BIO - TERMS - FREQUENCY > 1 PT 6 Flashcards
absolute configuration
The configuration of four different substituent groups around an asymmetric carbon atom, in relation to D- and L-glyceraldehyde. // The exact threedimensional structure of a chiral molecule. Absolute conigurations are specfied verbally by the Cahn–Ingold–Prelog R,S convention.
Acylation
Posttranslational addition of saturated or unsaturated fatty acids to a protein. (Chapter 12) // The introduction of an acyl group, -COR, onto a molecule. For example, acylation of an alcohol yields an ester, acylation of an amine yields an amide, and acylation of an aromatic ring yields an alkyl aryl ketone.
Affinity
The measure of the strength with which one molecule associates with another noncovalently. (Chapter 5) // The strength of binding of one molecule to another at a single site, such as the binding of a monovalent Fab fragment of antibody to a monovalent antigen. Cf. avidity.
alkyne
A hydrocarbon containing one or more carbon–carbon triple bonds. // A hydrocarbon that contains a carbon–carbon triple bond, RC≡CR.
AMPA receptor
A subtype of glutamate receptor; a glutamate-gated ion channel that is permeable to Na and K . // Glutamate-gated ion channel in the mammalian central nervous system that carries most of the depolarizing current responsible for excitatory postsynaptic potentials.
angiogenesis
(an′jē-ō-jen′ĕ-sis) Process of forming new blood vessels. // Growth of new blood vessels by sprouting from existing ones.
antisense strand (– strand)
Viral RNA that cannot act as mRNA. // The template, non coding strand of double-helical DNA that does not contain the gene.
artificial selection
Choosing one organism from a population to grow because of its desirable traits. // The practice of choosing individuals from a population for reproduction, usually because these individuals possess one or more desirable traits.
attenuator
An RNA sequence involved in regulating the expression of certain genes; functions as a transcription terminator. // A nucleotide sequence in the 5′ region of a prokaryotic gene (or in its RNA) that causes premature termination of transcription, possibly by forming a secondary structure.
Avidity
The sum of the affinities (strengths) of multiple noncovalent interactions. (Chapter 5) // The sum total of the strength of binding of two molecules or cells to one another at multiple sites. It is distinct from affinity, which is the strength of binding of one site on a molecule to its ligand.
beta (β) decay
The form of radioactive decay that occurs when an unstable nucleus emits an electron.
blastomere
One of the many cells formed by the cleavage of a fertilized egg. // Any one of the cells formed from the first few cleavages in animal development.
bursa of Fabricius
An organ in chickens responsible for maturation of the immune system. // Lymphoid organ associated with the gut that is the site of B-cell development in chickens.
carbocation
A positively charged carbon atom; also called a carbonium ion. // A carbon cation, or substance that contains a trivalent, positively charged carbon atom having six electrons in its outer shell (R3C+).
CD8
The co-receptor for T-cell receptors that recognize peptide antigens bound to MHC class I molecules. It binds to the lateral face of the MHC molecule. // Co-receptor protein on cytotoxic T cells that binds to a nonvariable part of class I MHC proteins (on antigen-presenting cells and infected target cells) outside the peptide-binding groove.
chemical bond
An attractive force between atoms forming a molecule. // The sharing or transfer of electrons to attain stable electron configurations for the bonding atoms.
Chirality
Optical isomerism, created by alternative configurations of substituents around an asymmetric carbon.
cistern // cisterna
A flattened membranous sac in endoplasmic reticulum and the Golgi complex. // (sis-ter′nă; pl., cisternae, -ter′nē) Enclosed microscopic space; e.g., between the parallel membranes of the Golgi apparatus.
Colchicine
An alkaloid that inhibits the formation of microtubules. // An alkaloid derived from the autumn crocus that is used as an agent to arrest spindle formation and interrupt mitosis.
concentration gradient
(grā′dē-ent) Difference in the concentration of a substance between two areas. // A difference in concentration from one region to another. Ionic concentration gradients across the neuronal membrane help determine the membrane potential.
constant region, C region
In immunology: region of an immunoglobulin or T cell receptor chain that has a constant amino acid sequence. // That part of an immunoglobulin or a T-cell receptor that is relatively constant in amino acid sequence between different molecules. Also known as the Fc region in antibodies. The constant region of an antibody determines its particular effector function. Cf. variable region.
cornea
(kōr′nē-ă) Transparent structure that forms the anterior surface of the eye. // The transparent external surface of the eye.
cytology
(sı̄-tol′ō-jē) Study of cells. // The study of the structure and function of cells.
Desaturases
Enzymes that introduce double bonds into fatty acids. // Enzymes that catalyze the introduction of double bonds into the hydrocarbon portion of fatty acids.
digestion
Enzymatic hydrolysis of major nutrients in the gastrointestinal system to yield their simpler components. // The irst stage of catabolism, in which food is broken down by hydrolysis of ester, gly coside (acetal), and peptide (amide) bonds to yield fatty acids, simple sugars, and amino acids.
DNA cloning
The process of amplifying a specific sequence of DNA. // (1) The act of making many identical copies (typically billions) of a DNA molecule—the amplification of a particular DNA sequence. (2) Also, the isolation of a particular stretch of DNA (often a particular gene) from the rest of the cell’s genome.
donor cell
A cell that gives DNA to a recipient cell during genetic recombination. // A bacterium that donates DNA to another (recipient) cell during recombination in bacteria (cf. Recipient cell).
Ectopic
A term used to describe a phenomenon that occurs in an abnormal place. // (ek-top′ik) Out of place; e.g., in an ectopic pregnancy, the pre-embryo implants in the uterine tube rather than in the uterus.
electron microscope
Microscope that uses a beam of electrons to create the image. // A microscope that uses electrons instead of light to produce an image.
Endonuclease
An enzyme that breaks strands of DNA at internal positions; some are involved in recombination of DNA. // Enzymes that hydrolyze the interior phosphodiester bonds of a nucleic acid—that is, act at bonds other than the terminal bonds.
Epidemic // epidemic disease
A disease acquired by many hosts in a given area in a short time. // A pattern of disease characterized by rapid and sudden appearance of cases spreading over a wide area. (Chapter 1)
eukaryotic initiation factor (eIF)
Protein that helps load initiator tRNA on to the ribosome, thus initiating translation. // A combination of proteins needed to initiate translation and protein synthesis on the ribosomes.
fatigue
A general sense of tiredness that is often accompanied by a decrease in muscular performance. // Reduction in athletic performance that stems from physiologic events in muscle (peripheral fatigue) or the central nervous system (central fatigue).
First-order reaction
Reaction whose velocity is proportional to the concentration of a substrate. // Designates a reaction whose rate-limiting step is unimolecular and whose kinetics therefore depend on the concentration of only one reactant.
follicular helper T cell (TFH)
Type of effector CD4 T cell that resides in lymphoid follicles and provides help to B cells for antibody production. // Type of T cell located in lymphoid follicles that secretes various cytokines to stimulate B cells to undergo antibody class switching and somatic hypermutation.
Gall
A tumorous growth in plants. // Issue deformations found in plants infected by certain microorganisms or colonized by insects.
gene conversion
Process by which DNA sequence information can be transferred from one DNA helix (which remains unchanged) to another DNA helix whose sequence is altered. It often accompanies general recombination events. // A process, often associated with recombination, during which one allele is replicated at the expense of another, leading to non-Mendelian segregation ratios. In whole tetrads, for example, the ratio may be 6:2 or 5:3 instead of the expected 4:4.
Glucocorticoid
A steroid hormone that regulates gene expression in higher animals. // (glū-kō-kōr′tikōyd) Group of hormones released from the adrenal cortex; help regulate glucose levels; e.g., cortisol, corticosteroid.
goblet cells
Unicellular glands that secrete mucin. // Specialized epithelial cells located in many sites throughout the body responsible for mucus production; important in protection of the epithelium.
granzymes
Proteases that induce apoptosis. // Members of a family of serine proteases that are released from activated cytotoxic T cells and induce apoptosis of target cells. (Chapter 4)
