BIO - TERMS - FREQUENCY > 2 PT 2 Flashcards
(171 cards)
1
Q
activator // activator (of gene expression) // Ac
A
(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.
2
Q
adaptation
A
(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.
3
Q
adipocyte
A
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.
4
Q
aerobe
A
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.
5
Q
Akt // Protein kinase B
A
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.
6
Q
alcohol
A
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.
7
Q
alkaptonuria
A
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.
8
Q
allosteric protein
A
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.
9
Q
anaerobic
A
(an-ār-ō′bik) Without oxygen. // Occurring in the absence of air or oxygen. // Oxygen deficient.
10
Q
anomers
A
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.
11
Q
antibody-dependent cell-mediated cytotoxicity (ADCC)
A
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.
12
Q
antigenic determinant
A
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.
13
Q
archaea // archaeon (plural arch[a]ea) (archaebacterium)
A
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.
14
Q
atomic mass (atomic weight)
A
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.
15
Q
base pair
A
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.
16
Q
basophil
A
(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.
17
Q
blood-brain barrier
A
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.
18
Q
cadherin // cadherin superfamily
A
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.
19
Q
Calvin cycle // Calvin-Benson cycle
A
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.
20
Q
carcinogen
A
An agent capable of inducing cancer in an organism. // Any cancer-causing substance. // A substance that may cause cancer.
21
Q
cardiolipin
A
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.
22
Q
cDNA library
A
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.
23
Q
cell-mediated immune response // cell-mediated immunity // cell-mediated response
A
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.
24
Q
central nervous system (CNS)
A
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.
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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.
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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.
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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.
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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)
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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.
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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.
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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.
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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.
33
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.
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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.
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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)
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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.
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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.
38
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.
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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.
40
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.
41
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.
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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.
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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.
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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.
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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.
46
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.
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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.
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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).
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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granulocyte
A leukocyte with visible granules in the cytoplasm when viewed through a light microscope; includes neutrophils, basophils, and eosinophils. // Category of white blood cell distinguished by conspicuous cytoplasmic granules. Includes neutrophils, basophils, and eosinophils. Arises from a granulocyte/ macrophage (GM) progenitor cell. // White blood cells with multilobed nuclei and cytoplasmic granules. They comprise the neutrophils, eosinophils, and basophils. Also known as polymorphonuclear leukocytes.
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growth hormone (GH)
An anabolic hormone that can enhance cellular amino acid uptake and stimulate protein synthesis; also known as somatotropin. // Mammalian hormone secreted by the pituitary gland into the bloodstream that stimulates growth throughout the body. // A signaling polypeptide required for normal growth in humans; it is deficient in individuals with certain types of dwarfism.
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guanine nucleotide exchange factor (GEF)
Protein that binds to a GTPase and activates it by stimulating it to release its tightly bound GDP, thereby allowing it to bind GTP in its place. // Proteins that can remove the bound GDP from G proteins, thus allowing GTP to bind and activate the G protein. // Regulatory proteins that bind to and activate G proteins by stimulating the exchange of bound GDP for GTP.
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hematocrit
(hē′mă-tō-krit, hem′ă-) Percentage of erythrocytes compared to total blood. // The percentage of blood that is composed of red blood cells. // The percentage of the blood volume that is occupied by blood cells.
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heterochromatin
Chromatin that is highly condensed even in interphase; generally transcriptionally inactive. (Compare with euchromatin.) // Chromatin staining darkly even during interphase, often containing repetitive DNA with few genes. // A condensed, transcriptionally inactive form of chromatin.
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heterozygous
(het′er-ō-zı̄′gŭs) Having both dominant and recessives alleles for a trait. // Describes individuals that have two different alleles of a given gene, one inherited from the mother and one from the father. // Carrying two different variants of a gene.
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histamine
(his′tă-mēn) Chemical that increases capillary permeability and causes vasodilation; released by basophils and mast cells. // A substance released by tissue cells that causes vasodilation, capillary permeability, and smooth muscle contraction. // A vasoactive amine stored in mast-cell granules. Histamine released by antigen binding to IgE antibodies bound to mast cells causes the dilation of local blood vessels and the contraction of smooth muscle, producing some of the symptoms of IgE-mediated allergic reactions. Antihistamines are drugs that counter histamine action.
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homeostasis
(hō′mē-ō-stā′sis, -os′tă-sis) A consistent internal environment in the body with respect to various functions and the chemical composition of fluids and tissues. // The balanced functioning of physiological processes and maintenance of an organism’s internal environment within a narrow range. // The maintenance of a dynamic steady state by regulatory mechanisms that compensate for changes in external circumstances.
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homologous recombination (general recombination)
Reciprocal exchange of DNA between two DNA molecules of related sequence. // The exchange of genetic information between any pair of related DNAs at sites with identical sequences. (Chapter 9) // Genetic exchange between a pair of identical or very similar DNA sequences, typically those located on two copies of the same chromosome. Also a DNA repair mechanism for doublestrand breaks.
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Horizontal gene transfer (HGT)
Gene transfer between bacteria via natural transformation by released naked DNA, transduction by bacteriophages, or sexual exchange by conjugation. // Transfer of genes between two organisms in the same generation. See also vertical gene transfer. // Transfer of genes or genomes between unrelated organisms.
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humoral immunity // humoral immune response // humoral response
Immunity produced by antibodies dissolved in body fluids, mediated by B cells; also called antibody-mediated immunity. // Immunity due to proteins circulating in the blood, such as antibodies (in adaptive immunity) or complement (in innate immunity). Adaptive humoral immunity can be transferred to unimmunized recipients by the transfer of serum containing specific antibody. // Th e arm of the adaptive immune response that produces antibodies. (Chapter 4)
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hydrophilic
Polar or charged; describes molecules or groups that associate with (dissolve easily in) water. // Dissolving readily in water. Literally, “water loving.” hydrophobic (lipophilic) Not dissolving readily in water. Literally, “water-fearing.” // Water-loving; attracted to water.
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hypertrophy
Increase in the size of cells in a tissue. // Increase in cell size. // Index indicating the systemic impact of a training session.
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IgD
Immunoglobulin class composed of δ heavy chains that appears as surface immunoglobulin on mature B cells. // Immunoglobulin D; produced by immature naïve B cells after leaving the bone marrow. Transmembrane IgD and IgM proteins, with the same antigen-binding site, form the B cell receptors (BCRs) on these cells. // The class of antibodies found on B cells.
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IgG
Immunoglobulin class composed of γ heavy chains that is the most abundant class of immunoglobulin in the plasma. // Immunoglobulin G; the major antibody class in the blood, produced in especially large quantities during secondary antibody responses. The tail region of some IgG subclasses can bind to specific Fc receptors on macrophages and neutrophils. Antigen–IgG complexes can activate complement. // The most abundant class of antibodies in serum.
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immunoglobulin (Ig)
An antibody protein generated against, and capable of binding specifically to, an antigen. // A protein (antibody) formed in response to an antigen and can react with that antigen. See also globulin.
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immunological synapse
The highly organized interface that develops between a T cell and an antigen-presenting cell (APC) or target cell it is in contact with, formed by T-cell receptors binding to antigen–MHC complexes on the APC and celladhesion proteins binding to their counterparts on the APCs. // A specialized, organized structure formed upon aggregation of the T cell receptors of a cytotoxic T cell bound to peptide presented by MHC on the target cells; this structure allow prolonged signaling from the engaged T cell receptors and associated co-receptors, and facilitates polarization of the T cell secretion machinery. (Chapter 4) // The highly organized interface that develops between a T cell and the target cell it is in contact with, formed by T-cell receptors binding to antigen and cell-adhesion molecules binding to their counterparts on the two cells. Also known as the supramolecular adhesion complex.
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induced pluripotent stem cells (iPS cells)
Stem cells with the potential to differentiate into any cell type, including neurons, that are chemically transformed from mature cells derived from a person. // Pluripotent stem cells that are derived from adult somatic cells by the introduction of a cocktail of transcription factors. // Cells that are induced by artificial expression of specific transcription regulators to look and behave like the pluripotent embryonic stem cells that are derived from embryos.
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interferon (IFN)
A specific group of cytokines. Alpha- and beta-IFNs are antiviral proteins produced by certain animal cells in response to a viral infection. Gamma-IFN stimulates macrophage activity. // Cytokines that activate antiviral programs. (Chapter 3) // Several related families of cytokines originally named for their interference of viral replication. IFN-α and IFN-β are antiviral in their effects; IFN-γ has other roles in the immune system.
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interphase
Long period of the cell cycle between one mitosis and the next. Includes G1 phase, S phase, and G2 phase. // First phase of the cell cycle during which the cell carries out normal activities and prepares for cell division. // The stage in the cell cycle when the cell is not dividing; the metabolic stage during which DNA replication occurs; the stage following telophase of one division and extending to the beginning of prophase in the next division.
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intrinsic pathway (mitochondrial pathway) // intrinsic pathway of apoptosis
Pathway of apoptosis in which cell death is induced in response to indicators of internal stress, such as DNA damage. (Chapter 3) // Pathway of apoptosis activated from inside the cell in response to stress or developmental signals; depends on the release into the cytosol of mitochondrial proteins normally resident in the mitochondrial intermembrane space. // Signaling pathway that mediates apoptosis in response to noxious stimuli including UV irradiation, chemotherapeutic drugs, starvation, or lack of the growth factors required for survival. It is initiated by mitochondrial damage. Also called the mitochondrial pathway of apoptosis.
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ischemia
(is-kē′mē-ă) Reduced blood flow; may lead to hypoxia. // Localized decreased blood flow. // Interruption of the blood supply.
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isoprenoid
Any of a large number of natural products synthesized by enzymatic polymerization of two or more isoprene units; also called terpenoid. // A class of chemical structures that function as pigments, vitamins, and precursors to sex hormones. Sometimes referred to as terpinoids. // Lipids synthesized from branched-chain five-carbon units.
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ketogenic
Refers to the production of ketone bodies with the breakdown of certain amino acids. // Yielding acetyl-CoA, a precursor for ketone body formation, as a breakdown product. // Ketone body forming.
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Koch’s postulates
Criteria developed by the German physician Robert Koch in the late 1800s to determine if a given agent is the cause of a specific disease. (Chapter 1) // Criteria used to determine the causative agent of infectious diseases. // Criteria developed by the German physician Robert Koch in the late 1800s to determine whether a given agent is the cause of a specifi c disease. (Chapter 1)
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Lewis model // Lewis electron-dot structures (Lewis structures)
A drawing that represents chemical bonds between atoms in molecules as shared or transferred electrons; the valence electrons of atoms are represented as dots in a Lewis structure. // A simple model of chemical bonding using diagrams that represent bonds between atoms as lines or pairs of dots. According to this model, atoms bond together to obtain stable octets (eight valence electrons). // Representations of molecules showing valence electrons as dots.
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lipid bilayer (phospholipid bilayer)
A double-layered structure made of phospholipids or glycolipids, in which the polar heads of the molecules interact with the environment and the nonpolar tails interact with each other; a component of many cellular membranes. // The ordered lipid structure that forms a cell membrane. // Thin double sheet of phospholipid molecules that forms the core structure of all cell membranes. The two layers of lipid molecules are packed with their hydrophobic tails pointing inward and their hydrophilic heads outward, exposed to water.
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low-density lipoprotein (LDL)
Large complex composed of a single protein molecule and many esterified cholesterol molecules, together with other lipids. The form in which cholesterol is transported in the blood and taken up into cells. (Figure 13–51) // A chemical structure, composed of both lipids and proteins, that transports the lipids within the blood. // The lipoprotein that delivers cholesterol to the cells.
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Lysogenic bacterium
Pertaining to a bacterium that carries the genetic information of a quiescent bacteriophage, which can be induced to reproduce, and subsequently lyse, the bacterium. (Chapter 1) // Those harboring temperate bacteriophages. // A bacterium that harbors a prophage.
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major histocompatibility complex (MHC)
A cluster of genes on human chromosome 6 that encodes a set of membrane glycoproteins called the MHC molecules. The MHC also encodes proteins involved in antigen processing and other aspects of host defense. The genes for the MHC molecules are the most polymorphic in the human genome, having large numbers of alleles at the various loci. // The genes that code for histocompatibility antigens; also known as human leukocyte antigen (HLA) complex. // Plasma membrane proteins used to mark cells as self and to present antigens.
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Mass spectrometry (MS)
An experimental method of determining the precise mass and relative abundance of isotopes in a given sample using an instrument called a mass spectrometer. // Separation of ions in a mass analyzer according to their mass-to-charge (m/z) ratio. A mass spectrometer is composed of a sample introduction system, an ion source, a mass analyzer, and a detector. Mass spectrometry is the key technique for modern proteomics. // A technique for measuring the mass, and therefore the molecular weight (MW), of ions.
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matrix
(mā′triks; pl., matrices, mā′tri-sēz) Surrounding substance within which cells or structures are contained or embedded. // Fluid in mitochondria. // The space enclosed by the inner membrane of the mitochondrion.
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mesoderm
(mez′ō-derm) The middle of the three primary germ layers of the embryo. // Embryonic tissue that is the precursor to muscle, connective tissue, skeleton, and many of the internal organs. // The middle germ layer that forms in the early animal embryo and gives rise to such parts as bone and connective tissue.
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metabolomics
The study of small molecules in and around growing cells. // Global identification and quantification of all metabolites in a biological system (cell fluid, tissue) including their time- and space-resolved distribution. // The systematic characterization of the metabolome of a cell or tissue.
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microbiome // microbiota
All the microorganisms in an environment. // The combined genomes of the various species of a defined microbiota. // The collective of microorganisms that reside in or on an organism.
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microglia // microglial cell
(mı̄-krog′lē-ă) Category of small glial cells in the central nervous system; wander and exhibit phagocytic activity. // A type of cell that functions as a phagocyte in the nervous system to remove debris left by dead or dying neurons and glia. // An embryonically derived form of tissue macrophage in the central nervous system that is dependent on IL-34 for local self-renewal throughout life.
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mitogen
Extracellular signal molecule that stimulates cells to proliferate. // Extracellular signaling molecules that induce cell proliferation. (Chapter 6) // Mitosis-inducing agent.
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mortality // mortality rate
The number of deaths from a specific notifiable disease. // Th e percentage of deaths in a specifi ed population of infected individuals. (Chapter 1) // The number of deaths resulting from a disease in a given period of time in relation to the total population.
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muscarinic receptor // muscarinic ACh receptor
A subtype of acetylcholine receptor that is G-protein-coupled. // A type of adrenergic receptor that binds muscarine. // G protein–linked receptors for acetylcholine. // A multinucleated skeletal muscle cell. // An alternative term for a muscle cell based on the thin, elongated appearance of muscle cells; the unit responsible for contraction.
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mutagen
An agent in the environment that brings about mutations. // An environmental agent, either physical or chemical, that is capable of inducing mutations. // Mutation-inducing agent.
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myoglobin
(mı̄-ō-glō′bin) Oxygen-carrying and -storing molecule in muscle. // A compound found in muscle that carries oxygen from the cell membrane to the mitochondria. // An oxygen-binding protein in muscle tissue.
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necrosis
The process of cell death that occurs in response to noxious stimuli, such as nutrient deprivation, physical injury, or infection. To be distinguished from apoptosis, in which the cell activates an internal, or intrinsic, program of death, such as occurs in immune cells as a result of deficiency of cell survival signals. // (nĕ-krō′sis) Pathologic death of cells or a portion of a tissue or organ. // Tissue death.
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neutron
(nū′tron) Subatomic particle with a neutral charge; found in the nucleus of an atom. // An electrically neutral subatomic particle found in the nucleus of an atom, with a mass almost equal to that of a proton. // An uncharged particle in the nucleus of an atom.
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Nuclease
An enzyme that catalyzes the degradation of nucleic acids. // Enzymes cleaving phosphodiester bonds in a nucleic acid. // Enzymes that hydrolyze the internucleotide (phosphodiester) linkages of nucleic acids.
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opsonization
The coating of the surface of a pathogen by antibody and/or complement that makes it more easily ingested by phagocytes. // The enhancement of phagocytosis by coating microorganisms with certain serum proteins (opsonins); also called immune adherence. // Stimulation of phagocytosis by an antibody or other protein bound to the surface of a particle.
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orthologs // orthologous genes
. Homologous genes present in different species (cf. Homologous genes). // Genes or proteins from different species that are similar in sequence because they are descendants of the same gene in the last common ancestor of those species. Compare paralogs. // Genes or proteins from different species that possess a clear sequence and functional relationship to each other.
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osteoclast
(os′tē-ō-klast) Large cell type that functions in the absorption and removal of bone connective tissue. // Bone cell responsible for bone breakdown. osteomalacia Loss of mineralization, resulting in decreased bone density. // Macrophage-like cell that erodes bone, enabling it to be remodeled during growth and in response to stresses throughout life.
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pathogen-associated molecular patterns (PAMPs)
Molecules or molecular features unique to pathogens. (Chapter 3) // Microbe-associated molecules, either not present or sequestered in the host organism, that often occur in repeating patterns that are recognized by pattern recognition receptors (PRRs) in or on cells of the innate immune system. PAMPs are present in various microbial molecules, including nucleic acids, lipids, polysaccharides, and proteins. // Molecules specifically associated with groups of pathogens that are recognized by cells of the innate immune system.
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pentose phosphate pathway
A metabolic pathway that can occur simultaneously with glycolysis to produce pentoses and NADH without ATP production; also called hexose monophosphate shunt. // A pathway present in most organisms that serves to interconvert hexoses and pentoses and is a source of reducing equivalents (NADPH) and pentoses for biosynthetic processes; it begins with glucose 6-phosphate and includes 6-phosphogluconate as an intermediate. Also called the phosphogluconate pathway and the hexose monophosphate pathway. // A biochemical pathway that generates both NADPH and pentose sugars. Sometimes called the hexose monophosphate shunt.
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peptidyl transferase
The enzyme activity that synthesizes the peptide bonds of proteins; a ribozyme, part of the rRNA of the large ribosomal subunit. // The enzymatic activity of the large ribosomal subunit that forms the peptide bond. // An enzyme activity—built into the large subunit of the ribosome—that catalyzes the formation of peptide
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phagosome
A food vacuole of a phagocyte; also called a phagocytic vesicle. // Intracellular vesicle formed when particulate material is ingested by a phagocyte. // Large intracellular membrane-enclosed vesicle that is formed as a result of phagocytosis. Contains ingested extracellular material.
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phospholipase C (PLC)
A type of enzyme that cleaves phosphoglycerides between glycerol and phosphate. // An enzyme that cleaves the membrane phospholipid phosphatidylinositol-4,5-bisphosphate to form the second messengers diacylglycerol (DAG) and inositol triphosphate (IP₃). // Membrane-bound enzyme that cleaves inositol phospholipids to produce IP3 and diacylglycerol in the inositol phospholipid signaling pathway. PLCβ is activated by GPCRs via specific G proteins, while PLCγ is activated by RTKs.
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plasma
(1) The liquid portion of blood in which the formed elements are suspended. (2) Excited gases used for sterilizing. // (plaz′mă) The liquid portion of blood. // The noncellular component of blood composed primarily of water with dissolved substances, such as proteins, glucose, electrolytes, and clotting factors.
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point mutation
Change in a single base pair. // Exchange of a single base pair in DNA. // Changes that occur at specific sites in genes. They include nucleotide-pair substitutions and the insertion or deletion of one or a few nucleotide pairs.
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positive selection
A process occurring in the thymus in which only those developing T cells whose receptors can recognize antigens presented by self MHC molecules can mature. // (re: T cells) Th e process in which only T cells with T cell receptors that can bind to MHC proteins are retained during T cell diff erentiation. (Chapter 4) // In immunology: process of thymocyte maturation in which thymocytes expressing a T cell receptor with appropriate affinity for a self peptide bound to a self MHC protein is signaled to survive and continue development. post-transcriptional controls Any control on gene expression that is exerted at a stage after transcription has begun.
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Primase
A specialized RNA polymerase that synthesizes a primer during DNA replication. // An enzyme that synthesizes RNA primers for DNA synthesis. (Chapter 9) // Enzymes that catalyze the formation of RNA oligonucleotides used as primers by DNA polymerases.
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prion
An infectious agent consisting of a self-replicating protein, with no detectable nucleic acids. // (prı̄′on) Small diseasecausing protein. // Infectious agents comprising an abnormal isoform of a normal cellular protein but no nucleic acid; implicated as the causative agents of transmissible spongiform encephalopathies. (Chapter 1)
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proofreading
The correction of errors in the synthesis of an information-containing biopolymer by removing incorrect monomeric subunits after they have been covalently added to the growing polymer. // Correction of mistakes made during chain elongation by exonuclease activities of DNA-dependent DNA polymerases. (Chapter 6) // The enzymatic scanning of DNA for structural defects such as mismatched base pairs.
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protein kinase C (PKC)
The diacylglycerol-activated protein kinase. // A protein kinase activated by the second messenger DAG. // Ca2+-dependent protein kinase that, when activated by diacylglycerol and an increase in the concentration of cytosolic Ca2+, phosphorylates target proteins on specific serine and threonine residues.
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purine
A nitrogenous heterocyclic base found in nucleotides and nucleic acids; contains fused pyrimidine and imidazole rings. // A double-ring nitrogen-containing base present in nucleic acids; adenine and guanine are the two purines present in most DNA and RNA molecules. // The class of nucleic acid bases that includes adenine and guanine.
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pyrimidine
A nitrogenous heterocyclic base found in nucleotides and nucleic acids. // A single-ring nitrogen-containing base present in nucleic acids; cytosine and thymine are commonly present in DNA, whereas uracil usually replaces thymine in RNA. // The class of nucleic acid bases that includes uracil, thymine, and cytosine.
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radioactive isotope // radioisotope
An unstable isotope (form of an atom) that emits ionizing radiation. // An isotopic form of an element with an unstable nucleus that stabilizes itself by emitting ionizing radiation. // (rā′dē-ō-ı̄′sō-tōp) Unstable isotope that emits highenergy radiation (e.g., gamma rays) until it decays into a stable isotope.
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reactive oxygen species (ROS)
Highly reactive products of the partial reduction of O2, including hydrogen peroxide (H2O2), superoxide (•O2-), and hydroxyl free radical •OH, produced as minor byproducts during oxidative phosphorylation. // Successive transfer of electrons onto molecular oxygen, produces partially reduced intermediates that serve as oxidants and react with cell constituents such as unsaturated fatty acids, proteins, or nucleic acids. // Superoxide anion (O2 –) and hydrogen peroxide (H2O2), produced by phagocytic cells such as neutrophils and macrophages after ingestion of microbes, and which help kill the ingested microbes.
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receptor-mediated endocytosis
A type of pinocytosis in which molecules bound to proteins on the plasma membrane are taken in by infolding of the membrane. // Internalization of receptor– ligand complexes from the plasma membrane by endocytosis. // The internalization into endosomes of molecules bound to cell-surface receptors.
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renin // rennin
An enzyme produced in the kidney glomerulus in response to low blood volume, decreased blood pressure, or low sodium levels to stimulate a series of biochemical reactions to correct these changes. // The rate-limiting enzyme of angiotensin synthesis. // An enzyme that forms curds as part of any dairy fermentation product; originally from calves’ stomachs, now produced by molds and bacteria.
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resolution
The ability to distinguish fine detail with a magnifying instrument; also called resolving power. // The minimal size of an object that can be distinguished by microscopy or other methods of structural analysis. (Chapter 4) // The process by which a racemate is separated into its two pure enantiomers.
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restriction endonucleases
Site-specific endodeoxyribonucleases that cleave both strands of DNA at points in or near the specific site recognized by the enzyme; important tools in genetic engineering. // Bacterial enzymes that cleave specific palindromic sequences in double-stranded DNA. // Enzymes that are able to cleave a DNA molecule at points in the chain where a speciic base sequence occurs.
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reverse genetics
Genetic analysis that begins with a piece of DNA and proceeds to find out what it does. // Approach to discovering gene function that starts from the DNA (gene) and its protein product and then creates mutants to analyze the gene’s function. // Genetic approaches that use the nucleotide sequence of a gene to devise procedures for isolating mutations in the gene or shutting off its expression.
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RNA polymerase
An enzyme that catalyzes the synthesis of RNA. // Enzyme that catalyzes the synthesis of an RNA molecule on a DNA template from ribonucleoside triphosphate precursors. // RNA-synthesizing enzymes.
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RNA splicing
Removal of introns and joining of exons in a primary transcript. // Process in which intron sequences are excised from RNA transcripts. A major process in the nucleus of eukaryotic cells leading to formation of messenger RNAs (mRNAs). // The process by which introns, the regions of a primary RNA transcript that are not used to code protein, are removed.
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rough endoplasmic reticulum (rough ER)
A membrane-enclosed cellular organelle with ribosomes attached to its outer surface; a site of synthesis for proteins destined to be inserted into membrane or to be enclosed by membrane. // Endoplasmic reticulum with ribosomes on its cytosolic surface. Involved in the synthesis of secreted and membrane-bound proteins. // Endoplasmic reticulum with ribosomes on its surface.
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salt
A substance that dissolves in water to cations and anions, neither of which is H+ or OH-. // An ionic compound formed in a neutralization reaction by the replacement of an H+ ion from the acid with a cation from the base. // Substance formed by an ionic bond (e.g., NaCl).
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sarcolemma
(sar′kō-lem′ă) Plasma membrane of a muscle cell. // The outer cell membrane of a skeletal muscle fiber. // The plasma membrane of a muscle fiber.
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saturated fatty acid // saturated
A fatty acid that does not contain any double bonds in the hydrocarbon chain. // A fatty acid containing a fully saturated alkyl chain. // Fatty acids without C═C double bond.
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selectin
Member of a family of cell-surface carbohydratebinding proteins that mediate transient, Ca2+-dependent cell–cell adhesion in the bloodstream—for example between white blood cells and the endothelium of the blood vessel wall. // A large family of membrane proteins, lectins that bind oligosaccharides on other cells tightly and specifically and serve to carry signals across the plasma membrane. // Family of cell-adhesion molecules on leukocytes and endothelial cells that bind to sugar moieties on specific glycoproteins with mucin-like features.
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septum
(sep′tŭm; pl., septa) Wall of tissue separating nearby chambers; e.g., nasal septum. // A cross-wall in a fungal hypha. // Structure formed during bacterial cell division by the inward growth of the cell wall and plasma membrane and that divides the cell into two.
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SH2 domain
A domain of many signal transducing proteins that binds to phosphotyrosine groups on proteins. // A protein domain that binds tightly to a phosphotyrosine residue in certain proteins such as the receptor Tyr kinases, initiating the formation of a multiprotein complex that acts in a signaling pathway. // Src homology region 2, a protein domain present in many signaling proteins. Binds a short amino acid sequence containing a phosphotyrosine.
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short tandem repeat (STR) (microsatellite)
A short (typically 3 to 6 bp) DNA sequence, repeated many times in tandem at a particular location in a chromosome. // A highly polymorphic tandem repeat of a sequence only two to five nucleotide pairs in length. // Repeating sequences of two to five nucleotides.
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signal sequence
An amino acid sequence, often at the amino terminus, that signals the cellular fate or destination of a newly synthesized protein. // Short continuous sequence of amino acids that determines the eventual location of a protein in the cell. An example is the N-terminal sequence of 20 or so amino acids that directs nascent secretory and transmembrane proteins to the endoplasmic reticulum. // An amino acid sequence at the amino end of secreted proteins that directs them to the endoplasmic reticulum.
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small nuclear RNA (snRNA)
Small RNA molecules that are complexed with proteins to form the ribonucleoprotein particles (snRNPs) involved in RNA splicing. // A class of short RNAs, typically 100 to 200 nucleotides long, found in the nucleus and involved in the splicing of eukaryotic mRNAs. // Small RNA molecules that are located in the nuclei of eukaryotic cells; most snRNAs are components of the spliceosomes that excise introns from pre-mRNAs.
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solute
A substance dissolved in another substance. // (sol′ūt) Substance dissolving in a solvent. // The minority component of a solution.
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Somatic cell
A cell that is a component of the body, in contrast with a germ cell that is capable, when fertilized, of reproducing the organism. // Any cell of a plant or animal other than cells of the germ line. From Greek soma, body. // All body cells except the germline cells.
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Somatic mutation
A mutation that occurs in the nonreproductive cells (somatic cells) of the body and is not transmitted to progeny (cf. Germinal mutation). // Mutation in a somatic (nongermline) cell. // In cancer, one or more detectable abnormalities in the DNA sequence of tumor cells that distinguish them from the normal somatic cells surrounding the tumor.
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starch
Polysaccharide composed exclusively of glucose units, used as an energy-storage material in plant cells. // A digestible polysaccharide consisting of straight chains of glucose that can have branching. // A polysaccharide that consists of glucose units bonded together by a-glycosidic linkages; the main energy storage medium for plants.
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substrate-level phosphorylation
Phosphorylation of ADP or some other nucleoside 5’-diphosphate coupled to the dehydrogenation of an organic substrate; independent of the electron-transfer chain. // The synthesis of ATP by direct transfer of a high-energy phosphate group from an intermediate metabolic compound to ADP. // The use of an energyrich metabolic intermediate for the synthesis of ATP or GTP.
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synaptic vesicle
Small neurotransmitter-filled secretory vesicle found at the axon terminals of nerve cells. Its contents are released into the synaptic cleft by exocytosis when an action potential reaches the axon terminal. // (si-nap′tik ves′ikl) Package of membrane enclosing neurotransmitter molecules in the synaptic knob. // A membrane-enclosed structure, about 50 nm in diameter, containing neurotransmitter and found at a site of synaptic contact.
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Systems biology
An approach in which experimental methods to identify all the components of a biological system and their interactions are linked to properties and functions of the system using computational models. (Chapter 1) // Integrated approach to elucidate the interrelations of complex biological systems at the ecosystem community and cellular and molecular levels. // The study of complex biochemical systems, integrating the functions of several to all of the macromolecules in a cell (RNA, DNA, proteins).
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telomerase
Enzyme that elongates telomere sequences in DNA, which occur at the ends of eukaryotic chromosomes. telomere End of a chromosome, associated with a characteristic DNA sequence that is replicated in a special way. Counteracts the tendency of the chromosome otherwise to shorten with each round of replication. From Greek telos, end, and meros, portion. // An enzyme that adds telomere sequences to the ends of eukaryotic chromosomes. // An RNA-containing enzyme that extends the telomeres.
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template strand
A strand of nucleic acid used by a polymerase as a template to synthesize a complementary strand, as distinct from the coding strand. // In transcription, the DNA strand that is copied to produce a complementary strand of RNA. // The DNA strand complementary to a newly synthesized DNA or RNA.
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thioester
A chemical compound formed from an esterification of a thiol (sulfur) group and a carboxyl group. // An ester of a carboxylic acid with a thiol or mercaptan. // A class of compounds with the RCOSR functional group.
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tight junction
Cell–cell junction that seals adjacent epithelial cells together, preventing the passage of most dissolved molecules from one side of the epithelial sheet to the other. // Beltlike cell-cell adhesion in epithelial tissues that impairs the diffusion of extracellular solutes and of membrane constituents. // The areas of contact between adjacent epithelial cells, circumscribing the cells at the apical edges of their lateral membranes. (Chapter 2)
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totipotent // totipotent cell (or nucleus)
Describes a cell that is able to give rise to all the different cell types in an organism. // An undifferentiated cell (or nucleus) such as a blastomere that when isolated or suitably transplanted can develop into a complete embryo. // Embryonic stem cells that can differentiate into any cell of the body or placenta.
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transducin
The trimeric G protein activated when light is absorbed by visual rhodopsin; activated transducin activates cGMP phosphodiesterase. // A G protein in retinal rod cells that mediates the effects of light exposure on a cyclic GMP–specific phosphodiesterase. // The G-protein that couples rhodopsin to the enzyme phosphodiesterase in rod photoreceptors.
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transferrin
One of several human iron-binding proteins that reduce iron available to a pathogen. // A glycoprotein in the plasma that transports iron from the tissues and bloodstream to the bone marrow, where it is reused in the formation of hemoglobin. // The iron transport protein in the blood.
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transmitter-gated ion channel (ion-channel-coupled receptor, ionotropic receptor)
A membrane protein forming a pore that is permeable to ions and gated by neurotransmitter. // Ion channel found at chemical synapses in the postsynaptic plasma membranes of nerve and muscle cells. Opens only in response to the binding of a specific extracellular neurotransmitter. The resulting inflow of ions leads to the generation of a local electrical signal in the postsynaptic cell. // Ion channel found at chemical synapses in the postsynaptic plasma membranes of nerve and muscle cells. Opens only in response to the binding of a specific extracellular neurotransmitter. The resulting inflow of ions leads to the generation of a local electrical signal in the postsynaptic cell.
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Transposase
An enzyme that catalyzes the movement of an insertion sequence or transposon. // An enzyme capable of cutting DNA and allowing integration and excision of transposable genetic elements into or from the genome of a host. // An enzyme that catalyzes the movement of a DNA sequence to a different site in a DNA molecule.
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troponin
A calcium-sensing regulatory protein on the thin filaments of striated muscle. // A complex of three regulatory proteins that assists in regulating muscle contraction. // A protein that binds Ca²⁺ in a skeletal muscle cell, thereby regulating the interaction of myosin and actin.
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ubiquinone
A low–molecular mass, nonprotein carrier in an electron transport chain; also called coenzyme Q. // Coenzyme Q, a lipid that carries hydrogen in the inner mitochondrial membrane. // Group includes a component of the mitochondrial respiratory chain; are antioxidants and can spare vitamin E in preventing anemia in monkeys, and in maintaining sperm motility in birds
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vaccination
The deliberate induction of adaptive immunity to a pathogen by injecting a dead or attenuated (nonpathogenic) live form of the pathogen or its antigens (a vaccine). // Inoculation of healthy individuals with attenuated or related microorganisms, or their antigenic products, to elicit an immune response that will protect against later infection by the corresponding pathogen. (Chapter 1) // The process of conferring immunity by administering a vaccine; also called immunization.
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vesicle
A small, spherical membranebounded particle with an internal aqueous compartment that contains components such as hormones or neurotransmitters to be moved within or out of a cell. // (1) A small serum-filled elevation of the skin. (2) Smooth oval bodies formed in plant roots by mycorrhizae. V factor NAD+ or NADP+. // (ves′i-kl) Closed cellular structure within the cytoplasm enclosed by membrane.
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vitamin
An organic substance required in small quantities in the diet of some species; generally functions as a component of a coenzyme. // A small organic molecule that must be obtained in the diet and is required in trace amounts for proper growth and function. // An organic compound required for an organism to live, that either cannot be synthesized or is not synthesized enough by the organism and thus needs to be obtained from the organism’s diet.
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wild type
The normal (unmutated) genotype or phenotype. // The customary phenotype or standard for comparison. // The original (often laboratory-adapted) virus from which mutants are selected and which is used as the basis for comparison. (Chapter 3)
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β oxidation
Oxidative degradation of fatty acids into acetyl-CoA by successive oxidations at the β-carbon atom; as distinct from oxidation. // The major pathway of fatty acid oxidation. // The removal of two carbon units from a fatty acid to form acetyl CoA.
