Chapter 15
Metabolism is composed of many interconnected reactions
ATP –universal free energy currency
Oxidation of carbon fuels is an important source of energy
Metabolic pathway contain many recurring motifs
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Guidelines and tips
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Understanding Metabolism: The Role of ATP, Energy Extraction, and Metabolic Pathways, Study Guides, Projects, Research of Design
An overview of metabolism, the role of ATP as the universal energy currency, and the principles governing energy manipulations in all cells. It covers the importance of metabolic pathways, energy extraction and use, and the distinction between anabolic and catabolic pathways. The document also discusses the role of enzymes, energy reserves, and the regulation of metabolism.
Typology: Study Guides, Projects, Research
2021/2022
1 / 54
This page cannot be seen from the preview
Don't miss anything!
Related documents
Partial preview of the text
Download Understanding Metabolism: The Role of ATP, Energy Extraction, and Metabolic Pathways and more Study Guides, Projects, Research Design in PDF only on Docsity!
Chapter 15
Metabolism is composed of many interconnected reactions ATP – universal free energy currency Oxidation of carbon fuels is an important source of energy Metabolic pathway contain many recurring motifs
Cells extract energy from their environment and use the energy for a host of biological activities including biosynthesis. The reactions of energy extraction and energy use are called metabolism or intermediary metabolism. Basic principles govern energy manipulations in all cells:
- Molecules are degraded or synthesized stepwise in a series of reactions termed metabolic pathways.
- ATP is the energy currency of life.
- ATP can be formed by the oxidation of carbon fuels.
- Although many reactions occur inside a cell, there are a limited number of reaction types involving particular intermediates that are common to all metabolic pathways.
- Metabolic pathways are highly regulated.
Metabolic pathways can be divided into two types:
- Catabolic pathways combust carbon fuels to synthesize ATP.
- Anabolic pathways use ATP and reducing power to synthesize large biomolecules. Some pathways, called amphibolic pathways, can function anabolically or catabolically. Although anabolic and catabolic pathways may have reactions in common, the regulated, irreversible reactions are always distinct.
In order to construct a metabolic pathway, two criteria must be met:
- The individual reactions must be specific.
- The pathway in total must be thermodynamically favorable. A thermodynamically unfavorable reaction in a pathway can be made to occur by coupling it to a more favorable reaction.
Energy derived from fuels or light is converted into adenosine triphosphate (ATP), the cellular energy currency. The hydrolysis of ATP is exergonic because the triphosphate unit contains two phosphoanhydride bonds that are unstable. The energy released on ATP hydrolysis is used to power a host of cellular functions.
Consider the following endergonic reaction: Coupling this reaction with ATP hydrolysis renders the formation of B exergonic.
ATP has a high phosphoryl-transfer potential because of four key factors:
- Resonance stabilization of ADP and Pi
- Electrostatic repulsion.
- Increase in entropy.
- Stabilization by hydration.
ATP has a phosphoryl-transfer potential intermediate between high phosphoryl- potential compounds derived from fuel molecules and acceptor molecules that require the addition of a phosphoryl group for cellular needs. Creatine phosphate serves as an energy reserve in vertebrate muscle.
Oxidation reactions involve loss of electrons. Such reactions must be coupled with reactions that gain electrons. The paired reactions are called oxidation-reduction reactions or redox reactions. The carbon atoms in fuels are oxidized to yield CO 2 , and the electrons are ultimately accepted by oxygen to form H 2 O. The more reduced a carbon atom is, the more free energy is released upon oxidation. Fats are a more efficient food source than glucose because fats are more reduced.