BIO - TERMS - FREQUENCY > 2 PT 1 Flashcards
action potential
A brief fluctuation in membrane potential caused by the rapid opening and closing of voltage-gated ion channels; also known as spike, nerve impulse, or discharge. Action potentials sweep like a wave along axons to transfer information from one place to another in the nervous system. // Rapid, transient, self-propagating electrical excitation in the plasma membrane of a cell such as a neuron or muscle cell. Action potentials, or nerve impulses, make possible long-distance signaling in the nervous system. // Self-propagating change in membrane potential occurring in excitable cells (e.g., neurons, muscle cells).
acute-phase proteins // acute-phase reactants
Proteins with innate immune function whose production is increased in the presence of an infection (the acute-phase response). They circulate in the blood and participate in early phases of host defense against infection. An example is mannose-binding lectin. // Serum proteins whose concentration changes by at least 25% during inflammation. // Plasma proteins whose levels are elevated or reduced within 1 to 2 days of an acute stress.
adaptor protein // adaptor
General term for a protein that functions solely to link two or more different proteins together in an intracellular signaling pathway or protein complex. // Signaling proteins, generally without their own enzymatic activities, that have binding sites for two or more cellular components and serve to bring those components together. // Nonenzymatic proteins that form physical links between members of a signaling pathway, particularly between a receptor and other signaling proteins. They recruit members of the signaling pathway into functional protein complexes.
adjuvant
A substance added to a vaccine to increase its effectiveness. // A compound or mixture that stimulates immune responses to an antigen (Chapter 8) // Any substance that enhances the immune response to an antigen with which it is mixed.
aerobic respiration // aerobic cellular respiration
Breakdown of nutrients (e.g., pyruvate, fatty acids) to produce ATP, water, and carbon dioxide. The process requires oxygen. // Process by which a cell obtains energy from sugars or other organic molecules by allowing their carbon and hydrogen atoms to combine with the oxygen in air to produce CO2 and H2O, respectively. // Respiration in which the final electron acceptor in the electron transport chain is molecular oxygen (O2).
albumin
A plasma protein that accounts for approximately 60% of the total plasma protein. // (al-bū′min) Plasma protein important in regulating fluid balance. // A blood protein that is water soluble and carries a variety of salt and nutrients; it helps to maintain osmotic pressure of the blood.
alkaloid
Organic bases found in plants; they are often poisonous. // A chemical substance containing nitrogen as part of a heterocyclic ring structure; often highly toxic or mind-altering. Alkaloids represent a diverse array of amino-acid-derived, often highly complex structures with potential effects on mammalian organisms. Used in medicine and pharmacy. // Naturally occurring organic bases, such as morphine.
allergen
An antigen that evokes a hypersensitivity response. // (al′er-gen) Noninfectious substance that elicits an excessive response by the immune system (allergic reaction). // Any antigen that elicits an allergic reaction.
anaerobe
An organism that lives without oxygen. Obligate anaerobes die when exposed to oxygen. // An organism that does not require molecular oxygen (O2) for growth. // Organisms that do not use oxygen as terminal electron acceptor.
angiotensin II
(an′jē-ō-ten′sin) A peptide hormone, derived from angiotensin I, that increases blood pressure. // A product of angiotensin I that is produced in the lung by angiotensin-converting enzyme. Production of angiotensin II results in the release of aldosterone from the adrenal cortex and antidiuretic hormone from the pituitary gland. // The active form of the vasoconstrictor angiotensin.
antibiotic
An antimicrobial agent, usually produced naturally by a bacterium or fungus. // One of many different organic compounds that are formed and secreted by various species of microorganisms and plants, are toxic to other species, and presumably have a defensive function. // A substance that kills or inhibits the growth of microorganisms.
antigen-presenting cell (APC)
A macrophage, dendritic cell, or B cell that engulfs an antigen and presents fragments to T cells. // Immune cell that presents (displays) an antigen to T-lymphocytes; e.g., a macrophage. // Highly specialized cells that can process antigens and display their peptide fragments on the cell surface together with other, co-stimulatory, proteins required for activating naive T cells. The main antigen-presenting cells for naive T cells are dendritic cells, macrophages, and B cells.
apoptosome
A large, multimeric protein structure that forms in the process of apoptosis when cytochrome c is released from mitochondria and binds Apaf-1. A heptamer of cytochrome c-Apaf-1 heterodimers assembles into wheel-like structure that binds and activates procaspase-9, an initiator caspase, to initiate the caspase cascade. // Heptamer of Apaf1 proteins that forms on activation of the intrinsic apoptotic pathway; it recruits and activates initiator caspases that subsequently activate downstream executioner caspases to induce apoptosis. // A cytoplasmic protein complex that activates caspases, causing apoptosis.
atom
A submicroscopic particle that constitutes the fundamental building block of ordinary matter; the smallest identifiable unit of an element. // The smallest particle that displays properties of an element; composed of electrons, protons, and neutrons (except in hydrogen). // The smallest unit of matter that can enter into a chemical reaction.
base excision repair
DNA repair pathway in which single faulty bases are removed from the DNA helix and replaced. Compare nucleotide excision repair. // Removal of an abnormal base by a DNA glycosylase. // The removal of abnormal or chemically modified bases from DNA.
basement membrane
Thin mat of extracellular matrix that separates epithelial sheets, and many other types of cells such as muscle or fat cells, from connective tissue. Also called basal lamina. // An extracellular matrix structure beneath single-layered epithelia. // Selective molecular layer that attaches epithelial tissue to underlying connective tissue.
bioinformatics
The computerized analysis of biological data, using methods derived from statistics, linguistics, mathematics, chemistry, biochemistry, and physics. The data are often nucleic acid or protein sequence or structural data, but can also involve experimental data from many sources, patient statistics, and materials in the scientific literature. Bioinformatics research focuses on methods for data storage, retrieval, and analysis. // The science of determining the function of genes through computer-assisted analysis. // The study of genetic and other biological information using computer and statistical techniques.
Bond dissociation energy, D // bond energy
The amount of energy needed to break a bond and produce two radical fragments. // The energy required to break a bond. // The energy required to break 1 mol of the bond in the gas phase.
calmodulin
Ubiquitous intracellular Ca2+-binding protein that undergoes a large conformation change when it binds Ca2+, allowing it to regulate the activity of many target proteins. In its activated (Ca2+-bound) form, it is called Ca2+/calmodulin. // Calcium-binding protein that is activated by binding Ca2+; it is then able to bind to and regulate the activity of a wide variety of enzymes. // A calcium-dependent enzyme activator.
carbonic anhydrase
An enzyme that establishes equilibrium among carbon dioxide, water, and carbonic acid. // Enzyme that reversibly catalyzes the formation of carbonic acid (H2CO3) from CO2 and H2O. cardiac output Product of stroke volume multiplied by heart rate in a minute (e.g., 5 L/min). // The enzyme that converts carbon dioxide and water to carbonic acid.
carcinoma
A cancer derived from epithelial tissue. // Cancer of epithelial cells. The most common form of human cancer. // Cancer of epithelial tissues.
catabolite repression
Inhibition of the metabolism of alternative carbon sources by glucose. // Glucose-mediated reduction in the rates of transcription of operons that specify enzymes involved in catabolic pathways (such as the lac operon). // Repression of catabolic operons in the presence of glucose.
cell cycle (cell-division cycle)
Th e orderly and reproducible sequence in which cells increase in size, duplicate the genome, segregate duplicated chromosomes, and divide. (Chapter 6) // The cyclical events that occur during the divisions of mitotic cells. The cell cycle oscillates between mitosis and the interphase, which is divided into G1, S, and G2. // Reproductive cycle of a cell: the orderly sequence of events by which a cell duplicates its chromosomes and, usually, the other cell contents, and divides into two.
cellulose
Long, unbranched chains of glucose; major constituent of plant cell walls. // A polysaccharide that consists of glucose units bonded together by b-glycosidic linkages; the main structural component of plants, and the most abundant organic substance on Earth. // Fiber component and main structural polysaccharide in plant cell walls that is composed of repeating glucose units with a b1–4 linkage.
cerebral cortex
(se-rē′bral kor′teks) Superficial layer of gray matter in the cerebrum. // Outermost layer of the hemispheres of the brain; the most complex structure in the human body. // The layer of gray matter that lies just under the surface of the cerebrum.
cholecalciferol (or vitamin D3)
The form of vitamin D that is made photochemically in the skin. // Formed in the skin when 7-dehydrocholesterol is exposed to UV light. // Accepted designation for cholecalciferol (a vitamin D-active substance derived from animal sterols)
chromatography
A process in which complex mixtures of molecules are separated by many repeated partitionings between a flowing (mobile) phase and a stationary phase. // A method for separating and identifying the components from mixtures of molecules having similar chemical and physical properties. // A technique for separating a mixture of compounds into pure components. Different compounds adsorb to a stationary support phase and are then carried along it at different rates by a mobile phase.
circadian clock // circadian rhythm
Internal cyclical process that produces a particular change in a cell or organism with a period of around 24 hours, for example the sleep-wakefulness cycle in humans. // Any rhythm with a period of about 1 day. // Th e cycle (roughly 24 hours in humans) that regulates many physiological processes, such as sleep-wake cycles. (Chapter 1)
clonal selection
From a population of T and B lymphocytes with a vast repertoire of randomly generated antigen-specific receptors, a given foreign antigen activates (selects) only those lymphocyte clones that display a receptor that fits the antigen. Explains how the adaptive immune system can respond to millions of different antigens in a highly specific way. // Selective growth stimulation by an antigen of a B-cell clone carrying a matching surface antibody. // The development of clones of B and T cells against a specific antigen.
Coding strand (sense strand)
In DNA transcription, the DNA strand identical in base sequence to the RNA transcribed from it, with U in the RNA in place of T in the DNA; as distinct from the template strand. Also called the nontemplate strand. // The sense strand of double-helical DNA that contains the gene. // The strand of a gene whose base sequence corresponds to the base sequence of the RNA transcript.
commensalism
A symbiotic relationship in which two organisms live in association and one is benefited while the other is neither benefited nor harmed. // Ecological relationship between microbes and their host in which the microbe benefits but offers no benefit and causes no harm. // Relationship between two species in which one organism benefits and the other species is unaffected.
complement system
A set of blood plasma proteins that act in a concerted fashion to destroy extracellular pathogens and infected cells; originally defi ned as a heat-labile activity that lysed bacteria in the presence of antibody (it “complemented” antibody action); the activated complement pathway also stimulates phagocytosis, chemotaxis, and infl ammation. (Chapter 4) // A set of plasma proteins that act together as a defense against pathogens in extracellular spaces. The pathogen becomes coated with complement proteins that facilitate its removal by phagocytes and that can also kill certain pathogens directly. Activation of the complement system can be initiated in several different ways. See classical pathway, alternative pathway, lectin pathway. // System of blood proteins that can be activated by antibody–antigen complexes or pathogens to help eliminate the pathogens, by directly causing their lysis, by promoting their phagocytosis, or activating an inflammatory response.
condensation reaction
A chemical reaction in which a molecule of water is released; also called dehydration synthesis. // A reaction in which two or more organic compounds are joined, often with the loss of water or some other small molecule. // Bond formation with release of a water molecule.
confocal microscope // confocal microscopy
Type of light microscope that produces a clear image of a given plane within a solid object. It uses a laser beam as a pinpoint source of illumination and scans across the plane to produce a two-dimensional “optical section.” // A light microscope that uses fluorescent stains and laser to make two- and three-dimensional images. // Optical imaging technique increasing optical resolution and contrast of a microscopic picture based on the elimination of out-of-focus light in specimens that are thicker than the focal plane or depth of focus generated by the objective.
conjugate acid-base pair // conjugate redox pair
A proton donor and its corresponding deprotonated species; for example, acetic acid (donor) and acetate (acceptor). // Two substances related to each other by the transfer of a proton. // An electron donor and its corresponding electron acceptor form; for example, Cu (donor) and Cu2 (acceptor), or NADH (donor) and NAD (acceptor).
cooperativity
The characteristic of an enzyme or other protein in which binding of the first molecule of a ligand changes the affinity for the second molecule. In positive cooperativity, the affinity for the second ligand molecule increases; in negative cooperativity, it decreases. // Interactions between multiple binding sites for the same ligand in an allosteric protein. // The property of long-term potentiation, reflecting the requirement that many inputs be active at the same time during a tetanus to induce LTP. See also long-term potentiation.
cortisol
A corticosteroid hormone released from the adrenal cortex that stimulates the catabolism of proteins, the sparing of glucose utilization, an increase in gluconeogenesis, and an increase in free fatty acid mobilization. // A steroid hormone released by the adrenal cortex; mobilizes energy reserves, suppresses the immune system, and has direct actions on some CNS neurons. // The most important glucocorticoid; a stress hormone.
crista (plural cristae)
A specialized invagination of the inner mitochondrial membrane. // Folding of the inner membrane of a mitochondrion. // Infoldings of the inner mitochondrial membrane.
Crossing over
A process in which chromosomes exchange material through the breakage and reunion of their DNA molecules. (See also Recombination.) // The process by which a portion of one chromosome is exchanged with a portion of another chromosome. // The exchange of DNA between homologous chromosomes during meiosis and (rarely) mitosis.
cyclin
One of a family of proteins that activate cyclin-dependent protein kinases and thereby regulate the cell cycle. // Protein that periodically rises and falls in concentration in step with the eukaryotic cell cycle. Cyclins activate crucial protein kinases (called cyclin-dependent protein kinases, or Cdks) and thereby help control progression from one stage of the cell cycle to the next. // Activators of cyclin-dependent protein kinases.
cytopathic effect (CPE)
Deleterious morphological changes induced in cells by viral infection. (Chapter 3) // A visible effect on a host cell, caused by a virus, that may result in host cell damage or death. // The morphological changes induced in cells by viral infection. (Chapter 2)
dalton (da)
The mass of a hydrogen atom. // Unit of atomic or molecular weight; 1 dalton (Da) is the weight of a hydrogen atom (1.66 x 10⁻²⁴ g). // The measure of molecular mass; equals 1g/mole.
dendritic cell (DC)
Phagocytic cells of the skin and mucous membranes. // A type of antigen-presenting cell characterized by long fingerlike extensions; found in lymphatic tissue and skin. // Bone marrow-derived cells found in most tissues, including lymphoid tissues. There are two main functional subsets. Conventional dendritic cells take up antigen in peripheral tissues, are activated by contact with pathogens, and travel to the peripheral lymphoid organs, where they are the most potent stimulators of T-cell responses. Plasmacytoid dendritic cells can also take up and present antigen, but their main function in an infection is to produce large amounts of the antiviral interferons as a result of pathogen recognition through receptors such as TLRs. Both these types of dendritic cells are distinct from the follicular dendritic cell that presents antigen to B cells in lymphoid follicles.
desmosome
(dez′mō-sōm) One type of adhesion between two epithelial cells; a type of intercellular junction that holds cells together at a single point (like a button). // Anchoring cell–cell junction, usually formed between two epithelial cells. Characterized by dense plaques of protein into which intermediate filaments in the two adjoining cells insert. // Spot welds that hold neighboring cells together.
disulfide bond
A covalent bond involving the oxidative linkage of two Cys residues, from the same or different polypeptide chains, forming a cystine residue. // A covalent bond formed by an oxidative reaction between two sulfhydryl groups. // A covalent bond that holds together two atoms of sulfur. DNA base composition The moles-percentage of guanine plus cytosine in an organism’s DNA.
domain // protein domain
A distinct structural unit of a polypeptide; domains may have separate functions and may fold as independent, compact units. // A taxonomic classification based on rRNA sequences; above the kingdom level. // Portion of a protein that has a tertiary structure of its own. Larger proteins are generally composed of several domains, each connected to the next by short flexible regions of polypeptide chain. Homologous domains are recognized in many different proteins.
electrochemical gradient
Combined influence of a difference in the concentration of an ion on two sides of a membrane and the electrical charge difference across the membrane (membrane potential). Ions or charged molecules can move passively only down their electrochemical gradient. // Electrical charge difference across a membrane. // The resultant of the gradients of concentration and of electric charge of an ion across a membrane; the driving force for oxidative phosphorylation and photophosphorylation.
Electronegativity (EN)
An atom’s ability to attract electrons to itself in a covalent bond. // The tendency of an atom to attract electrons. // The ability of an atom to attract electrons in a covalent bond. Electronegativity increases across the periodic table from left to right and from bottom to top.
embryonic stem cell (ESC // ES cell)
A cell from an embryo that has the potential to become a wide variety of specialized cell types. // Cells derived from the inner cell mass of the early mammalian embryo. Capable of giving rise to all the cells in the body. Can be grown in culture, genetically modified, and inserted into a blastocyst to develop a transgenic animal. // Cells present in embryos that can differentiate into many different types of tissues and/or organs.
endosome
Cell structures that transport a variety of compounds to either lysosomes for degradation or to the cell membrane surface for recycling. // An organelle derived from endocytic vesicles. // A vesicle that transports molecules from the plasma membrane to the cell interior. (Chapter 5)
enthalpy (H)
The energy content of a molecule. // The sum of the internal energy of a system and the product of its pressure and volume. // The heat content of a system.
epidermis
Epithelial layer covering the outer surface of the body. Has different structures in different animal groups. The outer layer of plant tissue is also called the epidermis. // (ep-i-derm′is) The epithelium (keratinized, stratified squamous) of the integument. // The outer portion of the skin.
epinephrine
A catecholamine neurotransmitter synthesized from norepinephrine; also called adrenaline. // (ep′i-nef′rin) Hormone released by the adrenal medulla during activation of the sympathetic nervous system. // Synonym for adrenaline, a stress hormone from the adrenal medulla.
essential amino acid
An amino acid needed for health and maintenance and that must be ingested because the tissues of the body cannot synthesize it. // One of nine amino acids that are biosynthesized only in plants and microorganisms and must be obtained by humans in the diet. // Amino acids that cannot be synthesized by humans (and other vertebrates) and must be obtained from the diet.
extracellular matrix (ECM)
(mā′triks) Protein fibers and ground substance in the extracellular space of connective tissue. // The network of fibrous proteins deposited in the space between cells. // An interwoven combination of glycosaminoglycans, proteoglycans, and proteins, just outside the plasma membrane, that provides cell anchorage, positional recognition, and traction during cell migration.
family // family (group)
A group of organic compounds with the same functional group. // A taxonomic group between order and genus. // Columns within the main-group elements in the periodic table that contain elements that exhibit similar chemical properties.
ferritin
A large and complex molecule consisting of 24 polypeptides that functions to store 4,500 atoms of iron for each molecule. // One of several human iron-binding proteins that reduce iron available to a pathogen. // The principal intracellular iron storage protein; trace amounts are present in the plasma.
fibrinogen
The inactive precursor protein of fibrin. // A protein produced by the liver that forms a fibrin clot following the action of prothrombin. // The circulating precursor of fibrin.
fibrous protein
A protein with a relatively linear structure; fibrous proteins tend to be insoluble in aqueous solutions. // Insoluble proteins that serve a protective or structural role; contain polypeptide chains that generally share a common secondary structure. // A type of protein that consists of polypeptide chains arranged side by side in long threads. Such proteins are tough, insoluble in water, and used in nature for structural materials such as hair, hooves, and ingernails.
fluid mosaic model
A model describing biological membranes as a fluid lipid bilayer with embedded proteins; the bilayer exhibits both structural and functional asymmetry. // A way of describing the dynamic arrangement of phospholipids and proteins comprising the plasma membrane. // A model of membrane structure that assumes globular proteins are embedded in a lipid bilayer.
Fluorescence resonance energy transfer (also Förster resonance energy transfer both abbreviated with FRET)
Mechanism that describes the nonradiative energy transfer between two fluorophores; prerequisites for energy transfer from donor fluorophore to acceptor fluorophore are the small distance between both (Förster radius) and the spectral overlap of the donor emission spectrum and the acceptor absorption spectrum. // Technique for monitoring the closeness of two fluorescently labeled molecules (and thus their interaction) in cells. Also known as Förster resonance energy transfer. // A technique for estimating the distance between two proteins or two domains of a protein by measuring the nonradiative transfer of energy between reporter chromophores when one is excited and the fluorescence emitted from the other is quantified.
fungus (plural fungi)
A kingdom of single-celled and multicellular eukaryotic organisms, including the yeasts and molds, that can cause a variety of diseases. Immunity to fungi is complex and involves both humoral and cell-mediated responses. // Kingdom of eukaryotic organisms that includes the yeasts, molds, and mushrooms. Many plant diseases and a relatively small number of animal diseases are caused by fungi. // An organism that belongs to the Kingdom Fungi; a eukaryotic absorptive chemoheterotroph.
futile cycle
A biochemical reaction cycle that is wasting energy, e.g., a simultaneous action of a kinase generating a phosphorylated intermediate that is subsequently and immediately degraded by a phosphatase. // A cycle of enzyme-catalyzed reactions that results in release of thermal energy by the hydrolysis of ATP. // Simultaneous activity of two opposing metabolic reactions, leading to ATP hydrolysis.
gap junction
Communicating channel-forming cell–cell junction present in most animal tissues that allows ions and small molecules to pass from the cytoplasm of one cell to the cytoplasm of the next. // A small aqueous channel connecting the cytoplasm of neighboring cells. // A specialized junction where a narrow gap between two cells is spanned by protein channels (connexons) that allow ions to pass directly from one cell to another.
gene therapy
Treating a disease by replacing abnormal genes. // The introduction of a functional gene into the patient’s cells. // The treatment of inherited diseases by introducing wild-type copies of the defective gene causing the disorder into the cells of affected individuals. If reproductive cells are modified, the procedure is called germ-line or heritable gene therapy. If cells other than reproductive cells are modified, the procedure is called somatic-cell or noninheritable gene therapy.
genomic library
A DNA library containing DNA segments that represent all (or most) of the sequences in an organism’s genome. // Collection of cloned DNA molecules representing an entire genome. // A collection of cloned DNA fragments created by inserting restriction enzyme fragments in a bacterium, yeast, or phage.
globular protein
A protein that folds into a roughly spherical shape so that its polar side chains are oriented outward and its nonpolar side chains, toward the interior; globular proteins tend to be soluble in water. // A type of protein that is coiled into a compact, nearly spherical shape. Globular proteins, which are generally water-soluble and mobile within the cell, are the structural class to which enzymes belong. // Soluble proteins with a globular (somewhat rounded) shape.
glucose
(glū′kōs) A monosaccharide; primary nutrient source for cellular respiration. // The most abundant monosaccharide in food carbohydrate and the primary carbohydrate that circulates in the blood. // The most common mechanism for transporting carbohydrates in the body; primarily broken down by the glycolytic energy system.
