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72 Cards in this Set
- Front
- Back
operon
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A sequence of closely associated genes that includes both structural genes and regulatory sites that control transcription
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inducer
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A substance that binds to and inactivates a repressor protein
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transcription
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The synthesis of RNA from a DNA template
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prototroph
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A normal, nonmutant organism (also called wild type)
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heredity
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The transmission of genetic traits from an organism to its progeny
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enzyme induction
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A mechanism whereby the genes coding for enzymes needed to metabolize a particular nutrient are activated by the presence of that nutrient
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mutagen
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An agent that increases the rate of mutations
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dimer
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Two adjacent pyrimidines bonded together in a DNA strand, usually as a result of exposure to ultraviolet rays
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carcinogen
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A cancer-producing substance
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frameshift mutation
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Mutation resulting from the deletion or insertion of one or more bases
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nonsense codon
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(also called terminator codon) A set of three bases in a gene (or mRNA) that does not code for an amino acid
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locus
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The location of a gene on a chromosome
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light repair
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(also called photoreactivation) Repair of DNA dimers by a light-activated enzyme
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Okazaki fragment
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One of the short, discontinuous DNA segments formed on the lagging strand during DNA replication
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constitutive enzyme
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An enzyme that is synthesized continuously regardless of the nutrients available to the organism
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Ames test
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Test used to determine whether a particular substance is mutagenic, based on its ability to induce mutations in auxotrophic bacteria
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exonuclease
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An enzyme that removes segments of DNA
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transfer RNA (tRNA)
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Type of RNA that transfers amino acids from the cytoplasm to the robosomes for placement in a protein molecule
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exon
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The region of a tene (or mRNA) that coes for a protein in eukaryotic cells
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genetic code
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The one-to-one relationshiop between each codon and a specific amino acid
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mutation
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A permanent alteration in an organism's DNA
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terminator codon
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(also called nonsense codon or stop codon) A codon that signals the end of the information for a particular protein
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catabolite repression
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Process by which the presence of a preferred nutrient (often glucose) represses the genes coding for enzymes used to metabolize some alternative nutrient
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ligase
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An enzyme that joins together DNA segments
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acridine derivative
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A chemical mutagen that can be inserted between bases of the DNA double helix, causing frameshift mutations
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allele
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The form of a gene that occupies the same place (locus) on the DNA molecule as another form but may carry different information for a trait
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PCR (polymerase chain reaction)
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A technique that rapidly produces a billion or more identical copies of a DNA fragment without needing a cell
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lagging strand
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The new strand of DNA formed in short, discontinuous DNA segments during DNA replication
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base analog
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A chemical mutagen similar in molecular structure to one of the nitrogenous bases found in DNA that causes point mutations
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fluctuation test
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A test to determine that resistance to chemical substances occurs spontaneously rather than being induced
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induction
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The stimulation of a temperate phage (prophage) to excise itself from the host chromosome and initiate a lytic cycle of replication
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sense codon
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A set of three DNA (or RNA) bases that code for an amino acid
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insertion
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The addition of one or more bases to DNa, usually producing a frameshift mutation
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messenger RNA
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(mRNA)A type of RNA that carries the information from DNA to dictate the arrangement of amino acids in a protein
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respiratory system
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Blood system that moves oxygen from the atmosphere to the blood ahd removes carbon dioxide and other wastes from the blood
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translation
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The synthesis of protein from information in mRNA
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retrovirus
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An enveloped RNA virus that uses its own reverse transcriptase to transcribe its RNA into DNA in the cytoplasm of the host cell
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deletion
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The removal of one or more nitrogenous bases from DNA, usually producing a frameshift mutation
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replica plating
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A technique used to transfer colonies from one medium to another
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ringworm
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A highly contagious fungal skin disease that can cause ringlike lesions
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replication
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Process by which an organism or structure (especially a DNA molecule) duplicates itself
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structural gene
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A gene that carries information for the synthesis of a specific polypeptide
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attenuation
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(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
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repressor
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In an operon it is the protein that binds to the operator, thereby preventing transcription of adjacent genes
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auxotrophic mutant
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An organism that has lost the ability to synthesize one or more metabolically important enzymes through mutation, therefore requires special substances in its growth medium
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DNA Polymerase
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An enzyme that moves along behind each replication fork, synthesizing new DNA strands complementary to the original ones
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anticodon
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A three-base sequence in tRNA that is complementary to one of the mRNA codons, forming a link between each codon and the corresponding amino acid.
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genetics
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The science of heredity, including the structure and regulation of genes and how these genes are passed between generations
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semiconservative replication
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Replication in which a new DNA double helix is synthesized from one strand of parent DNA and one strand of new DNA
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enzyme repression
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Mechanism by which the presence of a particular metabolite represses the genes coding for enzymes used in its synthesis
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dark repair
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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
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leading strand
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The new strand of DNA formed as a continuous strand during DNA replication
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intron
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(also called intervening region) Region of a gene (or mRNA) in eukaryotic cells that does not code for a protein
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DNA replication
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Formation of new DNA molecules
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deaminating agent
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A chemical mutagen that can remove an amino group (-NH2) from a nitrogenous base, causing a point mutation
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phenotype
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The specific observable characteristics displayed by an organism
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inducible enzyme
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An enzyme coded for by a gene that is sometimes active and sometimes inactive
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genotype
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The genetic information contained in the DNA of an organism
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alkylating agent
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A chemical mutagen that can add alkyl groups (-CH3) to DNA bases, altering their shapes and causing errors in base pairing
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gene
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A linear sequence of DNA nucleotides that form a functional unit within a chromosome or plasmid
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antiparallel
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The opposite head-to-tail arrangement of the two strands in a DNA double helix
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replication form
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A site at which the two strands of the DNA double helix separate during replication and new complementary DNA strands form
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start codon
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The first codon in a molecule of mRNA which begins the sequence of amino acids in protein synthesis; in bacteria it always codes for methionine
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template
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DNA used as a pattern for the synthesis of a new nucleotide polymer in replication or transcription
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stop codon
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(also called terminator codon) The last codon to be translated in a molecule of mRNA,causing the ribosome to release from the mRNA
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regulator gene
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gene that controls the expression of structural genes of an operon through the synthesis of a repressor protein
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point mutation
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Mutation in which one base is substituted for another at a specific location in a gene
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regulatory site
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The promotor and operator regions of an operon
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induced mutation
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A mutation produced by agents called mutagen that increase the mutation rate
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spontaneous mutation
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A mutation that occurs in the absence of any agent known to cause changes in DNA; usually caused by errors during DNA replication
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repressor protein
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Substance produced by host cells that keeps a virus in an inactive state and prevents the infection of the cell by another phage
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radiation
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Light rays, such as X-rays and ultraviolet rays, that can act as mutagens
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