BIO - TERMS - FREQUENCY > 1 PT 8

Question 1

absorption

Answer 1

(ab-sōrp-shŭn) Process of moving substances, such as products of digestion, into the blood or lymph. // Transport of the products of digestion from the intestinal tract into the blood. acceptor control Regulation of the rate of respiration by the availability of ADP as phosphate group acceptor.

Question 2

addition reaction

Answer 2

A type of organic reaction in which two substituents are added across a double bond. // Occur when two reactants add together to form a single product with no atoms left over.

Question 3

agglutination

Answer 3

A joining together or clumping of cells. // (ă-glū-ti-nā′shŭn) Process by which cells clump due to cross-linking by antibodies.

Question 4

allosteric site

Answer 4

The site on an enzyme at which a noncompetitive inhibitor binds. // The specific site on the surface of an allosteric enzyme molecule to which the modulator or effector molecule is bound.

Question 5

amphoteric

Answer 5

Able to act as either an acid or a base. // Capable of donating and accepting protons, thus able to serve as an acid or a base.

Question 6

Angstrom (Å)

Answer 6

A unit of measurement equal to 10-10 m, or 0.1 nm. // A unit of length (10⁻⁸ cm) used to indicate molecular dimensions.

Question 7

aorta

Answer 7

(ā-ōr′tă) Main trunk of the systemic arterial system, beginning at the left ventricle and ending when it forks at its inferior end to form the common iliac arteries. // The major blood vessel exiting the heart at the left ventricle to carry blood to the body. avidin A protein found in egg whites that binds tightly to biotin.

Question 8

Ascus (pl, asci)

Answer 8

A saclike structure containing ascospores; found in the ascomycetes. // Reproductive sac in the sexual stage of a type of fungi (Ascomycetes) in which ascospores are produced.

Question 9

autocrine

Answer 9

Describes a cytokine or other biologically active molecule acting on the cell that produces it. // (aw′tō-krin) Hormonal secretions that stimulate the same cell that released it; also called a local hormone (does not enter the blood). Compare to endocrine.

Question 10

axon

Answer 10

(ak′son) Process of a neuron that propagates action potentials away from the cell body. // A neurite specialized to conduct nerve impulses, or action potentials, normally away from the soma.

Question 11

beta sheet (β sheet)

Answer 11

Common structural motif in proteins in which different sections of the polypeptide chain run alongside each other, joined together by hydrogen-bonding between atoms of the polypeptide backbone. Also known as a β pleated sheet. // A secondary protein structure composed of β strands stabilized by noncovalent interactions between backbone amide and carbonyl groups. In ‘parallel’ β sheets, the adjacent strands run in the same direction; in ‘antiparallel’ β sheets, adjacent strands run in opposite directions. Immunoglobulin domains are made up of two antiparallel β sheets arranged in the form of a β barrel.

Question 12

blebbing

Answer 12

Bulging of plasma membrane as a cell dies. // Membrane protrusion formed when the plasma membrane detaches locally from the underlying actin cortex, allowing cytoplasmic flow and hydrostatic pressure within the cell to push the membrane outward.

Question 13

C3

Answer 13

The pivotal complement protein that is activated by the early components of all three complement pathways (the classical pathway, the lectin pathway, and the alternative pathway). // Complement protein on which all complement activation pathways converge. C3 cleavage forms C3b, which can bind covalently to microbial surfaces, where it promotes destruction by phagocytes.

Question 14

Carbonyl group

Answer 14

The C5O functional group. // A functional group consisting of a carbon atom double-bonded to an oxygen atom (C=O).

Question 15

cell

Answer 15

The smallest functioning living unit. // Basic structural and functional unit of a living organism.

Question 16

chemical synapse

Answer 16

A synapse in which presynaptic activity stimulates the release of neurotransmitter, which activates receptors in the postsynaptic membrane. // (sin′aps) Junction between two communicating cells (neurons, and neurons and effectors); neurotransmitter released at this type of synapse.

Question 17

chlorophyll

Answer 17

Light-absorbing green pigment that plays a central part in photosynthesis in bacteria, plants, and algae. // A family of green pigments that function as receptors of light energy in photosynthesis; magnesium-porphyrin complexes.

Question 18

classes

Answer 18

The class of an antibody is defined by the type of heavy chain it contains. There are five main antibody classes: IgA, IgD, IgM, IgG, and IgE, containing heavy chains α, δ, μ, γ, and ε, respectively. The IgG class has several subclasses. See also isotypes.

Question 19

colligative property

Answer 19

A property that depends on the amount of a solute but not on the type. // Properties of a solution that depend on the number of solute particles per unit volume; for example, freezingpoint depression.

Question 20

Conidium (pl, conidia)

Answer 20

An asexual spore produced in a chain from a conidiophore. // An asexual spore produced by a specialized hypha in certain fungi.

Question 21

constitutive gene

Answer 21

A gene that is produced continuously. // A gene that is continually expressed in all cells of an organism.

Question 22

Cretinism

Answer 22

The result of untreated congenital hypothyroidism; characterized by mental deficiency and growth retardation. // A congenital condition due to low maternal iodine intake during pregnancy that leads to stunted mental and physical growth.

Question 23

death-inducing signaling complex (DISC)

Answer 23

Activation complex in which initiator caspases interact and are activated following binding of extracellular ligands to cell-surface death receptors in the extrinsic pathway of apoptosis. // A multi-protein complex that is formed by signaling through members of the ‘death receptor’ family of apoptosis-inducing cellular receptors, such as Fas. It activates the caspase cascade to induce apoptosis.

Question 24

desiccation

Answer 24

The removal of water. // Drying of an organism.

Question 25

dimorphism

Answer 25

The property of having two forms of growth. See also sexual dimorphism. // Two different forms in a group as determined by such characteristics as sex, size, or coloration.

Question 26

DNA helicase

Answer 26

An enzyme that catalyzes the unwinding of the complementary strands of a DNA double helix. // Enzyme that is involved in opening the DNA helix into its single strands for DNA replication.

Question 27

Double bond

Answer 27

A covalent bond formed by sharing two electron pairs between atoms. // The bond that forms when two electrons are shared between two atoms.

Question 28

efferent

Answer 28

(ef′er-ent) Outgoing or moving away from a center. // An axon originating in and coursing away from a given structure. See also afferent.

Question 29

electrophile

Answer 29

An electron-deficient group with a strong tendency to accept electrons from an electron-rich group (nucleophile). // An “electron-lover,” or substance that accepts an electron pair from a nucleophile in a polar bondforming reaction.

Question 30

endosteum

Answer 30

(en-dos′tē-ŭm) Layer of cells lining the inner surface of bone in the medullary cavity. // The region in bone marrow adjacent to the inner surface of the bone; hematopoietic stem cells are initially located there.

Question 31

Epigenetic

Answer 31

A term referring to the nongenetic causes of a phenotype. // Describes any inherited characteristic of a living organism that is acquired by means that do not involve the nucleotide sequence of the parental chromosomes; for example, covalent modifications of histones.

Question 32

exotoxin

Answer 32

A protein toxin produced and secreted by a bacterium. // A protein toxin released from living, mostly gram-positive bacterial cells.

Question 33

Fc // Fc fragment, Fc region

Answer 33

The crystallizable fragment of immunoglobulins, formed from the carboxyl-terminal halves of the heavy chains. // The carboxy-terminal halves of the two heavy chains of an IgG molecule disulfide-bonded to each other by the residual hinge region. It is produced by cleavage of IgG by papain. In the complete antibody this portion is often called the Fc region.

Question 34

Fixation

Answer 34

An event that occurs when all the alleles at a locus except one are eliminated from a population. The remaining allele, with frequency 100 percent, is said to have been fixed. // Process to preserve biological tissue in a “nearto- life” status for histological analyses; it immobilizes cell components and terminates any biochemical reaction by the use of suitable substances (chemical fixation) or by rapid freezing (cryofixation).

Question 35

formal charge

Answer 35

The difference in the number of electrons owned by an atom in a molecule and by the same atom in its elemental state. // The charge that an atom in a Lewis structure would have if all the bonding electrons were shared equally between the bonded atoms.

Question 36

gamma (γ) ray

Answer 36

The form of electromagnetic radiation with the shortest wavelength and highest energy.

Question 37

generalized transduction

Answer 37

The transfer of bacterial chromosome fragments from one cell to another by a bacteriophage. // Recombination in bacteria mediated by a bacteriophage that can transfer any bacterial gene of the donor cell to a recipient cell (cf. Specialized transduction).

Question 38

Glucose transporter 4 (GLUT-4)

Answer 38

An insulin-dependent glucose carrier in muscle and adipose tissue. // (GLUT4)—A contraction-sensitive glucose transport protein that aids in the uptake of glucose by working skeletal muscle.

Question 39

Golgi tendon organ

Answer 39

A sensory receptor that monitors tension and is located in the muscle tendon. // A specialized structure within the tendons of skeletal muscle that senses muscle tension.

Question 40

gray matter

Answer 40

A generic term for a collection of neuronal cell bodies in the central nervous system. When a freshly dissected brain is cut open, neurons appear gray. See also white matter.

Question 41

Helicases

Answer 41

Enzymes separating the strands of doublestranded DNA. // Enzymes that catalyze the separation of strands in a DNA molecule before replication.

Question 42

hepatocyte

Answer 42

The major cell type of liver tissue. // Highly specialized liver cell that is involved in the metabolism of energy nutrients, including the storage of glycogen, gluconeogenesis, and urea production.

Question 43

host range

Answer 43

The spectrum of species, strains, or cell types that a pathogen can infect. // A listing of species and cells (hosts) that are susceptible to and permissive for infection. (Chapter 5)

Question 44

hydroxyl // hydroxyl group

Answer 44

An -OH group. // —OH; covalently bonded to a molecule forms an alcohol.

Question 45

hypokalemia

Answer 45

An electrolyte imbalance characterized by low levels of blood potassium. // An abnormal condition in which blood potassium levels are lower than normal.

Question 46

immunological memory

Answer 46

The ability of the immune system to respond more rapidly and more effectively on a second encounter with an antigen. Immunological memory is specific for a particular antigen and is long-lived. // Long-lived property of the adaptive immune system that follows a primary immune response to many antigens, such that a subsequent encounter with the same antigen will provoke a more rapid and stronger secondary immune response.

Question 47

Incubation period

Answer 47

Th e period before symptoms of disease appear aft er an infection. (Chapter 5) // The time interval between the actual infection and first appearance of any signs or symptoms of disease.

Question 48

Initiator

Answer 48

A short DNA sequence that is sufficient to specify the site at which RNA polymerase II initiates transcription. (Chapter 8) // A substance that is used to initiate a radical chain reaction or polymerization. For example, radical chlorination of alkanes is initiated when light energy breaks the weak Cl-Cl bond to form Cl· radicals.

Question 49

intensity

Answer 49

The amplitude of a sound wave. Sound intensity is the amplitude of the pressure differences in a sound wave that perceptually determines loudness. // The qualitative element of training such as speed, maximum strength, and power. In strength training, intensity is often expressed in load related to the 1RM.

Question 50

isotonic solution

Answer 50

Contains the same relative solute and water concentration as the cytosol. // A solution in which, after immersion of a cell, osmotic pressure is equal across the cell’s membrane.

Question 51

Knockout mouse

Answer 51

A mouse in which a gene has been disrupted by genetic manipulations. // Mice in which a gene of interest has been silenced or deleted by genetic engineering.

Question 52

leader // Leader sequence

Answer 52

The segment of an mRNA molecule from the 5′ terminus to the translation initiation codon. // A short sequence near the amino terminus of a protein or the 5’ end of an RNA that has a specialized targeting or regulatory function.

Question 53

Lewis symbol

Answer 53

The symbol of an element surrounded with dots representing the element’s valence electrons.

Question 54

Littoral zone

Answer 54

Shore region of lakes and oceans. // The region along the shore of the ocean or a large lake where there is considerable vegetation and where light penetrates to the bottom.

Question 55

macropinocytosis

Answer 55

Clathrin-independent, dedicated degradative endocytic pathway induced in most cell types by cell-surface receptor activation by specific cargoes. // A process in which large amounts of extracellular fluid are taken up into an intracellular vesicle. This is one way in which dendritic cells can take up a wide variety of antigens from their surroundings.

Question 56

Metabolome

Answer 56

Entirety of all metabolites in an organism. // The complete set of smallmolecule metabolites (metabolic intermediates, signals, secondary metabolites) present in a given cell or tissue under specific conditions.

Question 57

Michaelis constant (Km)

Answer 57

The substrate concentration at which the rate of an enzymatic reaction is half maximal. // The substrate concentration at which an enzyme-catalyzed reaction proceeds at one-half its maximum velocity.

Question 58

molar volume

Answer 58

The volume occupied by 1 mol of a substance; the molar volume of an ideal gas at STP is 22.4 L.

Question 59

mucin

Answer 59

(mū′sin) A carbohydraterich glycoprotein that forms mucus when hydrated. // Highly glycosylated cell-surface proteins. Mucin-like molecules are bound by L-selectin in lymphocyte homing.

Question 60

myelin

Answer 60

(mı̄′ĕ-lin) Insulating covering around an axon composed of concentric layers of plasma membrane of glial cells (neurolemmocytes or oligodendrocytes). // A membranous wrapping, or sheath, around axons provided by oligodendroglia in the central nervous system and Schwann cells in the peripheral nervous system.

Question 61

Netrin

Answer 61

Signal protein, secreted by cells of the neural tube floor plate, responsible for attracting growth cones of commissural axons toward and across the midline. // An axonal guidance module; a protein secreted by cells in specific locations in the developing CNS that can act as either an axonal attractant or a repellent, depending on the type of netrin receptor expressed on the growing axon.

Question 62

nitrification

Answer 62

The oxidation of nitrogen in ammonia to produce nitrate. // Oxidation of ammonia to nitrite and nitrate.

Question 63

Nonhomologous end-joining (NHEJ)

Answer 63

A mechanism that repairs broken DNA molecules by joining the broken ends together, often changing the DNA sequence around the junction. // A DNA repair mechanism for double-strand breaks in which the broken ends of DNA are brought together and rejoined by DNA ligation, generally with the loss of one or more nucleotides at the site of joining.

Question 64

obesity

Answer 64

State of excessive body fat; body fat of 25% or more of total mass for men and 33% or more for women. // A state of positive energy balance in which energy intake and storage exceed energy expenditure, resulting in an increase in body fat. See also starvation.

Question 65

optogenetics

Answer 65

A method that allows the control of neuronal activity, comprising the introduction of foreign genes into neurons that express membrane ion channels that open in response to light. // Use of genetically engineered channelrhodopsin and other light-responsive ion channels and transporters to modulate neuron function and hence analyze the neurons and circuits underlying complex functions, including behaviors in whole animals.

Question 66

orphan receptor

Answer 66

Proteins that resemble known receptors but whose natural ligands are unknown. // A cellular nuclear receptor in which a ligandactivating compound was originally not known. The receptors bind to promoters of genes to initialize gene transcription.

Question 67

Papillomavirus

Answer 67

A DNA virus associated with cervical cancer. // Class of viruses responsible for human warts and a prime example of DNA tumor viruses, being a cause of cancer of the uterine cervix.

Question 68

pathogenic

Answer 68

(path′ō-jen-ik) Capable of infecting and causing disease.

Question 69

pernicious anemia

Answer 69

A megaloblastic macrocytic anemia caused by the lack of intrinsic factor that leads to a vitamin B12 deficiency. // Megaloblastic anemia and neuropathy caused by vitamin B12 malabsorption.

Question 70

phosphofructokinase (PFK)

Answer 70

The rate-limiting enzyme of the glycolytic system. // The enzyme that catalyzes the committed step of glycolysis.

Question 71

phototropin

Answer 71

Photoprotein associated with the plant plasma membrane that senses blue light and is partly responsible for phototropism. // Blue/UV-A light photoreceptor that triggers light-mediated movement processes in plants; uses two LOV domains as light sensor module.

Question 72

plasmodesma (plural plasmodesmata)

Answer 72

A channel allowing symplastic transport of molecules between two plant cells. // Plant equivalent of a gap junction. Communicating cell–cell junction in plants in which a channel of cytoplasm lined by plasma membrane connects two adjacent cells through a small pore in their cell walls.

Question 73

polynucleotide

Answer 73

A covalently linked sequence of nucleotides in which the 3’ hydroxyl of the pentose of one nucleotide residue is joined by a phosphodiester bond to the 5’ hydroxyl of the pentose of the next residue. // A linear sequence of joined nucleotides in DNA or RNA.

Question 74

position effect variegation

Answer 74

Alteration in gene expression resulting from change in the position of the gene in relation to other chromosomal domains, especially heterochromatic domains. When an active gene is placed next to heterochromatin, the inactivating influence of the heterochromatin can spread to affect the gene to a variable degree, giving rise to position effect variegation. // Phenotypic variation within an individual that is due to a change in the genomic position of a gene. Usually this type of variation is seen when a gene naturally located in euchromatin is moved by a chromosome rearrangement to a heterochromatic region of the genome.

Question 75

primosome

Answer 75

An enzyme complex that synthesizes the primers required for lagging strand DNA synthesis. // A protein replication complex that catalyzes the initiation of Okazaki fragments during discontinuous DNA synthesis. It contains DNA primase and DNA helicase activities.

Question 76

purifying selection

Answer 76

Natural selection operating in a population to slow genome changes and reduce divergence by eliminating individuals carrying deleterious mutations. // A form of natural selection that removes detrimental mutations from the gene pool.

Question 77

radioimmunoassay (RIA)

Answer 77

A highly sensitive analytical method used for the determination of hormone levels. // A sensitive, quantitative method for detecting trace amounts of a biomolecule, based on its capacity to displace a radioactive form of the molecule from combination with its specific antibody.

Question 78

redox pair

Answer 78

Pair of molecules in which one acts as an electron donor and one as an electron acceptor in an oxidation– reduction reaction: for example, NADH (electron donor) and NAD+ (electron acceptor). // An electron donor and its corresponding oxidized form; for example, NADH and NAD.

Question 79

renaturation

Answer 79

Refolding of an unfolded (denatured) globular protein so as to restore its native structure and function. // The restoration of a molecule to its native form. In nucleic acid biochemistry, this term usually refers to the formation of a double-stranded helix from complementary single-stranded molecules.

Question 80

resonance hybrid

Answer 80

The actual structure of a molecule that is intermediate between two or more resonance structures. // A molecule, such as benzene, that can’t be represented adequately by a single Kekulé structure but must instead be considered as an average of two or more resonance forms. The resonance forms themselves differ only in the positions of their electrons, not their nuclei.

Question 81

retroviral-like retrotransposons // retroviruslike element

Answer 81

A large family of transposons that move themselves in and out of chromosomes by a mechanism similar to that used by retroviruses, being first transcribed into an RNA copy that is converted to DNA by reverse transcriptase then inserted elsewhere in the genome. // A type of retrotransposon that resembles the integrated form of a retrovirus.

Question 82

Sanger dideoxy method // Sanger method

Answer 82

A commonly used method of DNA sequencing. // Standard method in genomics for DNA sequencing using the principle of chain termination providing long sequence reads up to 1 kb with high quality.

Question 83

sclera

Answer 83

(skler′ă) Portion of the fibrous layer forming the outer covering of the eye, except for the cornea; “white” of the eye. // The tough outer wall of the eyeball; the white of the eye.

Question 84

semipermeable membrane

Answer 84

(sem′ē-per′mē-ă- bl) Freely permeable to some molecules, but relatively non-permeable to other molecules. // A membrane that selectively allows some substances to pass through but not others.

Question 85

side chain

Answer 85

The part of an amino acid that differs between amino acid types. The side chains give each type of amino acid its unique physical and chemical properties. // The substituent attached to the α carbon of an amino acid.

Question 86

single-strand DNA-binding (SSB) protein

Answer 86

Protein that binds to the single strands of the opened-up DNA double helix, preventing helical structures from reforming while the DNA is being replicated. // A protein that coats DNA single strands, keeping them in an extended state.

Question 87

Southern blotting

Answer 87

A technique that uses DNA probes to detect the presence of specific DNA in restriction fragments separated by electrophoresis. // A method using a probe for the identification of DNA fragments after gel electrophoresis.

Question 88

spike

Answer 88

A carbohydrate-protein complex that projects from the surface of certain viruses.

Question 89

steroid hormones

Answer 89

Hormones, including cortisol, estrogen, and testosterone, that are hydrophobic lipid molecules derived from cholesterol that activate intracellular nuclear receptors.

Question 90

sulcus

Answer 90

(sūl′kŭs; pl., sulci, sŭl′sı̄) Groove or furrow; e.g., on the surface of the brain. // A groove in the surface of the cerebrum running between neighboring gyri. Plural: sulci.

Question 91

systolic blood pressure // systolic pressure

Answer 91

The maximum blood pressure exerted by the blood against the walls of the blood vessels composing the cardiovascular system when the heart contracts. // Blood pressure measured in an artery during systole.

Question 92

termination sequence

Answer 92

A DNA sequence, at the end of a transcriptional unit, that signals the end of transcription.

Question 93

TH17

Answer 93

A subset of CD4 T cells that are characterized by production of the cytokine IL-17. They help recruit neutrophils to sites of infection.

Question 94

thymocytes

Answer 94

Developing T cells in the thymus. // Developing T cells when they are in the thymus. The majority are not functionally mature and are unable to mount protective T-cell responses.

Question 95

trans

Answer 95

Hydrogen atoms on opposite side across a double bond in a fatty acid. See cis. // On opposing sides of a double bond. In terms of fatty acids, each hydrogen atom is on opposite sides of a double bond.

Question 96

translational control

Answer 96

The regulation of a protein’s synthesis by regulation of the rate of its translation on the ribosome. // Regulation by a cell of gene expression by selecting which mRNAs in the cytoplasm are translated by ribosomes.

Question 97

Tubulin

Answer 97

A globular protein that polymerizes into microtubules. // The major protein component of the microtubules of eukaryotic cells.

Question 98

urea

Answer 98

(ū-rē′ă) A nitrogenous waste produced from breakdown of amino acids; eliminated in urine. // The major nitrogen-containing waste product in urine.

Question 99

van der Waals attraction

Answer 99

Type of (individually weak) noncovalent bond that is formed at close range between nonpolar atoms.

Question 100

Vitamin B complex

Answer 100

Term introduced when it became clear that “water-soluble B” contained more than one biologically active substance (such preparations were subsequently found to be mixtures of thiamin, niacin, riboflavin, pyridoxine, and pantothenic acid); the term has contemporary lay use as a nonspecific name for all of the B-designated vitamins

Question 101

wavelength (λ)

Answer 101

The distance between adjacent crests of a wave. // The length of a wave from peak to peak. The wavelength of electromagnetic radiation is inversely proportional to frequency and inversely proportional to energy.

Question 102

zinc finger protein

Answer 102

A DNA-binding, fingerlike polypeptide projection caused by zinc binding to specific histidine and cysteine residues. Allows for proteins to bind to DNA promoters. // A type of DNA-binding protein.