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Test #4 - 7&8
Chapter 7&8
| Question | Answer |
|---|---|
| feedback inhibition | (also called end-product inhibition) Regulation of a metabolic pathway by the concentration of one of its intermediates or, typically, its end product, which inhibits an enzyme in the pathway |
| constitutive enzymes | An enzyme that is synthesized continuously regardless of the nutrients available to the organism |
| inducible enzymes | An enzyme coded for by a gene that is sometimes active and sometimes inactive |
| enzyme induction | A mechanism whereby the genes coding for enzymes needed to metabolize a particular nutrient are activated by the presence of that nutrient |
| inducer | A substance that binds to and inactivates a repressor protein |
| operon | A sequence of closely associated genes that includes both structural genes and regulatory sites that control transcription |
| structural genes | A gene that carries information for the synthesis of a specific polypeptide |
| regulatory site | The promoter and operator regions of an operon |
| regulator gene | Gene that controls the expression of structural genes of an operon through the synthesis of a repressor protein |
| repressor | In an operon it is the protein that binds to the operator, thereby preventing transcription of adjacent genes |
| enzyme repression | Mechanism by which the presence of a particular metabolite represses the genes coding for enzymes used in its synthesis |
| attenuation | (1) A genetic control mechanism that terminates transcription of an operon prematurely when the gene products are not needed. (2) The weakening of the disease-producing ability of an organism |
| catabolite repression | Process by which the presence of a preferred nutrient (often glucose) represses the genes coding for enzymes used to metabolize some alternative nutrient |
| Genotype | The genetic information contained in the DNA of an organism |
| Phenotype | The specific observable characteristics displayed by an organism |
| point mutation | Mutation in which one base is substituted for another at a specific location in a gene |
| frameshift mutation | Mutation resulting from the deletion or insertion of one or more bases |
| deletion | The removal of one or more nitrogenous bases from DNA, usually producing a frameshift mutation |
| insertion | The addition of one or more bases to DNA, usually producing a frameshift mutation |
| auxotrophs | An organism that uses carbon dioxide gas to synthesize organic molecules |
| prototrophs | A normal, nonmutant organism (also called wild type) |
| Spontaneous mutations | A mutation that occurs in the absence of any agent known to cause changes in DNA; usually caused by errors during DNA replication |
| Induced mutation | A mutation produced by agents called mutagens that increase the mutation rate |
| mutagens | An agent that increases the rate of mutations |
| base analog | A chemical mutagen similar in molecular structure to one of the nitrogenous bases found in DNA that causes point mutations |
| Alkylating agent | A chemical mutagen that can add alkyl groups (—CH3) to DNA bases, altering their shapes and causing errors in base pairing |
| Deaminating agent | A chemical mutagen that can remove an amino group ( —NH2) from a nitrogenous base, causing a point mutation |
| acridine derivative | A chemical mutagen that can be inserted between bases of the DNA double helix, causing frameshift mutations |
| Radiation | Light rays, such as X-rays and ultraviolet rays, that can act as mutagens |
| dimer | Two adjacent pyrimidines bonded together in a DNA strand, usually as a result of exposure to ultraviolet rays |
| Light chain (L chain) | Smaller of the two identical pairs of chains constituting immunoglobulin molecules |
| Dark repair | Mechanism for repair of damaged DNA by several enzymes that do not require light for activation; they excise defective nucleotide sequences and replace them with DNA complementary to the unaltered DNA strand |
| Ames test | Test used to determine whether a particular substance is mutagenic, based on its ability to induce mutations in auxotrophic bacteria |
| Gene transfer | Movement of genetic information between organisms by transformation, transduction, or conjugation |
| recombination | The combining of DNA from two different cells, resulting in a recombinant cell |
| vertical gene transfer | Genes pass from parents to offspring |
| lateral, gene transfer | Genes pass from one organism to another within the same generation |
| transformation | A change in an organism's characteristics through the transfer of naked DNA |
| competence factor | A protein released into the medium that facilitates the uptake of DNA into a bacterial cell |
| Transduction | The transfer of genetic material from one bacterium to another by a bacteriophage |
| bacteriophage (also called phage) | A virus that infects bacteria |
| phage | A virus that infects bacteria |
| temperate phage | A bacteriophage that does not cause a virulent infection; rather its DNA is incorporated into the host cell chromosome, as a prophage, and replicated with the chromosome |
| prophage | The DNA of a lysogenic phage that has integrated into the host cell chromosome |
| lysogen | The combination of a bacterium and a temperate phage |
| lysogenic | Pertaining to a bacterial cell in the state of lysogeny |
| specialized transduction | Type of transduction in which the bacterial DNA transduced is limited to one or a few genes lying adjacent to a prophage that are accidentally included when the prophage is excised from the bacterial chromosome |
| generalized transduction | Type of transduction in which a fragment of DNA from the degraded chromosome of an infected bacteria cell is accidentally incorporated into a new phage particle during viral replication and thereby transferred to another bacterial cell |
| conjugation | (1) The transfer of genetic information from one bacterial cell to another by means of conjugation pili. (2) The exchange of information between two ciliates (protists) |
| plasmid | A small, circular, independently replicating piece of DNA in a cell that is not part of its chromosome and can be transferred to another cell |
| F plasmid | Fertility plasmid containing genes directing synthesis of proteins that form an F pilus (sex pilus, or conjugation pilus) |
| F- cells | Cell lacking the F plasmid; called recipient or female cell |
| F+ cell | Cell having an F plasmid; called donor or male cell |
| F pilus | A bridge formed from an F1 cell to an F2 cell for conjugation |
| high frequency of recombination (Hfr) strain | A strain of F+ bacteria in which the F plasmid is incorporated into the bacterial chromosome |
| initiating segment | That part of the F plasmid that is transferred to the recipient cell in conjugation with an Hfr bacterium |
| promiscuous | Plasmids that are self-transmissible (have genes for the formation of an F pilus) that transfer into species other than their own kind |
| resistance (R) plasmid | A plasmid that carries genes that provide resistance to various antibiotics or toxic metals |
| resistance transfer factor | A component of a resistance plasmid that implements transfer by conjugation of the plasmid |
| resistance (R) genes | A component of a resistance plasmid that confers resistance to a specific antibiotic or to a toxic metal |
| displacin | A molecule that displaces (removes) gene(s) from a chromosome |
| transposition | he process whereby certain genetic sequences in bacteria or eukaryotes can move from one location to another |
| transposable element | A mobile genetic sequence that can move from one plasmid to another plasmid or chromosome |
| transposon | A mobile genetic sequence that contains the genes for transposition as well as one or more other genes not related to transposition |
| colicin | A protein released by some strains of Escherichia coli that inhibits growth of other strains of the same organism |
| bacteriocins | A protein released by some bacteria that inhibits the growth of other strains of the same or closely related species |
| bacteriocinogen | A plasmid that directs production of a bacteriocin |
| Genetic engineering | The use of various techniques to purposefully manipulate genetic material to alter the characteristics of an organism in a desired way |
| Genetic fusion | A technique of genetic engineering that allows transposition of genes from one location on a chromosome to another location; the coupling of genes from two different operons |
| protoplast | A Gram-positive bacterium from which the cell wall has been removed |
| Protoplast fusion | A technique of genetic engineering in which genetic material is combined by removing the cell walls of two different types of cells and allowing the resulting protoplasts to fuse |
| Gene amplification | A technique of genetic engineering in which plasmids or bacteriophages carrying a specific gene are induced to reproduce at a rapid rate within host cells |
| recombinant DNA | DNA combined from two different species by restriction enzymes and ligases |
| transgenic | State of permanently changing an organism's characteristics by integrating foreign DNA (genes) into the organism |
| vector | (1) A self-replicating carrier of DNA; usually a plasmid, bacteriophage, or eukaryotic virus. (2) An organism that transmits a disease-causing organism from one host to another |
Created by:
sbiosweitz
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