BIO - TERMS - FREQUENCY > 1 PT 9 Flashcards
accommodation
The focusing of light by changing the shape of the eye’s lens. // (ā-kom′ŏ-dā′shŭn) Changing the lens shape in order to focus on a nearby object.
adenosine deaminase (ADA) deficiency
A cause of severe combined immunodeficiency. // An inherited defect characterized by nonproduction of the enzyme adenosine deaminase, which leads to the accumulation of toxic purine nucleosides and nucleotides in cells, resulting in the death of most developing lymphocytes within the thymus. It is a cause of severe combined immunodeficiency. adhesins Cell-surface proteins on bacteria that enable them to bind to the surfaces of host cells.
AIRE (autoimmune regulator)
A protein expressed by a subpopulation of epithelial cells in the thymus that stimulates the production of small amounts of self proteins characteristic of other organs, exposing developing thymocytes to these proteins for the purpose of self-tolerance. // Gene encoding a protein (autoimmune regulator) that is involved in the expression of numerous genes by thymic medullary epithelial cells, enabling developing T cells to be exposed to self proteins characteristic of other tissues, thereby promoting tolerance to these proteins. Deficiency of AIRE leads to an autoimmune disease, APECED.
alpha (α) decay
The form of radioactive decay that occurs when an unstable nucleus emits a particle composed of two protons and two neutrons.
amplitude
The vertical height of a crest (or depth of a trough) of a wave; a measure of wave intensity. // The height of a wave measured from the midpoint to the maximum. The intensity of radiant energy is proportional to the square of the wave’s amplitude.
anterior
Toward the front of the body. // An anatomical reference meaning toward the nose or rostral.
apical
(ap′i-kăl) Related to the tip or extremity of a conical or pyramidal structure; opposite of basal. // Referring to the tip of a cell, a structure, or an organ. The apical surface of an epithelial cell is the exposed free surface, opposite to the basal surface. The basal surface rests on the basal lamina that separates the epithelium from other tissue.
astrocyte
(as′trō-sı̄t) Largest and most abundant glial cell of the central nervous system. // A glial cell in the brain that supports neurons and regulates the extracellular ionic and chemical environment.
autograft
A tissue graft from one’s self. // A graft of tissue from one site to another on the same individual. autoimmune disease Disease in which the pathology is caused by adaptive immune responses to self antigens.
B-cell antigen receptor, B-cell receptor (BCR)
The transmembrane immunoglobulin protein on the surface of a B cell that serves as its receptor for antigen. // The cell-surface receptor on B cells for specific antigen. It is composed of a transmembrane immunoglobulin molecule (which recognizes antigen) associated with the invariant Igα and Igβ chains (which have a signaling function). On activation by antigen, B cells differentiate into plasma cells producing antibody molecules of the same antigen specificity as this receptor.
beta-catenin (β-catenin)
Multifunctional cytoplasmic protein involved in cadherin-mediated cell–cell adhesion, linking cadherins to the actin cytoskeleton. Can also act independently as a transcription regulatory protein. Has an important role in animal development as part of a Wnt signaling pathway.
blood pressure
The pressure of blood against the vessel walls. // Measure of the force of blood pushing against the blood vessel wall; commonly measured in the brachial artery.
calnexin
Carbohydrate-binding chaperone protein in the endoplasmic reticulum (ER) membrane that binds to oligosaccharides on incompletely folded proteins and retains them in the ER. // A chaperone protein in the endoplasmic reticulum (ER) that binds to partly folded members of the immunoglobulin superfamily of proteins and retains them in the ER until folding is complete.
Carboxylic acids, RCO2H
Compounds containing the -CO2H functional group. // An organic acid containing the functional group — COOH.
cell-adhesion molecule (CAM)
A molecule on the cell surface that causes cells to adhere to one another. // Cell-surface proteins of several different types that mediate the binding of one cell to other cells or to extracellular matrix proteins. Integrins, selectins, and members of the immunoglobulin gene superfamily (such as ICAM-1) are among the cell-adhesion molecules important in the operation of the immune system.
chemiosmotic coupling (chemiosmosis)
Coupling of ATP synthesis to electron transfer via a transmembrane difference in charge and pH. // Mechanism in which an electrochemical proton gradient across a membrane (composed of a pH gradient plus a membrane potential) is used to drive an energy-requiring process, such as ATP production or the rotation of bacterial flagella.
cholecystokinin (CCK)
Hormone released from the duodenum in response to lipid-rich chyme; stimulates secretion from the pancreas and gallbladder. // A peptide found within some neurons of the central and peripheral nervous systems and in some endothelial cells lining the upper gastrointestinal tract; a satiety signal that inhibits feeding behavior, in part, by acting on axons of the vagus nerve that respond to gastric distension.
Classical pathway
One of three complement pathways that lead to activation of C3-C5 convertases; activation occurs by direct interaction of C1q or C3b proteins with a viral protein/antibody complex on the surface of an infected cell or a virus particle. (Chapter 3) // The complement-activation pathway that is initiated by C1 binding either directly to bacterial surfaces or to antibody bound to the bacteria, thus flagging the bacteria as foreign. See also alternative pathway, lectin pathway.
Colony
A compact collection of cells produced by the division of a single progenitor cell. // A visible mass of microbial cells arising from one cell or from a group of the same microbes.
conjugate acid
Any base to which a proton has been added. // The product that results from protonation of a Brønsted–Lowry base.
Contig
A set of overlapping clones that provide a physical map of a portion of a chromosome. // A series of overlapping clones or a continuous sequence defining an uninterrupted section of a chromosome.
cross-presentation
A process in which extracellular proteins taken up by specialized dendritic cells can give rise to peptides that can be presented by class I MHC proteins to cytotoxic T cells. // The process by which extracellular proteins taken up by dendritic cells can give rise to peptides presented by MHC class I molecules. It enables antigens from extracellular sources to be presented by MHC class I molecules and activate CD8 T cells.
decarboxylation
The removal of CO2 from an amino acid. // The loss of carbon dioxide from a molecule. β-Keto acids decarboxylate readily on heating.
dextrorotatory
Capable of rotating the plane of polarization of light clockwise. // A word used to describe an optically active substance that rotates the plane of polarization of plane-polarized light in a right-handed (clockwise) direction.
dipole moment (μ)
A measure of the separation of positive and negative charge in a molecule. // A measure of the net polarity of a molecule. A dipole moment arises when the centers of mass of positive and negative charges within a molecule do not coincide.
DNA library
A collection of cloned DNA fragments. // Collection of cloned DNA molecules, representing either an entire genome (genomic library) or complementary DNA copies of the mRNA produced by a cell (cDNA library).
duodenum
(dū-ō-dē′nŭm, dū-od′ĕ-nŭm) First section of small intestine. // First of three segments in the small intestine. Major site of absorption of nutrients.
elastic fiber
Extensible fiber formed by the protein elastin in many animal connective tissues, such as in skin, blood vessels, and lungs, which gives them their stretchability and resilience. // Protein that allows tissues to stretch and return to their original shape; located within connective tissues.
electroporation
A technique by which DNA is inserted into a cell using an electrical current. // A process whereby cell membranes are made permeable to DNA by applying an intense electric current.
endothelial cell
Cell type that forms the endothelium, the epithelium of a blood vessel wall. // Flattened cell type that forms a sheet (the endothelium) lining all blood and lymphatic vessels.
ergot
A toxin produced in sclerotia by the fungus Claviceps purpurea that causes ergotism. // A fungus (Claviceps purpurea) that infects grasses (especially rye) and produces pharmacologically active alkaloids.
extension
(eks-ten′shŭn) Movement of a joint in an anteriorposterior plane that increases the articulating angle. // The direction of movement that opens a joint. extensor A muscle that causes extension when it contracts.
Fc receptor
Family of cell-surface receptors that bind the Fc portions of different immunoglobulins: Fcγ receptors bind IgG, for example, and Fcε receptors bind IgE. // One of a family of cell-surface receptors that bind the tail region (Fc region) of an antibody molecule. Different Fc receptors are specific for different classes of antibodies, such as IgG, IgA, or IgE.
Flavonoid
Reported to reduce capillary fragility, and inhibit in vitro aldolase reductase (has a role in diabetic cataracts) and o-methyltransferase (inactivates epinephrine and norepinephrine) // A class of plant secondary metabolites that are composed of two aromatic rings connected by a three carbon bridge; according to the degree of oxidation of the three carbon bridge, flavonoids are classified into different subgroups including anthocyanidins and flavonols.
fornix
(fōr′niks; pl., fornices, -nisēz) Arch-shaped structure. // A bundle of axons that originates in the hippocampal formation, loops around the thalamus, and terminates in the diencephalon.
gamma (γ) ray emission
The form of radioactive decay that occurs when an unstable nucleus emits extremely high frequency electromagnetic radiation.
genetic engineering
The manipulation of an organism’s genome by inserting or deleting DNA. // Any process by which genetic material, particularly DNA, is altered by a molecular biologist.
Glycemic index
A measure for the extent to which a food raises the blood glucose level. // The glycemic response of a food relative to a standard carbohydrate-containing food.
gonad
(gō′nad) Organ that produces sex cells and sex hormones; the ovaries in a female and the testes in a male. // A sexual organ (that is, ovary or testis) that produces gametes.
ground state
The lowest energy state in an atom, ion, or molecule. // The normal, stable form of an atom or molecule; as distinct from the excited state.
hemagglutination
The clumping of red blood cells. // The linking of multiple red blood cells by virus particles, resulting in a lattice; basis of a method to measure virus concentration. (Chapter 2)
hertz (Hz)
The unit of sound frequency equivalent to cycles per second. // A unit of measure of electromagnetic frequency, the number of waves that pass by a ixed point per second.
Hund’s rule
The principle stating that when electrons fill degenerate orbitals, they first fill them singly with parallel spins. // If two or more empty orbitals of equal energy are available, one electron occupies each, with their spins parallel, until all are half-full.
Hydroxyl radical
An extremely reactive and highly toxic byproduct of oxidative metabolism. // A toxic form of oxygen (OH•) formed in cytoplasm by ionizing radiation and aerobic respiration.
hypothalamus
The ventral part of the diencephalon, involved in the control of the autonomic nervous system and the pituitary gland. // (hı̄′pō-thal′ă-mŭs) Region of the brain in the diencephalon; regulates body temperature, autonomic nervous system, and endocrine system.
immunology
The study of a host’s defenses to a pathogen. // The study of all aspects of host defense against infection and also of the adverse consequences of immune responses.
Indel
Insertions and deletions. // A mutation consisting of either an insertion or a deletion of DNA sequences.
initiator caspases
Proteases that promote apoptosis by cleaving and activating other caspases. // Apoptotic caspases that begin the apoptotic process, activating the executioner caspases. initiator tRNA Special tRNA that intiates translation. It always carries the amino acid methionine, forming the complex MettRNAi.
Intercalation
Planar and lipophilic compounds can intercalate between base stacks of DNA; this leads to frame shift mutations (leading to inactive proteins). // Insertion between stacked aromatic or planar rings; for example, the insertion of a planar molecule between two successive bases in a nucleic acid.
isozyme
An enzyme that has more than one form. // Multiple forms of an enzyme that catalyze the same reaction but differ in amino acid sequence, substrate affinity, Vmax, and/or regulatory properties; also called isoenzymes.
Kupffer cells
Macrophages of the liver that are part of the reticuloendothelial system. // Phagocytes lining the hepatic sinusoids; they remove debris and dying cells from the blood, but are not known to elicit immune responses.
Leaving group
The group that is replaced in a substitution reaction. // The departing or displaced molecular group in a unimolecular elimination or bimolecular substitution reaction.
Lewy bodies
Intracellular inclusions of insoluble proteins in neurons, found in some neurodegenerative diseases.
long noncoding RNA (lncRNA)
A long RNA molecule that does not encode a polypeptide. // One of a large group (≈8000 in humans) of RNAs longer than 200 nucleotides and not coding for protein. The functions, if any, of most lncRNAs is unknown but individual lncRNA are known to play important roles in the cell, for example, in telomerase function and genomic imprinting. In a general sense, lncRNAs are believed to act as scaffolds, holding together proteins and nucleic acids to speed up a wide variety of reactions in the cell.
magnetic resonance imaging (MRI)
A medical diagnostic technique based on nuclear magnetic resonance. // Method for determining tissue density by using a large electromagnet that creates a magnetic field. After radio waves are introduced, the magnetic field realigns hydrogen atoms that give off their excess energy at different rates depending on the type of tissue. Emitted energy is then analyzed by a computer, which constructs an image.
metabolon
A supramolecular assembly of sequential metabolic enzymes. // Array of enzymes closely associated in a specific cellular compartment discussed as a plausible platform for the biosynthesis of various specialized metabolites.
micro RNA (miRNA)
A type of small RNA that inhibits mRNA translation. // A type of RNA composed of a few nucleotide base pairs that are encoded by genomic DNA. miRNA blocks translation by binding to the complementary sequences of mRNA. Also enhances mRNA degradation.
molarity (M)
(mō-lar′i-tē) Number of moles in 1 liter of solution. // A means of expressing solution concentration as the number of moles of solute per liter of solution.
multi-drug-resistant (MDR)
M. tuberculosis strains resistant to isoniazid and rifampin.
myeloid // myeloid cell
Any white blood cell other than a lymphocyte. // Refers to the lineage of blood cells that includes all leukocytes except lymphocytes.
neural crest
The primitive embryonic peripheral nervous system, consisting of neural ectoderm that pinches off laterally as the neural tube forms. // Collection of cells located along the line where the neural tube pinches off from the surrounding epidermis in the vertebrate embryo. Neural crest cells migrate to give rise to a variety of tissues, including neurons and glia of the peripheral nervous system, pigment cells of the skin, and the bones of the face and jaws.
Nitrogen balance
The difference between ingested nitrogen and excreted nitrogen. // The amount of nitrogen exiting a body compared with the amount entering.
nonionizing radiation
Short-wavelength radiation that does not cause ionization; ultraviolet (UV) radiation is an example. // The portion of the electromagnetic spectrum that does not lead to the production of positive and negative charges (ion pairs) in molecules. Visible and ultraviolet light are examples of nonionizing radiation (cf. Ionizing radiation).
octet rule
Tendency of atoms to maintain an outer shell with eight electrons. // The tendency for most bonded atoms to possess or share eight electrons in their outer shell to obtain stable electron configurations and lower their potential energy.
Orbital
A wave function, which describes the volume of space around a nucleus in which an electron is most likely to be found. // A probability distribution map, based on the quantummechanical model of the atom, used to describe the likely position of an electron in an atom; also, an allowed energy state for an electron.
ossicle
(os′i-kl) Small bone within the middle ear. // One of three small bones in the middle ear.
paracrine
Describes a cytokine or other biologically active molecule acting on cells near to those that produce it. // (par′a-krı̆n) Hormonal secretions that stimulate neighboring cells; also called a local hormone (does not enter the blood). Compare to endocrine.
Pauli exclusion principle
The principle that no two electrons in an atom can have the same four numbers. // No more than two electrons can occupy the same orbital, and those two must have spins of opposite sign.
peroxidase
Enzymes that consume hydrogen peroxide or organic peroxides. // An enzyme that destroys hydrogen peroxide: H2O2 + 2H+ → 2H2O
phosphoglyceride
Lipids structurally related to phosphatidic acid. // Phospholipid derived from glycerol, abundant in biomembranes.
phylogeny
The evolutionary history of a group of organisms; phylogenetic relationships are evolutionary relationships. // A diagram showing the evolutionary relationships among a group of organisms; an evolutionary tree.
plastid
In plants, a self-replicating organelle; may differentiate into a chloroplast or amyloplast. // A cytoplasmic body found in the cells of plants and some protozoa. Chloroplasts, for example, produce chlorophyll that is involved in photosynthesis.
polyribosome
A collection of several ribosomes floating freely in the cytoplasm. // mRNA engaged with multiple ribosomes in the act of translation.
posttranscriptional processing
The enzymatic processing of the primary RNA transcript to produce functional RNAs, including mRNAs, tRNAs, rRNAs, and many other classes of RNAs. // Chemical modification of RNA.
Prokaryotic cells
The cells of organisms classified as prokaryotes. These cells are characterized by not having a membrane-bound nucleus that contains the chromosomal DNA.
pyridoxal phosphate (PLP)
The coenzyme form of vitamin B6, used as prosthetic group in many enzymes of amino acid metabolism. // A coenzyme containing the vitamin pyridoxine (vitamin B6); functions in reactions involving amino group transfer.
reaction intermediate
Any chemical species in a reaction pathway that has a finite chemical lifetime. // A species that forms in one step of a reaction mechanism and is consumed in another.
reducing agent (reductant)
A substance that causes the reduction of another substance; a reducing agent loses electrons and is oxidized. // The electron donor in an oxidation-reduction reaction.
replica plating
A method of inoculating a number of solid minimal culture media from an original plate to produce the same pattern of colonies on each plate. // A procedure for duplicating the bacterial colonies growing on agar medium in one petri plate to agar medium in another petri plate.
Respiration (cellular)
Process by which cells produce energy by the oxidation of organic substances subdivided by the nature of terminal electron acceptor, e.g., aerobic, nitrate, iron, sulfate respiration.
reverse cholesterol transport
The removal of cholesterol from peripheral body tissues and transport to the liver for breakdown. The process normally uses highdensity lipoproteins. // The transport of cholesterol from extrahepatic tissues to the liver.
saponin
A class of chemical compounds referred to as glucosides that are present in many plants. Health benefits are thought to include cholesterol reduction, reduced cancer risk, immune system enhancement, prevention of bone loss, and antioxidant activity. // Glycosides of triterpenes and steroids; the aglycone is usually lipophilic whereas the saponins are amphiphilic with detergent properties; distinguished are monodesmosidic saponins with 1 sugar chain and bidesmosidic saponins with 2 sugar chains.
scurvy
A disease characterized by bleeding gums and pinpoint skin bleeding due to a vitamin C deficiency that causes defective collagen to form. // Disease caused by vitamin C deficiency, with impaired collagen synthesis and connective tissue abnormalities.
sensitization
The acute adaptive immune response made by susceptible individuals on first exposure to an allergen. In some of these individuals, subsequent exposure to the allergen will provoke an allergic reaction. // A type of nonassociative learning leading to an intensified response to all stimuli.
siderophore
Bacterial iron-binding proteins. // Fe(III)-complexing compounds synthesized by many organisms to capture Fe(III).
sinusoid
(sı̄′nŭ-soyd) Resembling a sinus; extremely permeable capillary in certain organs, such as the liver or the spleen. // Small blood vessels characterized by a discontinuous basal lamina, with no signifi cant barrier between the blood plasma and the membranes of surrounding cells. (Chapter 2)
specialized transduction
The process of transferring a piece of cell DNA adjacent to a prophage to another cell. // Recombination in bacteria mediated by a bacteriophage that can only transfer genes in a small segment of the chromosome of the donor cell to a recipient cell (cf. Generalized transduction).
Spike proteins
Viral proteins associated with the viral envelope.
sterol
A class of organic compound classified as a lipid. The biochemical structures are composed of four rings; an example is cholesterol. // A lipid containing the steroid nucleus.
superantigen
An antigen that activates many different T cells, thereby eliciting a large immune response. // Extremely powerful membrane bound T cell proteins that nonspecifi cally activate many subsets of T cells. (Chapter 5)
t-SNAREs
Protein receptors in a targeted membrane (typically the plasma membrane) that bind to v-SNAREs in the membrane of a secretory vesicle and mediate fusion of the vesicle and target membranes. // Transmembrane SNARE protein, usually composed of three proteins and found on target membranes where it interacts with v-SNAREs on vesicle membranes. tubulin The protein subunit of microtubules.
Termination signal
In transcription, a nucleotide sequence that specifies RNA chain termination.
TH17 cell
A type of effector helper T cell that secretes IL17, which recruits neutrophils and stimulates an inflammatory response.
Ti plasmid
The large plasmid in Agrobacterium tumefaciens. It is responsible for the induction of tumors in plants with crown gall disease and is an important vector for transferring genes into plants, especially dicots. // A tumor-inducing plasmid that can be incorporated into a host plant chromosome; found in Agrobacterium.
transaminase
Enzyme that transfers amine groups from amino acids to a-keto acids, such as pyruvate and a-ketoglutarate. // Enzymes catalyzing the reversible, vitamin B6–dependent transfer of an amino group from an amino acid to an α-keto acid.
Translocation
(1) Movement of the ribosome along the messenger RNA. (2) Transfer of DNA from one chromosome to another. // Change in position of a segment of a chromosome to another part of the same chromosome or to a different chromosome.
tumor
Mass of new tissue cells resulting from abnormal cell division. // A mass of cells originating from abnormal growth. (Chapter 6)
urea cycle
A cyclic metabolic pathway in vertebrate liver, synthesizing urea from amino groups and carbon dioxide. // A series of biochemical reactions by which ammonia is converted to urea for excretion. The process occurs mainly in the liver, with some activity in the kidney. urinary water The water that composes urine.
van der Waals forces
Intermolecular forces that are responsible for holding molecules together in the liquid and solid states. // Nonspecific attractive and repulsive forces between molecules.
Vitamin B2
Synonym for riboflavin
Wernicke-Korsakoff syndrome // Wernicke-like syndrome
Encephalopathy and amnesia caused by thiamine deficiency in persons who abuse alcohol. // A brain disorder due to thiamin deficiency.
zoonosis
A disease that occurs primarily in wild and domestic animals but can be transmitted to humans.
