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Showing 91–120 of 1709 reference entries

ChemistryReaction rates and empirical rate laws

Reaction rate measures change over time; a rate law describes its dependence under specified conditions.

MethodChemistryCatalysis and equilibrium

A catalyst changes the reaction pathway and rate, while preserving the equilibrium constant for the same reaction.

ModelBiologyCells as units of life

Cell theory describes the organization and reproduction of cellular life.

ModelBiologyDNA and sequence information

DNA's base sequence stores biological information.

DefinitionBiologyGene expression

Gene expression produces functional RNA or protein from gene information.

DefinitionBiologyDNA replication

Complementary base pairing allows DNA strands to serve as copying templates.

ModelBiologyCell cycle, mitosis and cytokinesis

DNA duplication, nuclear division and cytoplasmic division are distinct events in a typical mitotic cycle.

ModelBiologyMeiosis and chromosome segregation

Typical diploid meiosis halves the number of chromosome sets through two divisions after one DNA replication.

ModelBiologyAlleles and Mendelian segregation

A diploid individual's paired alleles can segregate into gametes.

ModelBiologyBiological evolution

Evolution concerns inherited change across generations.

DefinitionBiologyNatural selection

Heritable variation can change through differences in reproductive contribution.

ModelBiologyGenetic drift

Chance can change allele frequencies independently of an adaptive advantage.

ModelBiologyCommon ancestry and branching lineages

Evolutionary relationships describe descent from shared ancestors.

ModelBiology · ChemistryMetabolism and chemical pathways

Metabolism comprises the regulated chemical reactions of living systems.

DefinitionBiologyOxygenic photosynthesis

Oxygenic photosynthesis couples light-energy capture to carbon fixation and releases oxygen from water.

ModelBiologyAerobic cellular respiration

Aerobic respiration couples nutrient oxidation to ATP production, using oxygen as the final electron acceptor.

ModelBiologyMembranes and transport

Selective membranes and transport proteins regulate movement between a cell and its surroundings.

ModelBiologyEcology and ecosystems

Ecology examines organisms' interactions with one another and their physical environment.

DefinitionBiologyHomeostasis and negative feedback

Feedback can maintain internal variables within functional ranges.

ModelEarth & cosmosRock cycle and geological transformation

Rock materials can change through multiple geological pathways.

ModelEarth & cosmosPlate tectonics

Moving lithospheric plates organize many large-scale geological processes.

ModelEarth & cosmosEarth's water cycle

Water moves among reservoirs above, on and below Earth's surface.

ModelEarth & cosmos · Biology · ChemistryEarth's carbon cycle

Carbon moves through biological, oceanic, atmospheric and geological reservoirs.

ModelEarth & cosmosPlanetary radiative energy balance

Earth's energy storage changes when incoming and outgoing energy differ.

ModelEarth & cosmosAtmospheric greenhouse effect

Infrared absorption and emission affect how Earth loses heat to space.

ModelEarth & cosmosWeather, climate and their time scales

Weather describes short-term conditions; climate describes their longer-term patterns.

DefinitionEarth & cosmosOrbits as gravitational motion

An orbiting body can remain in continuous gravitational free fall.

ModelEarth & cosmosStellar fusion and evolution

Main-sequence stars release energy by fusing hydrogen into helium.

ModelEarth & cosmosHot Big Bang and the cosmic microwave background

Expansion and relic radiation support an earlier hot, dense Universe.

ModelMathematics & logicFirst-order predicates and quantifiers

Quantifiers bind variables over a specified domain.

Definition
DefinitionSource checked

Metabolism and chemical pathways

BiologyChemistry

Metabolism comprises the regulated chemical reactions of living systems.

Key knowledge

Metabolism includes chemical pathways that break down substances and build biological materials. Catabolic pathways break complex molecules into simpler ones, often releasing usable energy; anabolic pathways build complex molecules and require energy input. Enzymes catalyse many of these reactions.

Conditions and scope

  • Individual reactions and pathways differ in their energy changes; not every breakdown step releases usable energy.
  • The entry describes cellular chemistry, not a personal metabolic rate, diet or treatment.
Sources · 3

References

Sources retain their recorded scope. A source link alone does not establish verification of every statement.

  1. What Is Metabolism? (5 June 2024)Abbey Bigler — National Institute of General Medical Sciences (NIGMS), NIHTeaching resourcenigms.nih.govRead source
  2. National Council of Educational Research and Training (NCERT)2 sources
    1. Biology XI: Respiration in PlantsNCERTTextbook chapter · PDFncert.nic.inRead source
    2. Biology XI: BiomoleculesNCERTTextbook chapter · PDFncert.nic.inRead source

Evidence and review

NIGMS's pathway, catabolism/anabolism and enzyme account; no flux or clinical measurement.

2026-10-10 · English pathway and energy distinction checked against the 2024 NIGMS article; medical examples and recommendations are excluded.

Foundational review

2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.

Sources from other places

Agreement within this scope

Breakdown/synthesis pathways and enzyme-mediated cellular reactions.

A pathway can supply both energy and building materials.

  • NCERT2 sources
    • Biology XI: Respiration in Plants
      IndiaEnglish

      §12.2: glycolysis; §12.4.1: tricarboxylic acid cycle; §12.4.2: electron transport and oxidative phosphorylation; §12.6, printed p162: amphibolic pathways

    • Biology XI: Biomolecules
      IndiaEnglish

      §9.1, printed pp105–106: amino acids, fatty acids and glycerides; §9.3–9.6, printed pp108–111: polymers, proteins, carbohydrates and nucleotides; §9.8.2–9.8.4, printed pp114–116: active site, induced fit and conditions; §9.8.5, printed p117: hydrolysis examples

Related reference entries

Explore relationships within this area of study and its connections to other areas.

Showing 1–6 of 6 relationships

Scientific relationships · 6 / 6

The relationship type describes the connection. Its linked statements, sources and conditions define the scope.

  1. Related to
    Relationship sources · 1

    Linked statements

    • Metabolism includes chemical pathways that break down substances and build biological materials. Catabolic pathways break complex molecules into simpler ones, often releasing usable energy; anabolic pathways build complex molecules and require energy input. Enzymes catalyse many of these reactions.
    • Carbon cycles among the atmosphere, organisms, soils, oceans and rocks. Biological processes such as photosynthesis, respiration and decomposition exchange carbon, while weathering, sediment formation and tectonic processes participate in slower geological transfers.

    Photosynthesis, respiration and decomposition transfer carbon through biological processes.

  2. Related to
    Relationship sources · 1

    Linked statements

    • Oxygenic photosynthesis uses captured light energy to support the conversion of carbon dioxide into organic compounds. Water supplies electrons and oxygen is released. This form occurs in photosynthetic plants, algae and cyanobacteria.
    • Metabolism includes chemical pathways that break down substances and build biological materials. Catabolic pathways break complex molecules into simpler ones, often releasing usable energy; anabolic pathways build complex molecules and require energy input. Enzymes catalyse many of these reactions.

    Light-energy capture and carbon fixation supply chemical intermediates and organic compounds in photosynthetic metabolism.

  3. Related to
    Relationship sources · 1

    Linked statements

    • In aerobic glucose breakdown, glycolysis and subsequent oxidation pathways transfer energy and electrons through carriers. Carbon dioxide is released during pyruvate oxidation and the citric acid cycle. The respiratory electron-transport chain ultimately reduces oxygen to water, and a proton gradient supports ATP synthesis.
    • Metabolism includes chemical pathways that break down substances and build biological materials. Catabolic pathways break complex molecules into simpler ones, often releasing usable energy; anabolic pathways build complex molecules and require energy input. Enzymes catalyse many of these reactions.

    Aerobic nutrient breakdown transfers energy through electron transport to ATP production.

  4. Related to
    Relationship sources · 1

    Linked statements

    • Cell membranes are selectively permeable. Passive transport allows net movement down the relevant gradient, through the membrane or transport proteins. Active transport couples movement against a gradient to an energy source, directly or through another gradient. Osmosis is passive net water movement across a selectively permeable membrane.
    • Metabolism includes chemical pathways that break down substances and build biological materials. Catabolic pathways break complex molecules into simpler ones, often releasing usable energy; anabolic pathways build complex molecules and require energy input. Enzymes catalyse many of these reactions.

    Cell metabolism can supply energy for active membrane transport.

  5. Related to
    Relationship sources · 1

    Linked statements

    • Phototrophy and chemotrophy describe energy sources; lithotrophy and organotrophy describe electron donors; autotrophy and heterotrophy describe carbon sources. These classifications can be combined and can vary with conditions. They describe metabolic strategies rather than a single taxonomic division.

    Metabolic strategies specify sources for transformations.

  6. Related to
    Relationship sources · 2

    Linked statements

    • A polymer contains covalently linked subunits derived from monomers. Polysaccharides, polypeptides and nucleic acids use different monomers and linkages; many lipids are not repeating-monomer polymers. Hydrolysis uses water to cleave a susceptible covalent linkage, as in maltose cleavage to two glucose molecules. Condensation can be represented as linkage formation with loss of a small molecule such as water, but cellular polymer synthesis often uses activated precursors rather than direct joining of free monomers with water release.

    Hydrolytic cleavage is one reaction type within metabolism; a bond-cleavage label alone does not determine usable free energy.

Entry detailsPermanent link to this entry ↗
Record identity
bio-metabolism
Revision
core.1
Structured reference record
Essential core · first collection