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72 Cards in this Set

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