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Biology HESI

HESI Standardized Test

aerobe a microorganism that grows in the presence of oxygen
amino acid any of 20 basic building blocks of proteins.
anaerobe a microorganism that grows in the absence of oxygen
antibiotic resistance the ability of a microorganism to produce a protein to disable an antibiotic or prevents transport of the antibiotic into the cell
antibiotic a class of natural and synthetic compounds that inhibit the growth or kill other microorganisms
Antibody. An immunoglobulin protein produced by B- lymphocytes of the immune system that binds to a specific antigen molecule.
Anticodon. A nucleotide base triplet in a transfer RNA molecule that pairs with a complementary base triplet, or codon, in a messenger RNA molecule.
Antigen. Any foreign substance, such as a virus, bacterium, or protein, that elicits an immune response by stimulating the production of antibodies.
Antigenic determinant. A surface feature of a microorganism or macromolecule, such as a glycoprotein, that elicits an immune response.
Antimicrobial agent. Any chemical or biological agent that harms the growth of microorganisms.
Asexual reproduction. Nonsexual means of reproduction which can include grafting and budding.
Autosome A chromosome that is not involved in sex de- termination.
Bacillus. A rod-shaped bacterium.
Backcross. Crossing an organism with one of its parent organisms.
Bacteriocide. A class of antibiotics that kills bacterial cells.
Bacteriophage (phage or phage particle). A virus that infects bacteria. Altered forms are used as vectors for cloning DNA.
Bacterioostat. A class of antibiotics that prevents growth of bacterial cells.
Bacterium. A single-celled, microscopic prokaryotic organism: a single cell organism without a distinct nucleus.
Base pair (bp). A pair of complementary nitrogenous bases in a DNA molecule--adeninethymine and guanine-cytosine. Also, the unit of measurement for DNA sequences.
Biologics. Agents, such as vaccines, that give immunity to diseases or harmful biotic stresses.
Catalyst. A substance that promotes a chemical reaction by lowering the activation energy of a chemical reaction, but which itself remains unaltered at the end of the reaction.
Catalytic antibody (abzyme). An antibody selected for its ability to catalyze a chemical reaction by binding to and stabilizing the transition state intermediate.
Catalytic RNA (ribozyme). A natural or synthetic RNA molecule that cuts an RNA substrate.
Cation. A positively charged ion.
Centers of origin. Usually the location in the world where the oldest cultivation of a particular crop has been identified.
Centromere. The central portion of the chromosome to which the spindle fibers attach during mitotic and meiotic division.
Chemotherapy. A treatment for cancers that involves administering chemicals toxic to malignant cells.
Chloramphenicol. An antibiotic that interferes with protein synthesis.
Chromatid. Each of the two daughter strands of a duplicated chromosome joined at the centromere during mitosis and meiosis.
Codon. A group of three nucleotides that specifies addition of one of the 20 amino acids during translation of an mRNA into a polypeptide. Strings of codons form genes and strings of genes form chromosomes.
Coenzyme a vitamin, that binds to an enzyme and is required for its catalytic activity.
Colony. A group of identical cells (clones) derived from a single progenitor cell.
Conjugation. The joining of two bacteria cells when genetic material is transferred from one
bacterium to another.
Cross-hybridization. The hydrogen bonding of a single- stranded DNA sequence that is partially but not entirely complementary to a single-stranded substrate. Often, this involves hybridizing a DNA probe for a specific DNA sequence to the homologous sequences of different spe
Crossing-over. The exchange of DNA sequences between chromatids of homologous chromosomes during meiosis.
Cross-pollination. Fertilization of a plant from a plant with a different genetic makeup.
Culture. A particular kind of organism growing in a laboratory medium.
Dalton. A unit of measurement equal to the mass of a hydrogen atom, 1.67 x 10E-24 gram/L (Avogadro's number).
Death phase. The final growth phase, during which nutrients have been depleted and cell number decreases.
Denature. To induce structural alterations that disrupt the biological activity of a molecule. Often refers to breaking hydrogen bonds between base pairs in double-stranded nucleic acid molecules to produce in single-stranded polynucleotides or altering the second
Density gradient centrifugation High-speed centrifugation in which molecules "float" at a point where their density equals that in a gradient of cesium chloride or sucrose.
Dideoxynucleotide (didN). A deoxynucleotide that lacks a 3' hydroxyl group, and is thus unable to form a 3'-5' phosphodiester bond necessary for chain elongation.Dideoxynucleotides are used in DNA sequencing and the treatment of viral diseases
carcinogen a substance that induces cancer
carcinoma a malignant tumor derived from epithelial tissue, which forms the skin and outer layers of internal organs
Diploid cell. A cell which contains two copies of each chromosome.
DNA (Deoxyribonucleic acid). An organic acid and polymer composed of four nitrogenous bases--adenine, thymine, cytosine, and guanine linked via intervening units of phosphate and the pentose sugar deoxyribose. DNA is the genetic material of most organisms and usually exists as a doub
DNA sequencing. Procedures for determining the nucleotide sequence of a DNA fragment.
Dominant gene. A gene whose phenotype is when it is present in a single copy.
Dominant(-acting) oncogene. A gene that stimulates cell proliferation and contributes to oncogenesis when present in a single copy.
Dominant. An allele is said to be dominant if it expresses its phenotype even in the presence of a recessive allele.
Dormancy. A period in which a plant does not grow, awaiting necessary environmental conditions such as temperature, moisture, nutrient availability.
Double helix. Describes the coiling of the antiparallel strands of the DNA molecule, resembling a spiral staircase in which the paired bases form the steps and the sugar-phosphate backbones form the rails.
Double-stranded complementary DNA (dscDNA). A duplex DNA molecule copied from a cDNA template.
Ecology. The study of the interactions of organisms with their environment and with each other.
Ecosystem. The organisms in a plant population and the biotic and abiotic factors which impact on them. See abiotic factors; Biotic factors.
Electrophoresis. The technique of separating charged molecules in a matrix to which is applied an electrical field.
Electroporation. A method for transforrning DNA, especially useful for plant cells, in which high voltage pulses of electricity are used to open pores in cell membranes, through which foreign DNA can pass.
Endophyte. An organism that lives inside another.
Enzymes. Proteins that control the various steps in all chemical reactions.
Eukaryote. An organism whose cells possess a nucleus and other membrane-bound vesicles, including all members of the protist, fungi, plant and animal kingdoms; and excluding viruses, bacteria, and blue-green algae.
Evolution. The long-term process through which a population of organisms accumulates genetic changes that enable its members to successfully adapt to environmental conditions and to better exploit food resources.
Flanking region. The DNA sequences extending on either side of a specific locus or gene.
Fungus. A microorganism that lacks chlorophyll.
Gene insertion. The addition of one or more copies of a normal gene into a defective chromosome.
Gene. A locus on a chromosome that encodes a specific protein or several related proteins. It is considered the functional unit of heredity.
Genetic engineering. The manipulation of an organism's genetic endowment by introducing or eliminating specific genes through modern molecular biology techniques. A broad definition of genetic engineering also includes selective breeding and other means of artificial selecti
Genetic marker. A gene or group of genes used to "mark" or track the action of microbes.
Genotype. The structure of DNA that determines the expression of a trait.
Genus. A category including closely related species. Interbreeding between organisms within the same category can occur.
Growth factor. A serum protein that stimulates cell division when it binds to its cell-surface receptor.
Haploid cell. A cell containing only one set, or half the usual (diploid) number, of chromosomes.
Hemophilia. An X-linked recessive genetic disease, caused by a mutation in the gene for clotting factor VIII (hemophilia A) or clotting factor IX (hemophilia B), which leads to abnormal blood clotting.
Homologous chromosomes. Chromosomes that have the same linear arrangement of genes-a pair of matching chromosomes in a diploid organism.
Homologous recombination. The exchange of DNA fragments between two DNA molecules or chromatids of paired chromosomes (during crossing over) at the site of identical nucleotide sequences.
Host. An organism that contains another organism.
Hydrogen bond. A relatively weak bond formed between y. a hydrogen atom (which is covalently bound to a nitrogen or oxygen atom) and a nitrogen or oxygen with an unshared electron pair
Hydrolysis. A reaction in which a molecule of water is added at the site of cleavage of a molecule to two products.
In situ. Refers to performing assays or manipulations with intact tissues.
In vivo. Refers to biological processes that take place within a living organism or cell.
Incomplete dominance. A condition where a heterozygous off- spring has a phenotype that is distinctly different from, and intermediate to, the parental phenotypes.
Insulin. A peptide hormone secreted by the islets of Langerhans of the pancreas that regulates the level of sugar in the blood.
Interferon. A family of small proteins that stimulate viral resistance in cells.
Lysis. The destruction of the cell membrane.
Malignant. Having the properties of cancerous growth.
Meiosis. The reduction division process by which haploid gametes and spores are formed, consisting of a single duplication of the genetic material followed by two mitotic divisions.
Messenger RNA (mRNA). The class of RNA molecules that copies the genetic information from DNA, in the nucleus, and carries it to ribosomes, in the cytoplasm, where it is translated into protein.
Metabolism. The biochemical processes that sustain a living cell or organism.
Mitosis. The replication of a cell to form two daughter cells with identical sets of chromosomes.
Molecular biology. The study of the biochemical and molecular interactions within living cells.
Mutagen. Any agent or process that can cause mutations.
Mutation. An alteration in DNA structure or sequence of a gene.
Natural selection. The differential survival and reproduction of organisms with genetic characteristics that enable them to better utilize environmental resources.
Nucleic acids. The two nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are made up of long chains of molecules called nucleotides. Nucleotide. A building block of DNA and RNA, consisting of a nitrogenous base, a five-carbon sugar, and a phosphate
Occupational Safety and Health Administration (OSHA). One of the U.S. agencies responsible for regulation of biotechnology. The major law under which the agency has regulatory powers is the Occupational Safety and Health Act.
Organelle. A cell structure that carries out a specialized function in the life of a cell.
Ovum. A female gamete.
Parasitism. The closest association of two or more dissimilar organisms where the association is harmful to at least one.
Pathogen. Organism which can cause disease in another organism.
Persistence. Ability of an organism to remain in a particular setting for a period of time after it is introduced.
Pesticide. A substance that kills harmful organisms (for example, an insecticide or fungicide).
Phenotype. The observable characteristics of an organism, the expression of gene alleles (genotype) as an observable physical or biochemical trait.
Phospholipid. A class of lipid molecules in which a phosphate group is linked to glycerol and two fatty acyl groups. A chief component of biological membranes.
Plaque. A clear spot on a lawn of bacteria or cultured cells where cells have been Iysed by viral infection.
Polymer. A molecule composed of repeated subunits.
Polypeptide (protein). A polymer composed of multiple amino acid units linked by peptide bonds.
Polysaccharide. A polymer composed of multiple units of monosaccharide (simple sugar).
Primary cell. A cell or cell line taken directly from a living organism, which is not immortalized.
Prokaryote. A bacterial cell lacking a true nucleus; its DNA is usually in one long strand.
Protease. An enzyme that cleaves peptide bonds that link amino acids in protein molecules.
Protein kinase. An enzyme that adds phosphate groups to a protein molecule at serine, threonine, or tyrosine residues.
Protein. A polymer of amino acids linked via peptide bonds and which may be composed of two or more polypeptide chains
Recessive gene. Characterized as having a phenotype expressed only when both copies of the gene are mutated or missing
Recombinant DNA. The process of cutting and recombining DNA fragments from different sources as a means to isolate genes or to alter their structure and function.
Recombinant. A cell that results from recombination of genes.
Retrovirus. A member of a class of RNA viruses that utilizes the enzyme reverse transcriptase to reverse copy its genome into a DNA intermediate, which integrates into the hostcell chromosome. Many naturally occurring cancers of vertebrate animals are caused by retr
Reverse genetics. Using linkage analysis and polymorphic markers to isolate a disease gene in the absence of a known metabolic defect, then using the DNA sequence of the cloned gene to predict the amino acid sequence of its encoded protein.
Ribosomal RNA (rRNA). The RNA component of the ribosome.
RNA (ribonucleic acid). An organic acid composed of repeating nucleotide units of adenine,bonds.
Sexual reproduction. The process where two cells (gametes) fuse to form one hybrid, fertilized cell.
Subunit vaccine. A vaccine composed of a purified antigenic determinant that is separated from the virulent organism.
Synapsis. The pairing of homologous chromosome pairs during prophase of the first
meiotic division, when crossing over occurs.
Taq polymerase. A heat-stable DNA polymerase isolated from the bacterium Therrnus aquaticus, used in PCR.
Telomere. The end of a chromosome.
Transcription. The process of creating a complementary RNA copy of DNA.
Vaccine. A preparation of dead or weakened pathogen, or of derived antigenic determinants, that is used to induce formation of antibodies or immunity against the pathogen.
Vector. An autonomously replicating DNA molecule into which foreign DNA fragments are inserted and then propagated in a host cell. Also living carriers of genetic material (such as pollen) from plant to plant, such as insects.
Virulence. The degree of ability of an organism to cause disease.
Virus. An infectious particle composed of a protein capsule and a nucleic acid core, which is dependent on a host organism for replication. A double-stranded DNA copy of an RNA virus genome that is integrated into the host chromosome during lysogenic infection.
Wild type. An organism as found in nature; the organism before it is genetically engineered.
X-linked disease. A genetic disease caused by a mutation on the X chromosome. In X-linked recessive conditions, a normal female "carrier" passes on the mutated X chromosome to an affected son.
Created by: troylford