20: Energy Metabolism
- Page ID
- 15939
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Metabolism is the set of life-sustaining chemical transformations within the cells of living organisms. The three main purposes of metabolism are the conversion of food/fuel to energy to run cellular processes, the conversion of food/fuel to building blocks for proteins, lipids, nucleic acids, and some carbohydrates, and the elimination of nitrogenous wastes. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories: catabolism, the breaking down of organic matter, for example, by cellular respiration, and anabolism, the building up of components of cells such as proteins and nucleic acids. Usually, breaking down releases energy and building up consumes energy.
- 20.0: Prelude to Energy Metabolism
- This page discusses the discovery of insulin's regulatory role in glucose levels and the purification of its receptor in the early 1970s. It highlights the receptor's structure and the process by which insulin binding facilitates glucose metabolism via phosphorylation. Additionally, it explores metabolism in living organisms, detailing catabolism and anabolism, and contrasts biological respiration with combustion, stressing the importance of efficient energy utilization in cells.
- 20.1: ATP- the Universal Energy Currency
- This page explains that adenosine triphosphate (ATP) is an essential energy-rich compound in living organisms, composed of adenine, ribose, and three phosphate groups. Hydrolysis of ATP releases around 7.4 kcal/mol of energy, powering biological processes like carbohydrate synthesis and muscle contractions. ATP acts as the primary energy currency of cells, though other high-energy compounds also play a role in metabolism.
- 20.2: Stage I of Catabolism
- This page outlines the digestion process of carbohydrates, proteins, and lipids, referred to as catabolism, occurring in three stages. It describes how these macromolecules are broken down into monomers: carbohydrates to sugars, proteins to amino acids, and fats to fatty acids and glycerol.
- 20.3: Overview of Stage II of Catabolism
- This page discusses the significance of Acetyl-CoA in metabolism as an intermediary from the breakdown of carbohydrates, fats, and proteins. It highlights glycolysis as the primary pathway producing Acetyl-CoA aerobically, and explains how fats through beta-oxidation also contribute to its production. Additionally, it mentions the role of Thiolase in cleaving Acetyl-CoA to form Acyl-CoA, enabling entry into the TCA and ETC pathways for energy production.
- 20.4: Stage III of Catabolism
- This page explains the citric acid cycle (Krebs cycle) and the electron transport chain (ETC) within cellular respiration. The citric acid cycle oxidizes acetyl-CoA to produce ATP, NADH, and FADH2, recycling oxaloacetate. The ETC reoxidizes NADH and FADH2, creating a proton gradient necessary for ATP synthesis via ATP synthase. Each NADH can yield approximately 2.5–3 ATP, while FADH2 yields 1.5–2 ATP, highlighting the efficient energy production in mitochondria from organic molecules.
- 20.5: Stage II of Carbohydrate Catabolism
- This page explains glycolysis, a metabolic pathway converting glucose to pyruvate, yielding ATP and NADH. It has two phases: an ATP-consuming phase and an ATP-yielding phase, influenced by oxygen availability. The page also covers diabetes, distinguishing between Type 1 (autoimmune destruction of insulin cells) and Type 2 (insulin resistance), both needing blood sugar monitoring.
- 20.6: Stage II of Lipid Catabolism
- This page details fatty acid oxidation in the mitochondria, where fatty acids are converted into carbon dioxide, water, and energy through a series of reactions starting with the activation to fatty acyl-CoA and followed by β-oxidation. This process yields acetyl-CoA, which can either enter the citric acid cycle or be transformed into ketone bodies.
- 20.7: Stage II of Protein Catabolism
- This page discusses the metabolism of excess amino acids in the liver, highlighting processes like transamination and oxidative deamination. The amino group's final acceptor is α-ketoglutarate, producing glutamate, which is further processed to release ammonium ions. Amino acids are categorized as glucogenic or ketogenic based on their metabolic pathways. Exercise physiologists utilize these metabolic principles to create exercise plans aimed at disease prevention.
- 20.E: Energy Metabolism (Exercises)
- This page explains ATP as the cell's energy currency, detailing its hydrolysis to ADP and the breakdown of macromolecules in the small intestine. It covers glucose metabolism, including glycolysis and β-oxidation, as well as the effects of oxygen on pyruvate. The text also addresses amino acid metabolism, roles of key intermediates like BPG and PEP, NADH reoxidation, ATP yield from specific conversions, and energy dynamics related to various compounds.
- 20.S: Energy Metabolism (Summary)
- This page explains metabolism, which includes catabolism and anabolism. It highlights how carbohydrates, proteins, and lipids are digested and metabolized to produce ATP through glycolysis, the citric acid cycle, and oxidative phosphorylation. ATP yield differs based on oxygen availability, yielding 36-38 ATP with oxygen and 2 without. It also covers fatty acid oxidation via β-oxidation and the catabolism of amino acids for energy, with these processes taking place primarily in mitochondria.