BIO - TERMS - FREQUENCY > 2 PT 2 Flashcards
activator // activator (of gene expression) // Ac
(1) A DNA-binding protein that positively regulates the expression of one or more genes; that is, transcription rates increase when an activator is bound to the DNA. (2) A positive modulator of an allosteric enzyme. // A transposable element in maize that encodes a transacting transposase capable of catalyzing the movement of Ac elements and other members of the Ac/Ds family. // Regulator gene products that turn on, or activate, the expression of other genes.
adaptation
(1) Adaptation (desensitization): adjustment of sensitivity following repeated stimulation. The mechanism that allows a cell to react to small changes in stimuli even against a high background level of stimulation. (2) Evolutionary adaptation: an evolved trait. // (ad-ap-tā′shŭn) Advantageous change of an organ or tissue to meet new conditions. // Adjustment of an organism or a population to an environment.
adipocyte
An animal cell specialized for the storage of fats (triacylglycerols). // (ad′i-pō-sı̄t) Fat storage cell. // Another name for a fat cell that composes adipose tissue.
aerobe
An organism that lives in air and uses oxygen as the terminal electron acceptor in respiration. // An organism requiring molecular oxygen (O2) for growth. // Organisms that use oxygen as terminal electron acceptor.
Akt // Protein kinase B
Serine/threonine kinase activated downstream of PI3 kinase with numerous downstream targets involved in cell growth and survival, including activation of the mTOR pathways. // Serine/threonine protein kinase that acts in the PI-3- kinase/Akt intracellular signaling pathway involved especially in signaling cells to grow and survive. Also called protein kinase B (PKB). // A protein kinase that mediates effects of growth factors and insulin.
alcohol
A member of the family of organic compounds that contain a hydroxyl functional group (¬OH). // An organic molecule with the functional group —OH. // A class of compounds with an -OH group bonded to a saturated, sp3-hybridized carbon, ROH.
alkaptonuria
A rare inborn error of tyrosine metabolism, with accumulation of homogentisate. // An inborn error of metabolism in which a tyrosine breakdown product, homogentisate, is unable to be converted to the next product, maleyl-acetoacetate, due to a defect in the enzyme homogentisate dioxygenase. Accumulation of homogentisate leads to problems with joints and connective tissue. // An inherited metabolic disorder. Alkaptonurics excrete excessive amounts of homogentisic acid (alkapton) in the urine.
allosteric protein
A protein (generally with multiple subunits) with multiple ligand-binding sites, such that ligand binding at one site affects ligand binding at another. // A protein that can adopt at least two distinct conformations, and for which the binding of a ligand at one site causes a conformational change that alters the activity of the protein at a second site; this allows one type of molecule in a cell to alter the fate of a molecule of another type, a feature widely exploited in enzyme regulation. // A protein that can exist in alternative conformations.
anaerobic
(an-ār-ō′bik) Without oxygen. // Occurring in the absence of air or oxygen. // Oxygen deficient.
anomers
Monosaccharides that differ only in the orientation of substituents around their carbonyl carbons. // Two stereoisomers of a given sugar that differ only in the configuration about the carbonyl (anomeric) carbon atom. // Cyclic stereoisomers of sugars that differ only in their coniguration at the hemiacetal (anomeric) carbon.
antibody-dependent cell-mediated cytotoxicity (ADCC)
Th e process in which binding of an anti-viral IgG antibody to Fc receptors on macrophages and some NK cells targets these cells to kill infected cells that carry on their surfaces the antigen recognized by the antibody; also known as ADCC. (Chapter 4) // The killing of antibody-coated cells by natural killer cells and leukocytes. // The killing of antibody-coated target cells by cells with Fc receptors that recognize the constant region of the bound antibody. Most ADCC is mediated by NK cells that have the Fc receptor FcγRIII on their surface.
antigenic determinant
A specific region on the surface of an antigen against which antibodies are formed; also called epitope. // Specific region of an antigen that binds to an antibody or a complementary receptor on the surface of a B cell (BCR) or T cell (TCR). // That portion of an antigenic molecule that is bound by the antigen-binding site of a given antibody or antigen receptor; it is also known as an epitope.
archaea // archaeon (plural arch[a]ea) (archaebacterium)
One of the five kingdoms of living organisms; includes many species that thrive in extreme environments of high ionic strength, high temperature, or low pH. // Domain of prokaryotic cells lacking peptidoglycan; one of the three domains. // Singlecelled organism without a nucleus, superficially similar to bacteria. At a molecular level, more closely related to eukaryotes in genetic machinery than are bacteria. Archaea and bacteria together make up the prokaryotes.
atomic mass (atomic weight)
The total number of protons and neutrons in the nucleus of an atom. // The weighted average mass of an element’s naturally occurring isotopes. // The average mass in amu of the atoms of a particular element based on the relative abundance of the various isotopes; numerically equivalent to the mass in grams of 1 mol of the element.
base pair
Two nucleotides in an RNA or DNA molecule that are held together by hydrogen bonds—for example, G paired with C, and A paired with T or U. // Two nucleotides in nucleic acid chains that are paired by hydrogen bonding of their bases; for example, A with T or U, and G with C. // The arrangement of nitrogenous bases in nucleic acids based on hydrogen bonding; in DNA, base pairs are A-T and G-C; in RNA, base pairs are A-U and G-C.
basophil
(bā′sō-fil) The least common of the white blood cells. Basophils release proinflammatory agents; e.g., histamine, heparin. // A granulocyte (leukocyte) that readily takes up basic dye and is not phagocytic; has receptors for IgE Fc regions. // Type of white blood cell containing granules that stain with basic dyes. It is thought to have a function similar to mast cells.
blood-brain barrier
Structure formed by capillary endothelial cells and astrocytes that regulates what can enter the interstitial fluid in the brain: helps prevent transport of harmful substances from the blood into the brain. // Cell membranes that allow some substances to pass from the blood to the brain but restrict others. // A specialization of the walls of brain capillaries that limits the movement of bloodborne substances into the extracellular fl uid of the brain.
cadherin // cadherin superfamily
Member of the large cadherin superfamily of transmembrane adhesion proteins. Mediates homophilic Ca2+-dependent cell–cell adhesion in animal tissues. // Family of classical and nonclassical cadherin proteins with more than 180 members in humans. // Membrane-spanning cell adhesion proteins in the zonula adherens.
Calvin cycle // Calvin-Benson cycle
The cyclic pathway in plants that fixes carbon dioxide and produces triose phosphates. // A series of light-independent enzymatic reactions in the stroma of chloroplasts converting CO2 and water into organic compounds using ATP and NADPH from the photosynthetic light reactions.The key enzyme for carbon fixation in this cycle is Rubisco. // The fixation of CO2 into reduced organic compounds; used by autotrophs.
carcinogen
An agent capable of inducing cancer in an organism. // Any cancer-causing substance. // A substance that may cause cancer.
cardiolipin
A lipid found in many bacteria and in the inner mitochondrial membrane that is a ligand recognized by some human γ:δ T cells. // A membrane phospholipid in which two phosphatidic acid moieties share a single glycerol head group. // A phosphoglyceride in the inner mitochondrial membrane.
cDNA library
A collection of cloned DNA fragments derived entirely from the complement of mRNA being expressed in a particular organism or cell type under a defined set of conditions. // A collection of cDNA clones containing copies of the RNAs isolated from an organism or a specific tissue or cell type of an organism. // Collection of cloned DNA molecules representing complementary DNA copies of the mRNA produced by a cell.
cell-mediated immune response // cell-mediated immunity // cell-mediated response
An adaptive immune response in which antigen-specific effector T cells have the main role. The immunity to infection conferred by such a response is called cell-mediated immunity. A primary cell-mediated immune response is the T-cell response that occurs the first time a particular antigen is encountered. // Immune response involving T-lymphocytes. // Th e arm of the adaptive immune response consisting of helper and eff ector T lymphocytes. (Chapter 4) // 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.
central nervous system (CNS)
Composed of the brain and spinal cord. // The brain (including the retinas) and spinal cord. See also peripheral nervous system. // The brain and the spinal cord. See also peripheral nervous system.
chemical reaction
A process by which one or more substances convert to one or more different substances; see also chemical change. // Process during which chemical bonds of a molecule are broken and new ones are formed. // The process of making or breaking bonds between atoms.
chondroitin sulfate
One of a family of sulfated glycosaminoglycans, a major component of the extracellular matrix. // Glycosaminoglycan found in joint connective tissue, such as cartilage. // The most abundant glycosaminoglycan (GAG) in many connective tissues.
chylomicron
A plasma lipoprotein consisting of a large droplet of triacylglycerols stabilized by a coat of protein and phospholipid; carries lipids from the intestine to the tissues. // A structure composed of both lipids and proteins (a lipoprotein) that is produced within the epithelial cells lining the small intestine; serves in the absorption of lipids into the lymphatic capillaries. // Lipoproteins that carry dietary lipids from the intestine to other tissues.
clade
A group of organisms that share a particular common ancestor; a branch on a cladogram. // Taxa that share common ancestry fall in a clade. // Subtypes of human immunodefi ciency virus that are prevalent in diff erent geographic areas. (Chapter 7)
Clustered regularly interspersed palindromic repeats (CRISPR)
A defense mechanism in bacteria using small noncoding RNA molecules (crRNAs) to seek out and destroy invading viral genomes through complementary base-pairing and targeted nuclease digestion. // A strand of DNA with short repeats of DNA called “spacers” that is used as a gene editing tool. // An array of repeat sequences in the genomes of many bacteria and archaea that is involved in protecting these organisms from infection by bacteriophages. These repeats are separated from one another by spacers complementary to sequences in bacteriophage genomes.
coenzyme A (CoA)
A coenzyme that functions in decarboxylation. // A pantothenic acid–containing coenzyme that serves as an acyl group carrier in certain enzymatic reactions. // A cosubstrate that forms energy-rich thioester bonds with many organic acids.
complement
(kom′plĕ-ment) Group of plasma proteins working together during an innate immune response; these proteins complement or work along with antibodies. // A general term referring to all the components of the complement system. (Chapter 3) // A group of serum proteins involved in phagocytosis and lysis of bacteria.
complementary
Having a molecular surface with chemical groups arranged to interact specifically with chemical groups on another molecule. // (1) Of nucleic acid sequences: capable of forming a perfect base-paired duplex with each other. (2) Of other interacting molecules, such as an enzyme and its substrate: having biochemical or structural features that marry up, so that noncovalent bonding is facilitated. // Capable of precise pairing; in particular, the bases of nucleic acids.
cone photoreceptor (cone)
Cone-shaped cell in the retina that provides color vision; functions best in bright light. // A photoreceptor in the retina containing one of three photopigments that are maximally sensitive to different wavelengths of light. Cones are concentrated in the fovea, specialized for daytime vision, and responsible for all color vision. See also rod photoreceptor. // Photoreceptor cell in the vertebrate retina that is responsible for color vision in bright light.
congenital
(kon-jen′i-tăl) Present at birth. // Present at birth. The opposite of congenital is acquired. // Refers to a condition existing at birth; may be inherited or acquired in utero.
contact inhibition
The cessation of animal cell movement and division as a result of contact with other cells. // Inhibition of cell proliferation by contact with neighboring cells. // Cessation of cell division when cells make physical contact, as occurs at high density in a culture dish. (Chapter 6)
corticosteroid
(kōr-ti-kō-stēr′- oyd) Hormones secreted by the adrenal cortex; e.g., cortisol. // Family of drugs related to natural steroids such as cortisone. Corticosteroids can kill lymphocytes, especially developing thymocytes, inducing apoptotic cell death. They are medically useful antiinflammatory and immunosuppressive agents. // Glucocorticoids and mineralocorticoids; C-21 steroids that are derived from progestins by hydroxylation reactions.
coupled reaction
Linked pair of chemical reactions in which the free energy released by one serves to drive the other. // Two chemical reactions that have a common intermediate and thus a means of energy transfer from one to the other. // Two reactions that share a common intermediate so that the energy released in the favorable step allows the unfavorable step to occur.
Crohn disease
A type of inflammatory bowel disease. // Chronic inflammation of the bowel, particularly the ileum of the small intestine. // Chronic inflammatory bowel disease thought to result from an abnormal overresponsiveness to the commensal gut microbiota.
cyclic guanosine monophosphate (cGMP)
Nucleotide that is generated from GTP by guanylyl cyclase in response to various extracellular signals. // A second messenger formed from guanosine triphosphate by the action of the enzyme guanylyl cyclase. // Another second messenger in many cells.
Cystic fibrosis (CF)
A genetic disease caused by malfunction of a chloride channel in secretory epithelia. // Disease caused by defect in CFTR gene, leading to abnormally thick mucus and causing serious recurrent infections of the lung. // An autosomal recessive disorder in humans characterized by clogging of the lungs, pancreas, and liver with mucus and, as a result, chronic infections. The average life expectancy of an individual with cystic fibrosis is about 35 years.
cytotoxic T (TC) lymphocyte // cytotoxic T cell (TC cell)
(sı̄′tō-tok′-sik lı̄m′fō′sı̄t) A class of T-lymphocytes that release chemicals to destroy unhealthy cells; also called CD8 cells. // Type of T cell responsible for killing host cells infected with a virus or another type of intracellular pathogen. // T cells that can kill other cells, typically CD8 T cells defending against intracellular pathogens that live or reproduce in the cytosol, but in some cases also CD4 T cells.
dendrite
(den′drı̄t) Process on a neuron where graded potentials are initiated. // A neurite specialized to receive synaptic inputs from other neurons. // Extension of a nerve cell, often elaborately branched, that receives stimuli from other nerve cells. dendritic cell The most potent type of antigen-presenting cell, which takes up antigen and processes it for presentation to T cells. It is required for activating naive T cells.
depolarization
(dē-pō′lăr-i-zā- shŭn) Change in membrane potential or voltage to a more positive value. // A change in membrane potential, taking it from the value at rest (e.g., –65 mV) to a less negative value (e.g., 0 mV). // Deviation in the electric potential across the plasma membrane towards a positive value. A depolarized cell has a potential that is positive outside and negative inside.
diacylglycerol (DAG)
A lipid intracellular signaling molecule formed from membrane inositol phospholipids that are cleaved by the action of phospholipase C-γ after the activation of many different receptors. The diacylglycerol stays in the membrane and activates protein kinase C and RasGRP, which further propagate the signal. // Lipid produced by the cleavage of inositol phospholipids in response to extracellular signals. Composed of two fatty acid chains linked to glycerol, it serves as a small signaling molecule to help activate protein kinase C (PKC). // A second messenger molecule formed by the action of phospholipase C on the membrane phospholipid phosphatidylinositol-4, 5-bisphosphate. DAG activates the enzyme protein kinase C.
DNA microarray
“DNA chip” used for studies of gene expression or genetic variation. // A large array of short DNA molecules (each of known sequence) bound to a glass microscope slide or other suitable support. Used to monitor expression of thousands of genes simultaneously: mRNA isolated from test cells is converted to cDNA, which in turn is hybridized to the microarray. // A collection of DNA sequences immobilized on a solid surface, with individual sequences laid out in patterned arrays that can be probed by hybridization.
eicosanoid
A lipid derived biologically from 5,8,11,14-eicosatetraenoic acid, or arachidonic acid. Prostaglandins, thromboxanes, and leukotrienes are examples. // A powerful biochemical produced by longchain fatty acids that has profound effects on physiology. electrolyte A compound that ionizes when dissolved in water. // (ı̄′kō′-să-noydz) Local hormones derived from fatty acids.
electron
A negatively charged particle in motion around the nucleus of an atom. // A negatively charged, low-mass particle found outside the nucleus of all atoms that occupies most of the atom’s volume but contributes almost none of its mass. // Subatomic particle with a negative charge; found orbiting the nucleus of an atom.
Elongation // Elongation (of DNA, RNA, or protein synthesis)
Stepwise incorporation of ribonucleoside monophosphates or deoxyribonucleoside monophosphates into the 3 -OH end of the growing RNA or DNA chain in the 5’ → 3’ direction. (Chapter 6) // The addition of carbons, usually two for each reaction, in the synthesis of fatty acids. // The incorporation of the second and subsequent subunits (nucleotides or amino acids) during the synthesis of a macromolecule (DNA, RNA, or polypeptide).
endocrine
(en′dō-krin) Hormonal secretions that are transported by the blood. Compare to exocrine. // Pertaining to cellular secretions that enter the bloodstream and have their effects on distant tissues. // Describes the action of a biologically active molecule such as a hormone or cytokine that is secreted by one tissue into the blood and acts on a distant tissue. Cf. autocrine, paracrine.
endothermic // endothermic reaction
A reaction that absorbs heat and therefore has a positive enthalpy change. // A chemical reaction that takes up heat (that is, for which DH is positive). // A chemical reaction that absorbs heat from its surroundings; for an endothermic reaction, ΔH > 0.
envelope
An outer covering surrounding the capsid of some viruses. // The host cell-derived lipid bilayer carrying viral glycoproteins that forms the outer layer of many virus particles. (Chapter 4) // A membrane, acquired from the host cell, that surrounds many animal viruses.
epimers
Two stereoisomers differing in configuration at one asymmetric center in a compound having two or more asymmetric centers. // Diastereomers that differ in coniguration at only one chirality center but are the same at all others. // Monosaccharides differing in the configuration of substituents around one asymmetric carbon.
equilibrium
State in a chemical reaction where there is no net change in free energy to drive the reaction in either direction. The ratio of product to substrate reaches a constant value at chemical equilibrium. // The state of a system in which no further net change is occurring; the free energy is at a minimum. // A state of dynamical systems in which there is no net change.
Exothermic // exothermic reaction
A chemical reaction that releases heat (that is, for which DH is negative). // A reaction that releases heat and therefore has a negative enthalpy change. // A chemical reaction that releases heat to its surroundings; for an exothermic reaction, ΔH < 0.
F factor (fertility factor)
A bacterial episome that confers the ability to function as a genetic donor (“male”) in conjugation; the fertility factor in bacteria. // A self-transmissible plasmid in Escherichia coli. // A plasmid found in the donor cell in bacterial conjugation.
fermentation
The enzymatic degradation of carbohydrates in which the final electron acceptor is an organic molecule, ATP is synthesized by substrate-level phosphorylation, and O2 is not required. // Anaerobic energy-yielding metabolic pathway involving the oxidation of organic molecules. Anaerobic glycolysis refers to the process whereby pyruvate is converted into lactate or ethanol, with the conversion of NADH to NAD+. // Energy-yielding anaerobic breakdown of a nutrient molecule, such as glucose, without net oxidation; yields lactate, ethanol, or some other simple product.
fibrin
(fı̄′brin) The supporting meshwork of insoluble fibrous protein within a blood clot. // A fibrous protein that serves as the foundational network of a blood clot. // A protein factor that forms the crosslinked fibers in blood clots.
fibroblast
(fı̄′brō-blast) Large, flat, connective tissue cells with tapered ends that produce the fibers and ground substance components of the extracellular matrix of connective tissue. // A cell of the connective tissue that secretes connective tissue proteins such as collagen. // Common cell type found in connective tissue. Secretes an extracellular matrix rich in collagen and other extracellular matrix macromolecules. Migrates and proliferates readily in wounded tissue and in tissue culture.
flavoprotein
An enzyme containing a flavin nucleotide as a tightly bound prosthetic group. // A protein containing the coenzyme flavin; functions as an electron carrier in electron transport chains. // Proteins containing a flavin coenzyme (either flavin mononucleotide [FMN] or flavin adenine dinucleotide [FAD]) as a prosthetic group; participate in hydrogen transfer reactions.
fluorescence
Emission of light by excited molecules as they revert to the ground state. // The ability of a substance to give off light of one color when exposed to light of another color. // Emission of light after excitation with light or electromagnetic irradiation; the emitted light has always a lower energy (longer wavelength) than the absorbed light/radiation.
Frequency, ν
The number of sound waves or other discrete events per second, expressed in hertz (Hz). // For waves, the number of cycles (or complete wavelengths) that pass through a stationary point in one second. // The number of electromagnetic wave cycles that travel past a ixed point in a given unit of time. Frequencies are expressed in units of cycles per second, or hertz.
fusion protein
(1) One of a family of proteins that facilitate membrane fusion. (2) The protein product of a gene created by the fusion of two distinct genes or portions of genes. // A polypeptide made from a recombinant gene that contains portions of two or more different genes. The different genes are joined so that their coding sequences are in the same reading frame. // Engineered protein that combines two or more normally separate polypeptides. Produced from a recombinant gene.
ganglioside
Sphingolipid containing a complex oligosaccharide as a head group; especially common in nervous tissue. // Any glycolipid having one or more sialic acid residues in its structure. Found in the plasma membrane of eukaryotic cells and especially abundant in nerve cells. // Sphingolipids containing an acidic oligosaccharide.
gene expression
Transcription, and in the case of proteins, translation, to yield the product of a gene; a gene is expressed when its biological product is present and active. // The process of transcribing the information from a gene into messenger RNA; a gene is a segment of DNA carrying the instructions for a single protein. // The process by which genes produce RNAs and proteins and exert their effects on the phenotype of an organism.
genetics
The science of heredity and gene function. // The study of the genes of an organism on the basis of heredity and variation. // The science of heredity and variation.
glial cell
Supporting non-neural cell of the nervous system. Includes oligodendrocytes and astrocytes in the vertebrate central nervous system and Schwann cells in the peripheral nervous system. // A support cell in the nervous system. Glia are classified into four categories: astrocytes, oligodendroglia, Schwann cells, and microglia. Astrocytes regulate the extracellular environment of the brain, oligodendroglia and Schwann cells provide myelin, and microglia scavenge debris. // Nervous system cells that support neurons.
glucogenic
Capable of being converted into glucose or glycogen by the process of gluconeogenesis. // Glucose forming. // Normally refers to the production of glucose with the breakdown of certain amino acids.
Glutathione (γ-Glu-Cys-Gly)
A tripeptide of glutamic acid, cysteine, and glycine involved in antioxidant activities. // A tripeptide with reducing properties. // Enzymatically synthesized sulphur- containing tripeptide.
