Biology

An action potential is a brief, regenerative change in membrane voltage that transmits signals in electrically excitable cells.

Adaptive immunity is antigen-specific defense mediated by B and T lymphocytes, characterized by diverse receptors, selective expansion, and immunological memory.

Affinity maturation improves antibody binding during an immune response through mutation of antibody genes and selection of B cells with higher-affinity receptors.

An antibody is an immunoglobulin protein produced by B cells that recognizes specific antigens and supports immune defense.

A substance specifically recognized by antibodies or lymphocyte receptors, whether or not it independently induces an immune response.

Apoptosis is a regulated form of cell death that removes unwanted or damaged cells through coordinated molecular pathways and cellular dismantling.

Autoimmune regulator (AIRE) is a transcriptional regulator that promotes immune tolerance by enabling thymic cells to express diverse self-antigens.

An axon is a specialized neuronal projection that conducts electrical signals and delivers them to other neurons, muscles, or glands.

A B cell is an adaptive immune lymphocyte that recognizes antigens and can develop into an antibody-secreting plasma cell or a memory B cell.

A class of organic compounds comprising sugars, their polymers, and related derivatives, with roles in energy metabolism, biological structure, and molecular recognition.

The citric acid cycle is a central metabolic pathway that oxidizes acetyl groups, supplies electrons for ATP production, and provides intermediates for biosynthesis.

Class-switch recombination changes an antibody’s heavy-chain constant region, altering its effector functions while retaining its rearranged antigen-binding region.

The complement system is a regulated network of immune proteins that marks targets for removal, promotes inflammation, and damages susceptible microbial membranes.

A cytokine is a signaling protein that coordinates immune responses and regulates cell activation, growth, differentiation, and survival.

DNA polymerases are enzymes that synthesize DNA, supporting genome replication, DNA repair, and laboratory methods such as amplification and sequencing.

DNA repair comprises cellular mechanisms that correct DNA damage and replication errors, helping preserve genetic information.

An electrochemical gradient combines chemical and electrical potential differences, determining the energetic direction of ion movement and powering cellular processes.

An erythrocyte is a red blood cell specialized for transporting oxygen and participating in carbon dioxide transport between respiratory organs and tissues.

Fermentation is an energy-yielding metabolic process and, more broadly, the controlled microbial transformation of materials into useful products.

Flow cytometry measures individual cells or particles in a flowing suspension, using light scattering and fluorescence to characterize populations and, in some instruments, separate them.

A germinal center is a specialized lymphoid structure where activated B cells diversify their antibodies, undergo selection, and generate cells supporting lasting immunity.

Glycolysis is a metabolic pathway that converts glucose into pyruvate, generating ATP and NADH without directly requiring oxygen.

Hematopoiesis is the regulated production of blood cells and platelets from stem and progenitor cells throughout development and adult life.

Homologous recombination exchanges or copies information between similar DNA sequences, supporting DNA repair, chromosome inheritance, and genetic variation.

A hormone is a biological chemical messenger that coordinates cellular activity, growth, metabolism, reproduction, and responses to changing conditions.

Immunological memory is the persistence of immune changes after antigen exposure that enables faster, more effective responses upon subsequent encounters.

Innate immunity comprises rapid, inherited defense mechanisms that detect microbes, restrict infection, and help initiate adaptive immune responses.

A membrane protein that forms a selective pore through which ions move, enabling electrical signaling, secretion, sensory detection, and cellular regulation.

A leukocyte, or white blood cell, is an immune-system cell involved in defending the body against infection and coordinating immune responses.

A macrophage is a tissue-associated immune cell that engulfs microbes and cellular debris, coordinates immune responses, and supports tissue maintenance and repair.

The major histocompatibility complex is a gene region encoding immune proteins, especially molecules that present peptide antigens to T cells.

Membrane potential is the electrical potential difference across a biological membrane, arising from ion gradients and selective permeability and supporting electrical signaling, transport, and energy conversion.

A memory B cell is a long-lived, antigen-experienced lymphocyte that supports a rapid antibody response when a previously encountered antigen returns.

Metabolism is the coordinated network of chemical reactions through which living organisms obtain energy, build cellular components, and maintain biological functions.

A neutrophil is a granular white blood cell that rapidly responds to infection and tissue injury through migration, phagocytosis, and antimicrobial activity.

A DNA repair pathway that reconnects double-strand breaks without requiring an extensive homologous template.

Opsonization is the coating of a target with molecules that enhance its recognition and uptake by phagocytic immune cells.

Oxidative phosphorylation couples respiratory electron transfer to ATP synthesis through an electrochemical gradient across a biological membrane.

Peptidoglycan is a mesh-like polymer of sugars and short peptides that strengthens most bacterial cell walls and is continually rebuilt during growth and division.

Phagocytosis is the cellular engulfment of large particles, supporting nutrition, immune defense, and the removal of dead cells and tissue debris.

Plankton are aquatic organisms that drift with currents, supporting food webs, recycling nutrients, and contributing to global carbon cycling.

A plasma cell is a differentiated B lymphocyte specialized for antibody secretion, contributing to immediate defense and long-term humoral immunity.

Proton-motive force is the electrochemical potential difference across a membrane that drives proton transport, ATP synthesis, and other cellular processes.

Receptor editing changes antigen-receptor specificity through additional gene rearrangements, helping developing B cells avoid self-reactivity.

Recombinant DNA consists of DNA segments joined through laboratory methods and is used to study genes, produce biological products, and engineer organisms.

Somatic hypermutation introduces mutations into antibody genes in activated B cells, supplying variation for affinity maturation.

Starch is a glucose-based carbohydrate that stores energy in plants and serves as a major food component and industrial raw material.

A T cell is a thymus-maturing immune cell that recognizes antigens, coordinates immune responses, kills abnormal cells, and contributes to immune memory and tolerance.

The T-cell receptor is a membrane-bound protein complex that enables T cells to recognize antigens and initiate immune signaling.

V(D)J recombination assembles antigen-receptor genes in developing lymphocytes, generating much of the diversity required for adaptive immunity.