Metabolic reactions are the foundation of life, transforming nutrients into energy and building blocks. These processes involve breaking down complex molecules and building new ones, all powered by ATP, the cellular energy currency.
Cellular metabolism is a delicate balance of - reactions and hormonal regulation. These processes work together to maintain energy levels, build essential molecules, and keep the body functioning smoothly in various conditions.
Metabolic Reactions
Breakdown of polymers to monomers
Top images from around the web for Breakdown of polymers to monomers
Overview of Metabolic Reactions | Anatomy and Physiology II View original
Catabolic reactions break down complex molecules into simpler ones through a process called
Polymers such as polysaccharides (starch, glycogen), proteins, and triglycerides are broken down into their respective monomers (glucose, amino acids, fatty acids, and glycerol)
Hydrolysis reactions use water molecules to cleave the chemical bonds between monomers, a process catalyzed by specific to increase reaction rates
Monomers released from catabolic reactions serve as energy sources or building blocks for
Glucose from polysaccharide breakdown enters or the for ATP production
Amino acids from protein breakdown can be used to synthesize new proteins or converted to glucose or fatty acids
Fatty acids from triglyceride breakdown undergo to generate for the
Formation of polymers from monomers
Anabolic reactions construct complex molecules from simpler ones through
Monomers such as monosaccharides (glucose), amino acids, fatty acids, and glycerol are combined to form their respective polymers (polysaccharides, proteins, triglycerides)
Dehydration synthesis removes water molecules to create covalent bonds between monomers, a process catalyzed by specific enzymes to increase reaction rates
Anabolic reactions require an input of energy, typically in the form of ATP, to drive the formation of new chemical bonds
Glucose monomers are combined to form storage polysaccharides like starch in plants and glycogen in animals
Amino acids are linked together to form polypeptide chains, which fold into functional proteins
Fatty acids and glycerol are combined to form triglycerides for energy storage in adipose tissue
ATP as metabolic energy currency
serves as the primary energy currency in living organisms
ATP consists of an adenosine molecule bonded to three phosphate groups
Energy is released when the terminal phosphate group is hydrolyzed, converting ATP to (adenosine diphosphate) and inorganic phosphate (Pi)
ATP+H2O→ADP+Pi+Energy
The energy released from ATP hydrolysis drives endergonic reactions that require an energy input
Anabolic reactions like protein synthesis and glycogen synthesis utilize ATP to form new chemical bonds
Active transport mechanisms use ATP to move molecules against their concentration gradients across membranes
ATP is regenerated from ADP and Pi through or oxidative phosphorylation
ADP+Pi+Energy→ATP
Substrate-level phosphorylation occurs during and the citric acid cycle
Oxidative phosphorylation takes place in the of mitochondria
Cellular Metabolism
Oxidation-reduction in cellular metabolism
Oxidation-reduction (redox) reactions involve the transfer of electrons between molecules
Oxidation is the loss of electrons, while reduction is the gain of electrons
Electron carriers like (nicotinamide adenine dinucleotide) and (flavin adenine dinucleotide) play crucial roles in cellular metabolism
NAD+ is reduced to , while FAD is reduced to upon accepting electrons
Redox reactions are essential in catabolic pathways that break down nutrients to generate ATP
Glycolysis, the citric acid cycle, and the electron transport chain all involve redox reactions
Electrons from NADH and FADH2 are used to create a proton gradient that drives ATP synthesis through oxidative phosphorylation
Redox reactions also participate in anabolic pathways that synthesize complex molecules
Fatty acid synthesis and amino acid synthesis require reducing power in the form of (reduced nicotinamide adenine dinucleotide phosphate)
Hormones in metabolic regulation
, secreted by pancreatic beta cells, is a key anabolic hormone
Stimulates glucose uptake by muscle and adipose tissue, promoting glycogen synthesis and
Enhances protein synthesis and inhibits protein breakdown in muscle tissue
, secreted by pancreatic alpha cells, is a major catabolic hormone
Stimulates (glycogen breakdown) and (glucose synthesis from non-carbohydrate precursors) in the liver, increasing blood glucose levels
Promotes (triglyceride breakdown) in adipose tissue, releasing fatty acids into the bloodstream
Cortisol, secreted by the adrenal cortex, is a catabolic hormone involved in the stress response
Stimulates (protein breakdown) in muscle tissue, providing amino acids for
Enhances in adipose tissue and gluconeogenesis in the liver, ensuring adequate glucose supply during stress
, secreted by the anterior pituitary gland, has anabolic effects
Stimulates protein synthesis and muscle growth, promoting positive nitrogen balance
Induces lipolysis in adipose tissue, mobilizing fatty acids for energy production
Antagonizes insulin action, reducing glucose uptake and utilization by tissues
Metabolic Regulation and Control
are interconnected series of chemical reactions that occur in cells to maintain homeostasis
Enzymes are protein catalysts that significantly increase the rate of metabolic reactions
are non-protein organic molecules that assist enzymes in catalyzing reactions
is a regulatory mechanism where the end product of a metabolic pathway inhibits an earlier step in the pathway
involves the binding of molecules to sites on enzymes other than the active site, altering enzyme activity