29.1 An Overview of Metabolism and Biochemical Energy
2 min read•may 7, 2024
ATP powers our cells, acting as a rechargeable battery. It's made of adenosine and three phosphates, with energy-rich bonds between them. When ATP breaks down to , it releases energy for vital cellular functions like muscle movement and nerve signaling.
Our bodies break down food in stages to make ATP. First, in the gut. Then, into the bloodstream. Next, cells further break down nutrients. Finally, use these breakdown products to generate lots of ATP through .
Metabolism and Biochemical Energy
ATP as cellular energy currency
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- primary energy carrier in cells
- Composed of adenosine and three phosphate groups
- High-energy bonds between phosphate groups store energy
- ATP powers cellular processes
- to ADP (adenosine diphosphate) releases energy
- Released energy used for cellular functions (muscle contraction, nerve impulse transmission, biosynthesis)
- to ADP (adenosine diphosphate) releases energy
- regenerate ATP from ADP
- and releases energy
- Released energy phosphorylates ADP back to ATP
Stages of catabolic breakdown
- Stage 1: Digestion
- Food molecules broken down into smaller components
- Occurs in
- hydrolyze into
- Carbohydrates into (glucose, )
- Proteins into (, )
- Lipids into and
- Stage 2: Absorption
- Intestinal cells absorb monomers
- Bloodstream transports monomers to liver
- Stage 3:
- Cells further break down monomers
- breaks down glucose into
- oxidizes pyruvate
- breaks down fatty acids
- Deaminated amino acids enter
- Stage 4: Oxidative phosphorylation
- receives electrons from cellular
- generated across
- uses proton gradient to produce ATP
- Occurs in mitochondria, the powerhouses of the cell
Energetics of catabolism vs anabolism
- Catabolic pathways
- Break down complex molecules into simpler ones
- Release energy as ATP
- release energy
- Glucose, fatty acid, and amino acid oxidation
- Produced ATP powers cellular processes
-
- Synthesize complex molecules from simpler ones
- Require energy input as ATP
- require energy
- Protein, lipid, and polysaccharide synthesis
- ATP consumed to drive reactions forward
- Relationship between catabolic and anabolic pathways
- Catabolic pathways provide ATP for anabolic pathways
- Anabolic pathways use catabolic pathway building blocks and energy to synthesize complex molecules
- Catabolism and balance crucial for
Biochemical Reactions and Energy Transfer
- : The sum of all chemical reactions in an organism
- : Biological catalysts that speed up metabolic reactions
- : Involve electron transfer, crucial for energy production
- : The energy available to do work in a biochemical reaction
- : Non-protein organic molecules that assist enzymes in catalyzing reactions
Key Terms to Review (50)
Absorption: Absorption is the process by which substances are taken up and incorporated into the body. It is a fundamental concept in both spectroscopy and metabolism, as it describes how energy or molecules are captured and utilized by biological systems.
Absorption spectrum: An absorption spectrum is a graph showing the wavelengths of electromagnetic radiation absorbed by a substance, with each peak indicating specific energies at which electrons in the molecules transition to higher energy levels. It is a unique fingerprint for identifying molecular structures in organic chemistry.
Adenosine Diphosphate (ADP): Adenosine diphosphate (ADP) is a nucleotide molecule composed of an adenine base, a ribose sugar, and two phosphate groups. It is a key player in the process of cellular energy production and utilization, serving as an important intermediate in the metabolism of cells.
Adenosine Triphosphate (ATP): Adenosine triphosphate (ATP) is the primary energy currency of living cells. It is a high-energy nucleotide that stores and transports chemical energy within the cell, powering a vast array of cellular processes essential for life.
ADP: ADP, or Adenosine Diphosphate, is a crucial energy-carrying molecule in the body that plays a central role in the processes of metabolism and energy production. It is formed when one of the phosphate groups is removed from the high-energy molecule ATP (Adenosine Triphosphate), and it serves as an important intermediate in various metabolic pathways.
ADP is intimately connected to the topics of 29.1 An Overview of Metabolism and Biochemical Energy, 29.5 Catabolism of Carbohydrates: Glycolysis, and 29.10 Some Conclusions about Biological Chemistry, as it is a key player in the energy currency and transformations that underpin these fundamental biochemical processes.
Alanine: Alanine is a non-essential amino acid that is commonly found in proteins. It plays a crucial role in various biochemical processes, including protein synthesis, energy production, and amino acid metabolism.
Amino Acids: Amino acids are the fundamental building blocks of proteins, which are essential macromolecules that perform a vast array of functions in living organisms. These organic compounds contain an amino group (-NH2), a carboxyl group (-COOH), and a side chain (R-group) that varies among the different types of amino acids. The unique combination and sequence of amino acids give rise to the diverse structures and functions of proteins.
Anabolic Pathways: Anabolic pathways are the metabolic processes that synthesize complex molecules from simpler ones, requiring an input of energy. These pathways are essential for building and repairing tissues, as well as storing energy for future use within the body.
Anabolism: Anabolism is the process within metabolic pathways where complex molecules are synthesized from simpler ones, using energy. It's essential for growth, repair, and differentiation in cells.
ATP (Adenosine Triphosphate): ATP, or adenosine triphosphate, is the primary energy currency of living cells. It is a high-energy nucleotide that stores and transfers the energy needed to power various cellular processes, from muscle contraction to protein synthesis. ATP is central to the understanding of bond dissociation energies, biological substitution reactions, metabolism, and energy production in the body.
ATP Hydrolysis: ATP hydrolysis refers to the chemical reaction in which the high-energy phosphate bond in adenosine triphosphate (ATP) is broken, releasing energy that can be used to drive various cellular processes. This reaction is a fundamental aspect of energy metabolism and is closely connected to the topics of bond dissociation energies and the overview of metabolism and biochemical energy.
ATP Synthase: ATP synthase is a large enzyme complex that plays a crucial role in the production of adenosine triphosphate (ATP), the primary energy currency of cells. This enzyme complex is found in the inner membrane of mitochondria and is responsible for the final step of cellular respiration, coupling the energy released from the electrochemical gradient to the synthesis of ATP.
Beta-Oxidation: Beta-oxidation is the metabolic pathway by which fatty acids are broken down to generate acetyl-CoA, which can then enter the citric acid cycle to produce ATP. It is a crucial process in the catabolism of triacylglycerols and the biosynthesis of fatty acids.
Catabolic Pathways: Catabolic pathways are the metabolic processes that break down complex molecules into simpler ones, releasing energy in the form of ATP. These pathways are essential for providing the energy needed to fuel various cellular functions and maintain homeostasis within the body.
Catabolism: Catabolism is a series of metabolic pathways where complex molecules are broken down into simpler ones, releasing energy stored in chemical bonds. This process is essential for providing the energy necessary for cellular activities and maintenance.
Cellular Catabolism: Cellular catabolism refers to the set of metabolic processes that break down complex molecules within the cells of an organism to release energy. It is a crucial component of the broader concept of metabolism, which encompasses both the breakdown (catabolism) and synthesis (anabolism) of molecules to sustain life.
Cellular Homeostasis: Cellular homeostasis refers to the ability of cells to maintain a stable internal environment, despite changes in external conditions. It is the process by which cells regulate and maintain their optimal physiological state, allowing them to function properly and survive.
Citric acid cycle: The Citric Acid Cycle is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate derived from carbohydrates, fats, and proteins into carbon dioxide. Additionally, it provides precursors for certain amino acids as well as the reducing agent NADH that is used in numerous other biochemical reactions.
Citric Acid Cycle: The citric acid cycle, also known as the tricarboxylic acid (TCA) cycle or the Krebs cycle, is a series of chemical reactions that occur in the mitochondria of cells. It is a key metabolic pathway that generates energy in the form of ATP through the oxidation of acetyl-CoA derived from the breakdown of carbohydrates, fats, and proteins.
Coenzymes: Coenzymes are non-protein organic molecules that assist enzymes in carrying out their catalytic functions within biological reactions. They act as cofactors, helping to facilitate the chemical transformations that are essential for various metabolic processes in living organisms.
Coupled reactions: Coupled reactions in organic chemistry involve two or more reactions occurring simultaneously, where one reaction releases energy and the other uses that energy to proceed. These are pivotal in metabolic pathways for transferring energy from one form to another efficiently.
Deamination: Deamination is the process by which amino groups are removed from organic compounds, typically amino acids, resulting in the conversion of the amino acid into a different molecule. This process is an important part of amino acid metabolism and the breakdown of proteins in the body.
Digestion: Digestion is the complex process of breaking down food into smaller, absorbable nutrients that can be utilized by the body for energy, growth, and maintenance. It is a crucial component of metabolism and plays a vital role in the overall biochemical energy production within the body.
Electron Transport Chain: The electron transport chain is a series of protein complexes and electron carriers located in the inner membrane of mitochondria that are responsible for the final stages of cellular respiration. It is a crucial component of the process that converts the energy stored in organic molecules into the universal energy currency, ATP.
Endergonic Reactions: Endergonic reactions are chemical reactions that require an input of energy to proceed. These reactions are non-spontaneous and cannot occur naturally without the addition of external energy. They are essential components of the metabolic processes that sustain life, as they are responsible for building complex molecules from simpler ones, a process known as anabolism.
Enzymes: Enzymes are biological catalysts that speed up chemical reactions in living organisms without being consumed in the process. They play a crucial role in facilitating various biochemical reactions necessary for life, including those involved in metabolism and DNA replication.
Enzymes: Enzymes are biological catalysts that accelerate chemical reactions in living organisms. They are essential for a wide range of processes, from digestion to energy production, and play a crucial role in maintaining the delicate balance of biochemical reactions that sustain life.
Exergonic Reactions: Exergonic reactions are chemical reactions that release energy, usually in the form of heat, to the surroundings. These types of reactions are spontaneous and occur naturally, as the products of the reaction have less free energy than the reactants, resulting in a net release of energy.
Fatty Acids: Fatty acids are long-chain carboxylic acids that are the primary components of fats and oils. They play a crucial role in various biological processes, including energy storage, cell membrane structure, and signaling pathways, which are relevant to the topics of waxes, fats, and oils, soap, metabolism, and the catabolism of triacylglycerols.
Free Energy: Free energy is a measure of the useful work that can be extracted from a thermodynamic system. It represents the amount of energy available to do work while accounting for the system's entropy and the constraints imposed by the environment. This concept is crucial in understanding chemical reactions, equilibria, and the energy changes associated with various processes in chemistry and biochemistry.
Fructose: Fructose is a monosaccharide, or the simplest form of carbohydrate, that is naturally found in fruits, honey, and some vegetables. It is one of the three dietary sugars, along with glucose and galactose, and is known for its unique properties and role in various metabolic processes.
Gastrointestinal Tract: The gastrointestinal tract, also known as the digestive tract, is a complex system of organs responsible for the ingestion, digestion, and absorption of food to provide the body with the necessary nutrients and energy for various metabolic processes.
Glucose: Glucose is a simple sugar, or monosaccharide, that serves as the primary source of energy for the body's cells. It is a key component in various metabolic processes and plays a central role in carbohydrate chemistry and biochemistry.
Glucose Oxidation: Glucose oxidation is the metabolic process by which glucose, the primary source of energy for cells, is broken down to release chemical energy in the form of ATP. This process is a fundamental part of cellular respiration and is crucial for providing the energy required to sustain various cellular functions.
Glycerol: Glycerol, also known as glycerin, is a simple sugar alcohol that plays a crucial role in various biochemical processes related to fats, oils, and energy metabolism. This three-carbon compound is a key component in the structure of triacylglycerols, the primary storage form of lipids in the body, and is also involved in the production and utilization of energy through its participation in metabolic pathways.
Glycine: Glycine is the smallest and simplest of the 20 standard amino acids that are the building blocks of proteins. It plays a crucial role in various biochemical processes, including protein synthesis, metabolism, and neurotransmission.
Glycolysis: Glycolysis is the metabolic pathway that converts glucose, a six-carbon sugar, into two molecules of pyruvate, a three-carbon compound. This process is the first step in the catabolism of carbohydrates and is a fundamental part of cellular respiration, providing energy in the form of ATP to the cell.
Inner Mitochondrial Membrane: The inner mitochondrial membrane is a highly specialized structure within the mitochondria, the powerhouses of eukaryotic cells. This membrane is responsible for the crucial process of oxidative phosphorylation, which generates the majority of the cell's energy in the form of ATP. The inner mitochondrial membrane is the site where the electron transport chain and ATP synthase are located, enabling the efficient conversion of energy from nutrient molecules into usable chemical energy.
Macromolecules: Macromolecules are large, complex molecules that are essential for the structure and function of living organisms. They are formed through the joining of smaller subunits, known as monomers, and are vital components in the processes of metabolism and biochemical energy production.
Metabolism: Metabolism is the sum of all the chemical reactions that occur within the body to sustain life. It involves the breakdown of molecules to release energy (catabolism) as well as the synthesis of complex molecules from simpler ones (anabolism). Metabolism is a crucial process that powers bodily functions, enables growth and repair, and regulates energy balance.
Mitochondria: Mitochondria are the powerhouses of the cell, responsible for generating the majority of a cell's energy supply through the process of cellular respiration. These organelles play a crucial role in various metabolic pathways, including the biosynthesis of steroids and the citric acid cycle.
Monomers: Monomers are the basic building blocks that make up polymers. They are small, reactive molecules that can be linked together through chemical reactions to form larger, more complex macromolecules known as polymers. Monomers are central to understanding the structure and formation of various types of polymers, including those found in natural and synthetic rubbers, as well as those involved in metabolic processes and chain-growth polymerization.
Monosaccharides: Monosaccharides are the most basic units of carbohydrates, serving as the building blocks for more complex carbohydrate structures. They are simple sugars that cannot be broken down into smaller sugar molecules through hydrolysis.
Nutrient Oxidation: Nutrient oxidation refers to the metabolic process of breaking down nutrients, such as carbohydrates, fats, and proteins, to release the energy stored within their chemical bonds. This process is a fundamental aspect of metabolism and is crucial for providing the body with the energy required to sustain vital functions and support physical activity.
Oxidative Phosphorylation: Oxidative phosphorylation is the metabolic pathway in which cells use enzymes and electron transport chains to convert the energy released by the oxidation of nutrients into adenosine triphosphate (ATP), the primary energy currency of the cell. It is a crucial process that occurs in the mitochondria and is the final stage of cellular respiration.
Polyunsaturated fatty acids: Polyunsaturated fatty acids are a type of fat found in oils from plants and some fish, containing more than one double bond in their hydrocarbon chain. These acids are crucial for human health, influencing inflammation and cell membrane integrity.
Proton Gradient: A proton gradient is a difference in the concentration of hydrogen ions (H+) across a membrane, typically the inner membrane of a mitochondrion or the thylakoid membrane of a chloroplast. This gradient is established and maintained through the transport of protons against their concentration gradient, creating a potential energy source that can be used to drive the synthesis of ATP, the universal energy currency of cells.
Pyruvate: Pyruvate is a key intermediate molecule in cellular metabolism, serving as a central hub that connects various metabolic pathways. It is the final product of glycolysis, the process of breaking down glucose to generate ATP, and plays a crucial role in energy production, biosynthesis, and other essential metabolic processes within the body.
Redox Reactions: Redox reactions, or reduction-oxidation reactions, are a class of chemical reactions where the oxidation state of atoms is changed. They involve the transfer of electrons between chemical species, with one substance losing electrons (being oxidized) and another gaining electrons (being reduced).
α-Amino acids: α-Amino acids are the building blocks of proteins, consisting of a central carbon atom (the α-carbon) to which an amino group, a carboxyl group, a hydrogen atom, and a distinctive side chain (R group) are attached. They play a crucial role in biochemistry as they polymerize to form peptides and proteins.