic pathways that break down larger molecules into smaller units, releasing energy.

Glycolysis

A catabolic pathway that converts glucose into pyruvate, producing ATP and NADH.

ATP

A high-energy molecule used as an energy currency in cells, composed of adenine, ribose, and three phosphate groups.