9: Metabolism
- Page ID
- 187934
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Every living cell must obtain energy and raw materials from its environment in order to survive, grow, and reproduce. The collection of all chemical reactions that occur within a cell is called metabolism (the sum of all chemical reactions that sustain life). In biotechnology, understanding metabolism is essential because nearly every product made by living cells—from antibiotics to biofuels—depends on carefully controlled metabolic reactions. Metabolism allows cells to convert nutrients into usable energy, build complex molecules, and maintain internal balance. Biotechnologist study and manipulate metabolic pathways to increase yields, improve efficiency, and design organisms that perform specific industrial or medical tasks.
Metabolic reactions can be organized into two broad categories:
Catabolism (energy-releasing reactions that break down complex molecules into simpler ones) includes processes such as the breakdown of sugars, fats, and proteins. These reactions release energy that the cell captures and stores for later use.
Anabolism (energy-requiring reactions that build complex molecules from simpler ones) uses that stored energy to synthesize molecules such as proteins, nucleic acids, lipids, and carbohydrates. Together, catabolic and anabolic pathways form an interconnected network that supports all cellular activities.
In biotechnology, both types of pathways are important. Catabolic pathways may be optimized to maximize energy production or waste breakdown, while anabolic pathways are often engineered to increase the production of valuable compounds.
- 9.1: Cellular Energy
- This page outlines the necessity of a constant energy supply for living cells, emphasizing the role of biochemical pathways in managing energy to prevent damage. It explains how cells extract energy through regulated oxidation-reduction reactions to synthesize ATP, the primary energy currency. Specialized molecules, such as electron carriers, facilitate the transport of high-energy electrons, ensuring efficient energy production and metabolic stability to meet cellular demands.
- 9.2: Cellular Respiration
- This page discusses cellular respiration, the process by which cells convert nutrients into ATP energy for various functions such as organization and growth. It occurs in the cytoplasm and mitochondria of eukaryotic cells and in the cytoplasm and cell membrane of prokaryotic cells. The fundamental principles of cellular respiration remain uniform across all living organisms, despite structural differences.
- 9.2.1: Aerobic Respiration
- 9.2.1.1: Glycolysis
- 9.2.1.2: Oxidation of Pyruvate and the Citric Acid Cycle
- 9.2.1.3: Electron Transport Chain
- 9.2.1.4: Oxidative Phosphorylation
- 9.2.1.5: Aerobic Respiration in Eukaryotes and Prokaryotes- Similarities and Differences
- 9.2.2: Protein Catabolism
- 9.2.3: Lipid Catabolism
- 9.3: Anaerobic Respiration
- This page discusses anaerobic respiration, a type of cellular respiration occurring without oxygen. It details the use of alternative electron acceptors, such as nitrate and sulfate, leading to ATP production, albeit less efficiently than aerobic respiration. The page emphasizes the role of anaerobic respiration in prokaryotes, ecological processes like nutrient cycling, and the selection of specific electron acceptors based on environmental conditions.
- 9.4: Fermentation
- This page discusses fermentation as an anaerobic process crucial for ATP production without oxygen, relying on glycolysis to convert glucose to pyruvate while regenerating NAD⁺. The main purpose is to sustain NAD⁺ levels to continue glycolysis, as ATP production halts without it. While fermentation provides less ATP compared to aerobic respiration, it is vital for cellular survival in low or no oxygen environments.