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Chapters 6, 7 9 & 11
Definitions
| Term | Definition |
|---|---|
| Acidophile | an organism that thrives in a relatively acid environment |
| Active transport | Nutrient transport method that requires carrier proteins in the membranes of the living cells and the expenditure of energy. |
| Ames test | A method for detecting mutagenic and potentially carcinogenic agents based upon the genetic alteration of nutritionally defective bacteria. |
| Amino acid | The building blocks of protein. Amino acids exist in 20 naturally occurring forms that impart different characteristics to the various proteins they compose. |
| Anaerobe | A microorganism that grows best or exclusively in an environment lacking oxygen. |
| Antiparallel | The opposite orientation of the two complementary strands or deoxyribonucleic acid, 5 to 3 and 3 to 5. |
| Antisepsis | Chemical treatment to kill or inhibit the growth of all vegetative microorganisms on body surfaces. |
| Autotroph | A microorganism that requires only inorganic nutrients and whose sole source of carbon is carbon dioxide. |
| Back mutation | A mutation that counteracts an earlier mutation, resulting in the restoration of the original DNA sequence. |
| Bacteriocidal | A substance which only kills bacteria. |
| Bacteriostatic | Any agent which which inhibits the growth of bacteria. |
| Binary fision | The formation of of two new cells of approximately equal as the result of parent cell division. |
| Capsid | The protein covering of a virus' nucleic acid core. Capsids exhibit symmetry due to the regular arrangement of subunits called capsomers. |
| Capsomer | A subunit of the virus capsid shape as a triangle or disc. |
| Catalase | An enzyme that catalyzes the reduction of hydrogen peroxide. |
| Commensal | A symbiotic relationship in which one species benefits while the other is unaffected. |
| Conjugation | The contact between donor and recipient cells associated with the transfer of genetic material such as plasmids. Can involve special (sex) pili. Also a form of sexual recombination in ciliated protozoans. |
| Contaminant | An impurity, any undesirable material or organism. |
| Death phase | End of the cell growth due to lack of nutrition, depletion of environment and accumulation of wastes. Population of cells begins to die. |
| Decontamination | The removal or neutralization of an infectious, poisonous, or injurious agent from a site. |
| Degermation | The process by which you are physically removing surface oils, debris and soil from skin to reduce the microbial load. |
| Denature | The loss of normal characteristics resulting from some molecular alteration. Usually in reference to the action of heat or chemicals on proteins whose function depends upon an unaltered tertiary structure. |
| Diffusion | The dispersal of molecules, ions, or microscopic particles propelled down a concentration gradient b spontaneous random motion to achieve a uniform distribution. |
| Disinfection | The destruction of pathogenic nonsporulating microbes or their toxins, usually on inanimate surfaces. |
| DNA gyrase | is an enzyme that relieves strain while double-stranded DNA is being unwound by helicase. This causes negative supercoiling of the DNA. |
| Dry heat | Utilizes hot air that is either free from water vapour, or has very little of it, and where this moisture plays a minimal or no role in the process of sterilization |
| Endocytosis | The process by which solid and liquid materials are taken into the cell through membrane invagination and engulfment into a vesicle. |
| Ethylene oxide | A potent, highly water-soluble gas invaluable for gaseous sterilization of heat-sensitive objects such as plastics, surgical and diagnostic appliances and spices. |
| Exon | A stretch of eukaryotic DNA coding for a corresponding portion of mRNA that is translated into peptides. Intervening stretches of DNA that are not expressed are called introns. During transcription, exons are separated from introns and are spliced toget |
| Exon (cont'd.) | together into a continuous mRNA transcript. |
| Extremophile | Organisms capable of living in harsh environments, such as extreme heat or cold. |
| Facilitated diffusion | The passive movement of a substance across a plasma membrane from an area of higher concentration to an area of lower concentration utilizing specialized carrier proteins. |
| Facultative anaerobe | An organism which is capable of producing energy through aerobic respiration and then switching back to anaerobic respiration depending on the amounts of oxygen and fermentable material in the environment. |
| Filtration | The process of separating suspended particles from the fluid through a porous material in which the fluid can pass while the suspended particles are retained. |
| Gene | A site on a chromosone that provides information for a certain cell function. A specific segment of DNA that contains the necessary code to make a protein or RNA molecule. |
| Genome | The complete set of chromosones and genes in an organism. |
| Halophiles | A microbe whose growth is either stimulated by salt or requires a high concentration of salt for growth. |
| Helicase | A prokaryote enzyme that uses the hydrolysis of atp to unwind the dna helix at the replication fork, to allow the resulting single strands to be copied. |
| Heterotroph | An organism that relies upon organic compounds for its carbon and energy needs. |
| Hfr cell | A bacterial cell that possesses the F factor integrated into the bacterial genome, hence, when it conjugates with another bacterium, it attempts to transfer a copy of the F |
| Hfr cell (cont'd) | factor as well as a portion of or the entire chromosome to the recipient bacterium. |
| Histone | Proteins associated with eukaryotic DNA. These simple proteins serve as winding spools to compact and condense the chromosones. |
| Icosahedral | A regular geometric figure having 20 surfaces that meet to form 12 corners. Some virions have capsids that resemble icosahedral crystals. |
| Induced mutation | Any alteration in DNA that occurs as a consequence of exposure to chemical or physical mutagens. |
| Intron | The segments on split genes of eukaryotes that do not code for polypeptide. They can have regulatory functions. |
| Lag phase | The early phase of population growth during which no signs of growth occur. |
| Lyophilization | A method for preserving microorganisms (and other substances) by freezing and then drying them directly from the frozen state. |
| Lysogeny | The indefinite persistence of bacteriophage DNA in a host without bringing about the production of virions. |
| Macronutrient | A chemical substance required in large quantities (phosphate, for example). |
| Micronutrient | A chemical substance required in small quantities (trace metals. |
| Mesophile | Microorganisms that grow at intermediate temperatures. |
| Missense mutation | A mutation in which a change in the DNA sequence results in a different amino acid being incorporated into a protein, with varying results. |
| mRNA (messenger) | A single stranded transcript that is a copy of the DNA template that corresponds to a gene. |
| rRNA (ribosomal) | A single stranded transcript that is a copy of part of the DNA template. |
| tRNA (transfer) | A transcript of DNA that specializes in converting RNA language into protein language. |
| Mutation | Change of genetic material inside the cell. |
| Mutualistic | Organisms living in an obligatory but mutually beneficial relationship. |
| Nonsense mutation | A form of point mutation resulting in a nonsense codon that does not code for an amino acid and leads to a protein product that is early truncated. |
| Nucleotide | The basic structural unit of DNA and RNA - phosphate, sugar and a nitrogenous base (adenine, guanine, thymine(in DNA) and cytosine) (adenine, guanine, uracil and cytosine in RNA) |
| Okazaki fragments | In replication of DNA, a segment formed on the lagging strand in which biosynthesis is conducted in a discontinuous manner dictated by the 5' > 3' DNA polymerase orientation. |
| Oncogenic | A naturally occurring type of gene that when activated, can transform a normal cell into a cancer cell. |
| Operon | A genetic operational unit that regulates metabolism by controlling mRNA production. In sequence, the unit consists of a regulatory gene, inducer or repressor control sites and structural genes. |
| Osmosis | The diffusion of water across a selectively permeable membrane in the direction of lower water concentration. |
| Parasitic | Description used in reference to an organism that lives within a host organism from which it gets its nutrients and protection. The parasite in turn produces some level of harm to the host organism. |
| Passive transport | Nutrient transport method that follows basic physical laws and does not require direct energy input from the cell. |
| Pasteurization | Heat treatment of perishable fluids such as milk, fruit juices or wine to destroy heat-sensitive vegetative cells, followed by rapid chilling to inhibit growth of survivors and germination of spores. It prevents infection and spoilage. |
| Phage | A bacteriophage - a virus that specifically parasitizes bacteria. |
| Phototroph | Microbes that use photosynthesis to feed. |
| Plaque | The clear zone of lysed cells in tissue culture. |
| Point mutation | A change that involves the loss, substitution, or addition of one or a few nucleotides. |
| Polymerase | An enzyme that produces polymers through catalyzing bond formation between building blocks. |
| Prions | A cytopathic protein associated with the slow-virus spongiform encephalopathies of humans and animals. |
| Promoter | Part of an operon sequence. The DNA segment that is recognized by RNA polymerase as the starting site for transcription. |
| Psychrophile | A microorganism that thrives at low temperatur (0* - 20* C) with a temperature optimum of 0* - 15* C. |
| Repressible operon | An operon that under normal circumstances is transcribed The build up of the operon's amino acid product causes transcription of the operon to stop. |
| Reverse transcriptase (RT) | The enzyme possed by retroviruses that carries out the reversion of RNA to DNA - a form of reverse transcription. |
| Rolling circle method | An intermediate stage in viral replication of circular DNA into linear DNA. |
| Sanitization | To clean inanimate objects using soap and degerming agents so that they are safe and free of high level of microorganisms. |
| Saprobes | A microbe that decomposes organic remains from dead organisms. Also known as a saprophyte or saprotroph. |
| Satellite virus | A minute infectious agent which lacks independent metabolism and is able to replicate only within a living host cell; consists of nucleic acid (nucleoid)—DNA or RNA (but not both)—and a protein shell (capsid), which contains and protects the nucleic acid |
| Semiconservative | In DNA replication, the synthesis of paired daughter strands, each retaining a parent strand template. |
| Silent mutation | A mutation that results in the nucleotide change in both the DNA and mRNA but the the amino acid and protein. This happens because of the degeneration of the genetic code. |
| Stationary phase | Survival mode in which cells either stop growing or grow very slowly. |
| Sterilization | Any process that completely removes or destroys all viable microorganisms, including viruses, from an object or habitat. Material is then considered sterile. |
| Superoxide dismutase | A toxic derivative of oxygen. |
| Surfactants | A surface-active agent that forms a water-soluble interface. ex: detergents, wetting agents, dispersing agents and surface tension depressants |
| TDP (Thermal Death Point) | The lowest temperature that achieves sterilization in a broth culture upon a 10 minute exposure. |
| TDT (Thermal Death Time) | The least time required to kill all cells of a culture at a specified temperature. |
| Template | The strand in a double-stranded DNA molecule that is used as a model to synthesize a complementary strand of DNA or RNA during replication or transcription. |
| Thermophile | A microorganism that thrives at a temperature of 50*C or higher. |
| Transcription | mRNA synthesis - the process by which a strand of RNA is produced against a DNA template. |
| Turbidity | Cloudy appearance of nutrient solution in a test tube due to growth of microbe population. |
| Viroids | An infectious agent unlike the virion. It lacks a capsid and consists of a closed circular RNA molecule. Although viroids are mostly plant pathogens, it is possible that there are animal versions of this as well. |
| Facultative | Capable of functioning under varying environmental conditions. Used of certain organisms, such as bacteria that can live with or without oxygen. It's adaptive vs. obligate which is not. |
| Obligate | Able to exist or survive only in a particular environment or by assuming a particular role. It is not adaptive. |
| Triplet (codon) | A specific sequence of three nucleotides in mRNA (or the sense strand of DNA)that constitutes the genetic code for a particular amino acid. |
| Transposon | A DNA segment with an insertion sequence at each end, enabling it to migrate to another plasmid, to the bacterial chromosome or to a bacteriorphage. |
| Tyndallization | Intermittent sterilization designed to destroy spores indirectly. A preparation is exposed to flowing steam for an hour. |
| Tyndallization (con't.) | The mineral is allowed to incubate to permit spore germination. The resulting vegetative cells are then destroyed by repeated steaming and incubation. |
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