Glossary
- Page ID
- 135985
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\dsum}{\displaystyle\sum\limits} \)
\( \newcommand{\dint}{\displaystyle\int\limits} \)
\( \newcommand{\dlim}{\displaystyle\lim\limits} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)| Words (or words that have the same definition) | The definition is case sensitive | (Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages] | (Optional) Caption for Image | (Optional) External or Internal Link | (Optional) Source for Definition |
|---|---|---|---|---|---|
| (Eg. "Genetic, Hereditary, DNA ...") | (Eg. "Relating to genes or heredity") |  |
The infamous double helix | https://bio.libretexts.org/ | CC-BY-SA; Delmar Larsen |
|
Word(s) |
Definition |
Image | Caption | Link | Source |
|---|---|---|---|---|---|
| Allelopathy | The production of chemicals by an organism that inhibit the growth or survival of other nearby organisms | ||||
| Trophic cascade | An ecological process where changes in the population of top predators cause a chain reaction affecting multiple lower levels in the food web, altering the abundance or behavior of species across the ecosystem | ||||
| Bioaccumulation | The build-up of substances, such as toxins, in an organism over time | ||||
| Endophyte | An organism, often a protist or fungus, that lives inside plants without causing harm | ||||
| Bioluminescence | The production and emission of light by living organisms (e.g. fireflies, dinoflagellates, etc.) | ||||
| Sessile | An organism that is fixed in one place and does not move | ||||
| Eutrophication | The process where water bodies receive excess nutrients, leading to dense plant and algal growth and oxygen depletion | ||||
| Bioindicator | An organism used to monitor the health of an environment or ecosystem | ||||
| Trophic level | The position an organism occupies in a food chain or food web | ||||
| primary producer | An organism that produces organic compounds from inorganic material (e.g., CO₂) via photosynthesis or other means, and thus forms the base of a food web | ||||
| Eyespot | A light-sensitive organelle that helps the organism detect light | ||||
| Phycoerythrin | A red pigment found in red algae and some other photosynthetic organisms that aids in capturing light for photosynthesis | ||||
| Carotenoid | Pigments found in plants, algae, and some bacteria that help capture light energy and protect cells from damage | ||||
| Plankton | Small organisms that drift or float in aquatic environments, including microscopic plants (phytoplankton) and animals (zooplankton) | ||||
| Spore | A reproductive cell capable of developing into a new organism without fusion with another cell, often resistant to harsh conditions | ||||
| Cytoplasmic streaming | The directed flow of cytoplasm within a cell that helps distribute nutrients, organelles, and other materials | ||||
| Spirochetes | A group of spiral-shaped bacteria characterized by their unique corkscrew movement | ||||
| Morphology | The study of the form, structure, and shape of organisms or their specific parts | ||||
| Amoebozoa | A lineage of protists that typically move and feed by broad, lobe‑shaped pseudopodia rather than flagella | ||||
| Chromalveolata (or SAR) | A large grouping (sometimes treated as the SAR clade: Stramenopiles + Alveolata + Rhizaria) of protists derived from secondary endosymbiosis of a red alga, including many photosynthetic and heterotrophic forms | ||||
| Supergroup | A large, broad classification category used to group major lineages of eukaryotes, including diverse protist groups, based on common ancestry and genetic relationships | ||||
| Euglenozoa | A group within Excavata that includes flagellated protists; some are autotrophic, heterotrophic or mixotrophic | ||||
| Brown algae | Large, multicellular protists (seaweeds) belonging to the stramenopiles; often found in colder marine environments | ||||
| Red algae (Rhodophyta) | Mostly multicellular, photosynthetic protists that contain phycoerythrin (a red pigment) and lack flagella in most cases | ||||
| Green algae (Chlorophyta) | A group of photosynthetic protists with chlorophylls a and b, cellulose cell walls, and close evolutionary relationship to land plants | ||||
| Radiolaria | Marine protists with intricate silica skeletons and fine pseudopodia radiating outwards; their skeletal remains accumulate in deep‑sea sediments | ||||
| Foraminifera (forams) | Unicellular, mostly marine protists with porous shells (tests), pseudopodia that extend through the pores, and often important in the fossil record | ||||
| Stramenopiles (Heterokonta) | A subgroup of protists (within SAR) that often have two unequal flagella (one “hairy”) and include diatoms, brown algae and water molds | ||||
| Alveolata | A subgroup of protists (within the SAR/Chromalveolata) characterized by membrane‑bound sacs (alveoli) just under the cell membrane | ||||
| Excavata | A major eukaryotic supergroup of protists characterized by a feeding groove “excavated” from one side, often with flagella and diverse nutrition modes | ||||
| Archaeplastida | A supergroup of eukaryotes (including protists) derived via primary endosymbiosis of a cyanobacterium, containing green algae, red algae and their relatives | ||||
| Rhizaria | A supergroup of mostly amoeboid protists with hairy pseudopodia (filose or reticulose), often with mineralized tests (shells) | ||||
| Exocytosis | A cellular process where materials contained in vesicles are transported to and released outside the cell by fusion of the vesicle membrane with the plasma membrane | ||||
| Cilia | Short, hair-like structures on the surface of some cells that move in coordinated waves to help with locomotion or to move fluids and particles across the cell surface | ||||
| Phagocytosis | The process by which a cell engulfs large particles or other cells, important in early eukaryotes for acquiring endosymbionts | ||||
| Pellicle | A flexible protein layer beneath the cell membrane that supports and protects some protists | ||||
| Colonial | A group of cells/individuals living together but capable of independent survival | ||||
| Mixotroph | An organism that can obtain energy and carbon both through photosynthesis and by consuming organic material | ||||
| Pseudopodia | Temporary, foot-like extensions of the cytoplasm used by some protists for movement and capturing food | ||||
| Protist | A diverse group of mostly unicellular eukaryotes that are not plants, animals, or fungi. Not monophyletic. | ||||
| primary endosymbiosis | The event where a eukaryotic host cell engulfed a prokaryote (e.g., a cyanobacterium) which then became a plastid (chloroplast) in photosynthetic eukaryotes | ||||
| secondary endosymbiosis | A subsequent event in which a eukaryotic cell (already containing a plastid) is engulfed by another eukaryote, passing the plastid into a new lineage | ||||
| cytoskeleton | A network of protein filaments (microtubules, actin filaments) in eukaryotic cells that allows for support, movement, and transport of organelles. | ||||
| mitochondrion | The organelle in eukaryotic cells responsible for aerobic (oxygen‑based) cellular respiration; evidence shows it evolved from an aerobic prokaryote (plural: mitochondria) | ||||
| eukaryote | A type of cell (or organism composed of such cells) that has a defined nucleus and organelles enclosed by membranes; emerged from prokaryotic ancestors through several evolutionary steps | ||||
| MRSA | Methicillin-Resistant Staphylococcus aureus; a strain of the bacterium Staphylococcus aureus that has developed resistance to many common antibiotics, making infections difficult to treat | ||||
| Evolution | The process through which populations of organisms change over generations due to alterations in genetic composition | ||||
| Natural Selection | A mechanism of evolution where individuals with traits that enhance survival and reproduction are more likely to pass on their traits to the next generation. It is sometimes called "survival of the fittest" | ||||
| Descent with Modification | Darwin's concept that all life is related to one another, and that species evolve over time, with changes accumulating across generations, leading to a divergence from common ancestors | ||||
| Adaptive Evolution | Evolution that results in organisms being better suited to their environment due to the advantageous traits passed on through natural selection | ||||
| Variation | The differences in traits among individuals within a population. These variations can be inherited and play a crucial role in natural selection | ||||
| Adaptation | A trait that has evolved through natural selection, providing a functional advantage in a particular environment | ||||
| Selective Pressure | External factors that influence which traits are advantageous and therefore passed on, such as predation, food availability, or climate | ||||
| Species | A group of individuals that can interbreed and produce fertile offspring (based on the Biological Species Concept). Over time, species can diverge due to evolutionary processes | ||||
| Biological Species Concept | A definition of species as a group of individuals that interbreed and produce fertile, viable offspring. It distinguishes species based on their ability to reproduce successfully. | ||||
| Gene Pool | The complete set of genetic information, including all the gene variants, in a population or species. | ||||
| Asexual Reproduction | A mode of reproduction where offspring arise from a single organism, inheriting the genes of that parent only. | ||||
| Sexual Reproduction | The process where two organisms contribute genetic information (through gametes like sperm and egg) to produce offspring, allowing for genetic diversity. | ||||
| Hybrid | An organism resulting from the mating of two different species, typically infertile due to genetic incompatibility. | ||||
| Morphological Species Concept | A species concept that defines species based on their physical characteristics (morphology). | ||||
| Allopatric Speciation | The process of speciation that occurs when a population becomes geographically isolated and evolves into a new species. | ||||
| Sympatric Speciation | Speciation that occurs without geographic isolation, often due to genetic or behavioral factors that lead to reproductive isolation. | ||||
| Adaptive Radiation | The diversification of a group of organisms into different species, each adapted to a specific environment or niche. | ||||
| Polyploidy | A condition in which an organism has extra sets of chromosomes, which can lead to speciation, especially in plants. | ||||
| Autopolyploidy | A form of polyploidy where an individual has multiple sets of chromosomes from the same species. | ||||
| Allopolyploidy | A form of polyploidy that occurs when two different species interbreed and produce viable, fertile offspring with extra sets of chromosomes. | ||||
| Reproductive Isolation | A state where different species or populations are unable to interbreed successfully, leading to speciation. | ||||
| Prezygotic Barrier | A mechanism that prevents fertilization from occurring, thus preventing species from reproducing. | ||||
| Postzygotic Barrier | A reproductive barrier that occurs after fertilization, preventing the offspring from developing into fertile, viable adults. | ||||
| Temporal Isolation | A type of prezygotic barrier where species reproduce at different times, preventing interbreeding. | ||||
| Habitat Isolation | A form of reproductive isolation where species occupy different habitats, reducing the likelihood of mating. | ||||
| Dispersal | The movement of individuals of a species to new geographic areas, which can lead to allopatric speciation. | ||||
| Vicariance | The physical splitting of a habitat, leading to geographical isolation and allopatric speciation. | ||||
| Founder Species | The original species from which other species evolve in adaptive radiation. | ||||
| Convergent Evolution | A process where unrelated species evolve similar traits due to similar environmental pressures. | ||||
| Phylogeny | A diagram showing evolutionary relationships among species, often resembling a branching tree. | ||||
| Allele Frequency | The relative frequency of an allele (gene variant) in a population. | ||||
| Extinction | The process by which a species, genus, or family ceases to exist. | ||||
| Mass Extinction | A rapid event leading to the loss of a large number of species across multiple environments. | ||||
| Background Extinction Rate | The normal rate at which species go extinct due to natural causes. | ||||
| Anthropogenic | Refers to human-induced changes or impacts on the environment. | ||||
| Biodiversity | The variety of life forms in an ecosystem, including species diversity. | ||||
| Ecology | Study of interactions between organisms and their environment | ||||
| Niche | All the biotic and abiotic factors required for the survival and persistence of a species; the role and position a species has in its environment | ||||
| Predation | Interaction where one organism consumes another | ||||
| Symbiosis | Close and long-term biological interaction between two species | ||||
| Aposematic | Organism that expresses warning signals (e.g. coloration) to indicate toxicity or danger | ||||
| Mutualism | Interaction in which both species benefit | ||||
| Taxonomy | The science of classifying organisms based on shared characteristics | ||||
| Binomial Nomenclature | The two-part scientific naming system for organisms, consisting of the genus and species name | ||||
| Homologous Structures | Anatomical features that are similar in different species due to shared ancestry | ||||
| Analogous Structures | Features that serve similar functions in different species but do not share a common ancestry | ||||
| Clade | A group of organisms that includes a common ancestor and all its descendants | ||||
| Molecular Systematics | The use of molecular data to determine evolutionary relationships | ||||
| Monophyletic Group | A group consisting of a common ancestor and all its descendants | ||||
| Parsimony | The principle that the simplest explanation, requiring the fewest evolutionary changes, is preferred | ||||
| Outgroup | A species or group that is closely related to but not part of the group being studied, used to infer the root of a phylogenetic tree | ||||
| Derived Character | A trait that appears in a recent ancestor and is unique to a particular clade | ||||
| Horizontal Gene Transfer | Movement of genetic material between organisms other than by the transmission of DNA from parent to offspring | ||||
| Apomorphy | A derived or new trait that evolved in a particular lineage and is not present in the lineage's ancestral form; distinguishes members of a clade from their common ancestors and is a key characteristic used in phylogenetic analysis to define evolutionary relationships between species | ||||
| Sister Taxa | Two descendants that split from the same node in a phylogenetic tree | ||||
| Polyphyletic Group | A group of organisms that does not include the most recent common ancestor; a group of organisms that does not share an ancestor exclusive only to that group | ||||
| Maximum Likelihood | A statistical method used to estimate the probability of a particular phylogenetic tree being correct | ||||
| Plesiomorphy | An ancestral trait that is inherited from a distant common ancestor and is shared by multiple species or groups; often present in both the ancestral and descendant groups, making them less useful for distinguishing relationships in a specific clade | ||||
| Anagenesis | Evolutionary change within a single lineage without branching | ||||
| Cladogenesis | The process by which a species splits into two or more distinct species | ||||
| Polytomy | A section of a phylogenetic tree where a single ancestor splits into more than two descendant species | ||||
| Node (of a phylogenetic tree) | A point on a phylogenetic tree representing the common ancestor of descendant groups | ||||
| Branch (of a phylogenetic tree) | The evolutionary lineage or path between two nodes on a phylogenetic tree; indicates the divergence of species or groups from a common ancestor | ||||
| Root (of a phylogenetic tree) | The base of a phylogenetic tree, representing the most recent common ancestor of all taxa in the tree | ||||
| Genetic structure | The distribution of genotypes (combinations of alleles) in a population(i.e., how allele frequencies correspond to actual individual genetic makeup). | ||||
| Population genetics | The branch of biology that studies the frequencies of alleles and genotypes in populations, and how they change over time under influences like selection, drift, mutation and migration. | ||||
| Microevolution | Evolutionary change within a population or species (for example, shifts in allele frequencies from generation to generation). | ||||
| Macroevolution | Evolutionary change above the level of species, such as the origin of new species, large-scale patterns over long time frames. | ||||
| Modern synthesis | The mid‐20th-century integration of Darwin’s theory of natural selection and Mendelian genetics into a unified framework of how populations evolve genetically. | ||||
| Hardy-Weinberg principle (equilibrium) | A mathematical model stating that in a large, randomly-mating population, without mutation, migration, selection or drift, allele and genotype frequencies remain constant (i.e., no evolution occurs) from one generation to the next. | ||||
| Founder effect | A form of genetic drift that occurs when a small group of individuals becomes isolated from a larger population and the allele frequencies in the “founder” group differ from those in the original population, thus altering the gene pool. | ||||
| Genetic drift | Random changes in allele frequencies from one generation to the next, particularly in small populations, purely by chance rather than by natural selection. | ||||
| Bottleneck Effect | A type of genetic drift that happens when a population’s size is drastically reduced (for example, by a natural disaster or human activity), causing many alleles to be lost by chance. | ||||
| Mutation | A random change in the DNA sequence. As an evolutionary force, it creates new alleles (one of the forces that can alter allele frequencies in a population). | ||||
| Migration | (in population genetics): movement of alleles from one population into another via individuals or gametes, altering allele frequencies in the recipient population | ||||
| Fitness | (Darwinian fitness): The relative ability of an organism to survive and reproduce in its environment, contributing alleles to the next generation | ||||
| Stabilizing selection | A mode of natural selection in which intermediate phenotypes are favoured over extremes, reducing variation in the trait | ||||
| Directional selection | A mode of natural selection that shifts the overall phenotype in one direction by favouring an extreme phenotype over the current average. | ||||
| Diversifying selection | A mode of natural selection that favours two or more extreme phenotypes over intermediate ones — increasing variation and potentially leading toward speciation. (also known as disruptive selection) | ||||
| Anoxic | Lacking oxygen | ||||
| Stromatolite | A sedimentary structure produced when minerals are precipitated by microorganisms (often prokaryotes) in microbial mats; fossilized stromatolites provide evidence of ancient life | ||||
| Microbial Mat | A layered sheet of microorganisms (mostly prokaryotes) that may represent one of Earth’s earliest forms of life | ||||
| Prokaryotes | Single-celled organisms that lack a membrane-bound nucleus; they were the first forms of cellular life on Earth and include the domains Bacteria and Archaea | ||||
| Reproduction | The process by which organisms produce new individuals that inherit their genetic material. | ||||
| Homeostasis | The ability of living organisms to maintain a relatively stable internal environment (e.g., temperature, pH, chemical concentrations) despite external changes | ||||
| Bacteria | (Domain):One of the two major prokaryotic lineages, comprised of a vast diversity of organisms (including the phyla Proteobacteria, Cyanobacteria, Spirochaetes, and others) distinguished by cell‐wall chemistry, metabolism, and genetic features | ||||
| Archaea | (Domain): One of the two major prokaryotic lineages, differing from Bacteria in biochemistry (e.g., membrane lipids), genetics, and often living in extreme environments (though not exclusively). | ||||
| Metabolism | The sum of all chemical reactions within a cell or organism that manage the uptake, conversion, and use of energy and materials. It includes both catabolism (breaking down molecules to release energy) and anabolism (building complex molecules using energy) | ||||
| Extremophiles | Organisms (especially prokaryotes) adapted to live in extreme conditions (high/low temperature, high salinity, high acidity) — part of prokaryote diversity showing how wide their environmental tolerance can be | ||||
| Autotroph | An organism that produces its own organic molecules from inorganic sources, such as carbon dioxide, typically using energy from light or chemical reactions | ||||
| Heterotroph | An organism that obtains its organic molecules by consuming other organisms or organic matter | ||||
| Phototroph | An organism that uses light as its primary energy source | ||||
| Chemotroph | An organism that obtains energy by oxidizing chemical compounds, either organic or inorganic. | ||||
| Gram-positive bacteria | Bacteria that have thick peptidoglycan layers in their cell walls and retain the purple stain in Gram staining | ||||
| Gram-negative bacteria | Bacteria with thinner peptidoglycan layers and an outer membrane, which do not retain the purple Gram stain but take up a pink counterstain | ||||
| Binary fission | A form of asexual reproduction in prokaryotes where one cell divides into two identical daughter cells | ||||
| Plasmid | A small, circular DNA molecule separate from the main chromosome, often carrying genes that provide advantages like antibiotic resistance. | ||||
| Endospore | A resistant, dormant structure formed by some bacteria to survive harsh conditions | ||||
| Nitrogen fixation | The process by which certain prokaryotes convert atmospheric nitrogen (N2) into ammonia (NH3), a form usable by plants | ||||
| Biofilm | A community of microorganisms living together on a surface, embedded in a self-produced matrix of extracellular substances | ||||
| Nucleoid | The region in a prokaryotic cell where the circular chromosome is located (not membrane‑bound) | ||||
| Capsule | A gelatinous outer layer outside the cell wall of some prokaryotes that aids in surface attachment, resists dehydration, and can protect from being eaten by immune cells | ||||
| Pili | Hair‑like projections on a prokaryote’s surface used for attachment or DNA transfer during conjugation (singular: pilus) | ||||
| flagellum | A whip‑like appendage used for locomotion by some prokaryotes (plural: flagella) | ||||
| Peptidoglycan | A mesh‑like polymer of sugars and amino acids found in many bacterial cell walls, giving structural support. | ||||
| Macronutrients | Nutrients required in large amounts by an organism | ||||
| Micronutrients | Nutrients required in smaller amounts by an organism | ||||
| Transformation | A type of horizontal gene transfer where bacteria take up DNA from their environment | ||||
| Conjugation | A process where genetic material is exchanged between bacterial cells via direct contact, often using pili | ||||
| Transduction | Transfer of bacterial DNA from one cell to another by a virus (bacteriophage) | ||||
| Chemotaxis | Movement of an organism or cell toward (positive chemotaxis) or away from (negative chemotaxis) a chemical stimulus | ||||
| Thermophile | An organism adapted to live in high-temperature environments, usually above 45°C, such as hot springs or compost piles | ||||
| Cryophile | An organism adapted to very cold conditions, similar to psychrophiles, thriving in near-freezing environments (also called a psychrophile) | ||||
| Halophile | An organism that thrives in environments with very high salt concentrations, such as salt lakes or salt flats | ||||
| Phototaxis | Movement of an organism toward (positive phototaxis) or away from (negative phototaxis) a light source | ||||
| Thermotaxis | Movement of an organism toward (positive) or away from (negative) a temperature stimulus | ||||
| Antibiotic Resistance | The ability of a microbe to survive and grow in the presence of an antibiotic; often the result of genetic changes and selection in prokaryote populations | ||||
| Pathogen | A microorganism (such as a prokaryote) that can cause disease in a host organism. | ||||
| Bioremediation | The use of organisms (including prokaryotes) to remove or neutralize pollutants from a contaminated site (e.g., oil spills, toxic metals) | ||||
| Nitrogen cycle | The set of processes that convert nitrogen among different chemical forms (N₂, NH₄⁺, NO₃⁻, etc.) | ||||
| Carbon cycle | The movement of carbon through Earth’s major reservoirs (atmosphere, land, oceans, biomass, sediments), including conversion between CO₂ and organic carbon forms | ||||
| Nutrient cycling | The processes by which elements and compounds (like carbon and nitrogen) move through ecosystems, often between living and nonliving sources | ||||
| Decomposition | The breakdown of dead organic matter by microorganisms, including prokaryotes, releasing nutrients back into the environment | ||||
| Parasitism | A symbiotic relationship where one organism (the parasite) benefits at the expense of the other (the host) | ||||
| Amensalism | A biological interaction where one organism is harmed or inhibited while the other is unaffected | ||||
| Commensalism | A symbiotic relationship where one species benefits and the other is neither helped nor harmed | ||||
| Anaerobic respiration | A form of respiration using molecules other than oxygen as the final electron acceptor | ||||
| Aerobic respiration | Respiration that uses oxygen as the final electron acceptor to produce energy | ||||
| Methanogen | A type of Archaea that produces methane as a metabolic byproduct under anaerobic conditions | ||||
| Saprotroph/saprobe | An organism that feeds on dead or decaying organic matter, playing a key role in nutrient recycling | ||||
| Endosymbiosis | A relationship where one organism lives inside the cells of another, such as the origin of mitochondria and chloroplasts | ||||
| Microbiome | The community of microorganisms living in a particular environment, such as the human gut | ||||