Biology Vocabulary

Abiotic Factor

• A non-living component of an ecosystem, such as temperature, light, water, or minerals.

Absorption Spectrum

• The range of light wavelengths a pigment is capable of absorbing.

Accessory Pigment

• A pigment that absorbs light energy and transfers it to chlorophyll a.

Activation Energy

• The energy required to start a chemical reaction. Enzymes lower this energy barrier.

Active Site

• The specific region of an enzyme where the substrate binds and catalysis occurs.

Allele

• A variant form of a gene.

Allosteric Regulation

• The regulation of an enzyme by binding an effector molecule at a site other than the active site, altering the enzyme's shape and activity.

Amphipathic

• A molecule containing both hydrophobic and hydrophilic regions (e.g., phospholipids).

Anabolism

• The synthesis of complex molecules from simpler ones; a process that consumes energy.

Anaerobic Metabolism

• Metabolic processes that occur without oxygen.

Analogous Structure

• Structures in different species that have similar functions but have evolved separately, thus do not share a common ancestor.

Anticodon

• A sequence of three nucleotides in tRNA that is complementary to a codon in mRNA.

Apoptosis

• Programmed cell death.

Aquaporin

• A channel protein in a cell membrane that facilitates the diffusion of water.

Autosome

• Any chromosome that is not a sex chromosome.

Biodiversity

• The variety of life in the world or in a particular habitat or ecosystem.

Biogeography

• The study of the geographic distribution of species.

Biome

• A large naturally occurring community of flora and fauna occupying a major habitat, e.g., forest or tundra.

Biotic Factor

• A living component of an ecosystem (e.g., plants, animals, bacteria).

Carbon Cycle

• The biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.

Carrying Capacity

• The maximum population size that an environment can sustain given available resources, symbolized as K.

Catabolism

• The breakdown of complex molecules into simpler ones; a process that releases energy.

Catalyst

• A substance that speeds up a reaction without being consumed in the process.

Cell Cycle

• The series of events that take place in a cell leading to its division and duplication.

Cellular Differentiation

• The process by which a cell becomes specialized in structure and function.

Chemiosmosis

• The movement of ions across a selectively permeable membrane, down their electrochemical gradient.

Chemoautotroph

• An organism that obtains energy from chemical reactions and synthesizes its own organic compounds from inorganic substances.

Cline

• A gradual change in a character or feature across a geographical area, usually correlated with an environmental transition.

Codominance

• A condition in which both alleles for a gene are fully expressed.

Codon

• A sequence of three nucleotides in DNA or RNA that codes for a specific amino acid or signals the termination of translation.

Coenzyme

• An organic molecule that is required for the function of certain enzymes (e.g., vitamins).

Coevolution

• The process by which two species evolve in response to each other.

Cofactor

• A non-protein chemical compound that is required for an enzyme's activity.

Compartmentalization

• The presence of membrane-bound organelles in eukaryotic cells, allowing for specialized functions to occur in specific regions.

Convergent Evolution

• The independent evolution of similar features in different lineages.

Cyclic AMP (cAMP)

• A secondary messenger molecule involved in signal transduction pathways.

Denaturation

• The process in which proteins or nucleic acids lose their structure due to external stress or compounds, such as by application of heat, strong acid or base or a disruptive solvent, that removes the native state.

Density-Dependent Factor

• A factor that limits population growth and has a greater effect as population density increases.

Detritivore

• An organism that feeds on dead organic material (detritus).

DNA Ligase

• An enzyme that joins DNA fragments together by catalyzing the formation of a phosphodiester bond.

Ecological Niche

• The role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces.

Ecological Pyramid

• A graphical representation of the energy or biomass contained at each trophic level in an ecosystem.

Ecological Succession

• The process of change in the species structure of an ecological community over time.

Ecosystem

• A community of interacting organisms and their physical environment.

Ecosystem Stability

• The ability of an ecosystem to maintain its structure and function over time in the face of external stress.

Endergonic Reaction

• A reaction that requires energy input to proceed (
  ΔG > 0
  ).

Endosymbiosis

• A symbiotic relationship in which one organism lives inside the other.

Entropy

• A measure of disorder or randomness in a system.

Evo-Devo

• Evolutionary developmental biology; a field of biological research that compares the developmental processes of different organisms to infer the ancestral relationships between them and how developmental processes evolved.

Exergonic Reaction

• A reaction that releases energy (
  ΔG < 0
  ).

Exponential Growth

• Population growth under ideal conditions, resulting in a population increase at a constant rate.

Food Chain

• A linear sequence of organisms through which nutrients and energy pass as one organism eats another.

Food Web

• A network of interconnected food chains in an ecosystem.

Gamete

• A haploid reproductive cell (sperm or egg).

Gel Electrophoresis

• A laboratory method used to separate mixtures of DNA, RNA, or proteins according to their size and charge.

Gene Expression

• The process by which information from a gene is used in the synthesis of a functional gene product (protein or RNA).

Gene Flow

• The transfer of genetic variation from one population to another.

Gene Pool

• The total collection of genes in a population at any one time.

Genetic Bottleneck

• A sharp reduction in the size of a population due to environmental events or human activities which reduces the genetic diversity in the population.

Genetic Code

• The set of rules by which information encoded in genetic material (DNA or RNA) is translated into proteins by living cells.

Genetic Drift

• A change in the allele frequency of a population as a result of chance events rather than natural selection.

Genetic Engineering

• The direct manipulation of an organism's genes using biotechnology.

Genetic Equilibrium

• A state in which the allele frequencies in a population are not changing over time.

Genetic Transplantation

• The process of replacing genes in a cell with genes from another cell.

Genomic Imprinting

• The epigenetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner.

Glycolipid

• A lipid with a carbohydrate attached.

Glycoprotein

• A protein with a carbohydrate attached.

Greenhouse Gas

• A gas that absorbs and emits radiant energy within the thermal infrared range.

Greenhouse Effect

• The process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without its atmosphere.

Gross Primary Productivity (GPP)

• The total rate of photosynthesis in an ecosystem.

Habitat

• The natural home or environment of an animal, plant, or other organism.

Haploid

• Having a single set of unpaired chromosomes (n).

Homeotic Genes

• Genes that regulate the development of anatomical structures in various organisms.

Homologous Chromosomes

• Chromosomes with the same gene sequence, one inherited from each parent.

Homologous Structures

• Structures in different species that are similar because of common ancestry.

Hox Genes

• A subset of homeotic genes that are involved in specifying the identity of body segments during embryonic development.

Hybrid

• The offspring resulting from cross-breeding between two different species or varieties.

Hypertonic

• Having a higher solute concentration compared to another solution.

Hypotonic

• Having a lower solute concentration compared to another solution.

Incomplete Dominance

• A condition in which neither allele is fully dominant, resulting in a phenotype that is intermediate between the two homozygous phenotypes.

Independent Assortment

• The random segregation of genes during meiosis.

Independent Variable

• The variable that is manipulated or changed in an experiment.

Inducible Gene

• A gene that is expressed only in the presence of an inducer.

Interspecific Competition

• Competition between individuals of different species for the same resources.

Intraspecific Competition

• Competition between individuals of the same species for the same resources.

Introduced Species

• A species that is not native to a specific location.

Introns

• Non-coding sections of a gene that are transcribed into pre-mRNA but are removed during RNA splicing.

Isotonic

• Having the same solute concentration as another solution.

K-Selection

• Selection for life history traits that are advantageous at high population densities.

Keystone Species

• A species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically.

Ligand

• A molecule that binds to a receptor protein.

Limiting Factors

• Environmental conditions that limit the growth, abundance, or distribution of an organism or a population of organisms in an ecosystem.

Logistic Growth

• Population growth that levels off as population size approaches carrying capacity.

Macromolecule

• A very large molecule, such as a polymer, composed of many smaller subunits (monomers).

Metabolic Pathway

• A series of chemical reactions that occur in a cell.

Monohybrid Cross

• A cross between two individuals that are heterozygous for one gene.

Morphogenesis

• The biological process that causes an organism to develop its shape.

Multiple Alleles

• More than two alleles exist for a particular gene in a population.

Mutation

• A change in the DNA sequence of a gene.

Mutualism

• A symbiotic relationship in which both species benefit.

NAD+

• Nicotinamide adenine dinucleotide, a coenzyme used in redox reactions.

NADP+

• Nicotinamide adenine dinucleotide phosphate, a coenzyme used in anabolic reactions, such as photosynthesis.

Negative Control

• A regulatory mechanism that inhibits gene expression.

Net Primary Productivity (NPP)

• The rate at which energy is stored as biomass by plants or other primary producers and made available to the consumers in the ecosystem.

Nitrogen Cycle

• The biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystems.

Non-Nuclear Inheritance

• The transmission of genes that are not located in the cell nucleus.

Nuclear Division

• The division of the nucleus of a cell during mitosis or meiosis.

Nutrient Cycle

• The movement and exchange of organic and inorganic matter back into the production of living matter.

Okazaki Fragments

• Short sequences of DNA nucleotides which are synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand during DNA replication.

P53 Gene

• A tumor suppressor gene that regulates cell cycle and apoptosis.

Peptide Bond

• A chemical bond formed between two amino acids.

Phagocytosis

• A process by which a cell engulfs a solid particle.

Phenotype

• The observable characteristics of an individual resulting from the interaction of its genotype with the environment.

Phospholipid

• A lipid containing a phosphate group, making it amphipathic.

Phosphorylation Cascade

• A sequence of signaling pathway events where one enzyme phosphorylates another, causing a chain reaction that amplifies the initial signal, leading to altered cell function.

Photoautotroph

• An organism that uses light energy to synthesize organic compounds from carbon dioxide and water.

Photolysis

• The decomposition or separation of molecules by the action of light.

Phylogeny

• The evolutionary history of a species or group of species.

Pinocytosis

• A process by which a cell engulfs extracellular fluid.

Plasmolysis

• The contraction of the protoplast of a plant cell as a result of loss of water from the cell.

Polar Molecule

• A molecule with an uneven distribution of charge, resulting in a dipole moment.

Polygenic Inheritance

• The determination of a trait by more than one gene.

Polymerase Chain Reaction (PCR)

• A laboratory technique used to amplify specific DNA sequences.

Polymorphism

• The presence of different forms or types of individuals in a population.

Polyploidy

• A condition in which an organism has more than two complete sets of chromosomes.

Positive Control

• Regulatory mechanism that initiates gene expression.

Positive Feedback

• A control mechanism in which the end product of a process stimulates the process.

Primary Consumer

• An organism that feeds on primary producers (e.g., herbivores).

Protein Kinase

• An enzyme that adds phosphate groups to proteins.

Quorum Sensing

• The regulation of gene expression in response to fluctuations in cell-population density.

R-Selection

• Selection for life history traits that are advantageous at low population densities.

Receptor

• A protein that binds to a specific ligand, triggering a cellular response.

Repressor

• A protein that binds to DNA and inhibits gene expression.

Restriction Enzyme

• An enzyme that cuts DNA at specific sequences.

Reverse Transcriptase

• An enzyme that synthesizes DNA from an RNA template.

RNA (all three kinds)

• Ribonucleic acid, including mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA), each with distinct roles in gene expression.

Secondary Messenger

• A molecule that relays signals received at receptors on the cell surface to target molecules in the cytosol or nucleus.

Segregation

• The separation of alleles during gamete formation.

Selectively Permeable

• A membrane that allows some substances to cross more easily than others.

Sex-Linked Gene

• A gene located on a sex chromosome.

Speciation

• The process by which new species arise.

Stromatolite

• A layered sedimentary structure formed by the growth of microbial mats.

Survivorship Curve

• A graph showing the number or proportion of individuals surviving at each age for a given species or group.

Synapsis

• The pairing of homologous chromosomes during meiosis.

Template Strand

• The DNA strand that is used as a template for RNA synthesis.

Test Cross

• A cross between an individual with an unknown genotype and a homozygous recessive individual.

Transgenic Organism

• An organism that contains genetic material into which DNA from an unrelated organism has been artificially introduced.

Trophic Level

• The position an organism occupies in a food chain.

Turgor Pressure

• The pressure exerted by water inside a plant cell against the cell wall.