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105 Cards in this Set

  • Front
  • Back
actual changes i the chemical composition of DNA
genetic mutation
_________ provide the basis of genetic studies
heritable component of the phenotype that confers an advantage in survival and reproductive success. Process by which organisms adapt to the current environmental conditions
mutation that occurs spontaneously, that is, they arise independently of any external force
spontaneous mutation
Test that demonstrated spontaneous mutations are the source of phage resistant bacteria rather than adaptation.
Luria-Delbruck Fluctuation Test
statistical test developed by Luria and Delbruck to determine whether bacterial mutations arise spontaneously or are produced in response to selective agents
fluctuation test
_______ and ______
s work suggests that the bacterial cells' genetic machinery can respond to its environment by producing adaptive mutations
Cairn and Hall
all mutations are described as either ______ or ______
spontaneous or induced
mutations that happen naturally, no specific agents are associated with their occurence and they are generally assumed to be random changes in the nucleotide sequence
spontaneous mutation
mutations that result from the influence of any artificial factor
induced mutations
radiation from mineral sources and UV radiation to which most organisms are exposed, may be factors that cause ________ mutations
t/f mutations arising in somatic cells are NOT transmitted to future generations
mutations in ______ are of greater significance than somatic mutations b/c they are transmitted to offspring as part of the germ line
gametes (gametic mutations)
gametic mutation that will be expressed phenotypically in the first generation
Dominant autosomal mutation
gametic mutation arising in the gametes of a homogametic female that may be expressed in hemizygous male offspring
X linked recessive mutations
this type of mutation may go unnoticed for many generations until the resultant allele when a chance mating brings 2 copies of it together in the homozygous condition
autosomal recessive mutation
most easily observed mutations are those affecting a-
morphological trait
t/f Mendels pea characters and genetic variations in the study of Drosophila are results of changes in the morphology of an organism
mutations that aren't always visible, but can have a more general effect on the well being and survival of the affected individ'l
nutritional/biochemical mutations
mutations that affect behavior patterns of an organism
behavior mutations
mutation that may affect the regulation of genes, can disrupt normal regulatory processes and permanently activate or inactivate a gene
regulatory mutations
any mutation that may interrupt a process that is essential to the survival of the organism
lethal mutation
Tay Sachs and Huntington disease are good examples of what type of mutation in humans
lethal, but at different pts in the life cycle
mutation that is present in the genome of an organism, but is expressed and can be detected only under certain conditions
conditional mutations
temperature sensitive mutations acting at certain permissive temps, where a mutatnt gene product will function normally, only to lose its functional capability at a restrictive temperature is an example of what type of mutation
micro organisms that are nutrional wild types (requiring only minimal medium) are called-
mutant microorganisms that require a specific supplement to the minimal medium are called-
two techniques used in the identification of mutations in Drosophila
ClB and attached-X procedures
technique to identify the mutation in Drosophila where a wild type male is treated with a mutagenic agent (IE X ray) and mated to untreated ClB females
ClB detection
to determine the mutational basis for any human characteristic or disorder, geneticists must first analyze a ________ that traces the family history as far back as possible
most famous case of X-linked mutation in humas is that of-
any of several X-linked genetic disorders, symptomatic chiefly in males, in which excessive bleeding occurs owing to the absence or abnormality of a clotting factor in the blood.
t/f the spontaneous mutation rate vaires greatly among organisms
t/f even within the same species, the spontaneous mutation rate varies from gene to gene
would a bacteria gene or a human gene have a higher rate of spontaneous mutation-
Of or relating to a mutation that changes a codon for one amino acid into a codon for a different amino acid.
A mutation that involves a single nucleotide and may consist of loss of a nucleotide, substitution of one nucleotide for another, or the insertion of an additional nucleotide
point mutation
a nucleotide subsitution in which a pyrimidine replaces a pyramidine or a purine replaces a purine
nucleotide substitution in with a purine and a pyrimidine are interchanged
A mutation in a DNA chain that occurs when the number of nucleotides inserted or deleted is not a multiple of three, so that every codon beyond the point of insertion or deletion is read incorrectly during translation
frameshift mutation
Chemical isomerism characterized by relatively easy interconversion of isomeric forms in equilibrium
Because such a shift changes the bonding structure of the mx, Watson and Crick suggested that _____________ could result in base pair changes or mutations
tautomeric shifts
what type of mutation is the end result of a tautomeric shift-
point mutation
chemical compound that has a similar structure and similar chemical properties to those of another compound, but differs from it by a single element or group
a derivative of uracil, behaves as a thymine analog and is halogenated at the number 5 position of the pyrimidine ring
mustard gas is an example of a _____________, which donates an alkyl groups such as CH3 or CH3CH2 to amino or keto groups in nucleiotides resulting in a point mutation
alkylating agent
mustard gas, ethylmethane sulfonate (EMS), and 6-ethyl guanine are all examples of-
alkylating agents
chemical mutagens known as _________ cause frameshift mutations
acridine dyes
Proflavin and acridine orange are examples of-
acridine dyes (these are also alkylating agents)
sites of the spontaneous loss of one of the nitrogenous bases, most frequently guanine or adenine, ctreated by the 'breaking' of the glycosidic bond of the purine ring in an intact DNA molecule
apurinic sites (AP sites)
to remove the amino group from (a compound
all energy on the earth consists of a series of electromagnetic components of varying wavelength referred to as-
electromagnetic spectrum
purines and pyrimidines absorb UV radiation at a wavelength of ~ _____
260 nm
T/F in a study involving Drosophila eggs, it was discovered that UV radiation is NOT mutagenic
FALSE, UV radiation IS mutagenic
the major effect of UV radiation is on ___________, particularly b/t 2 thymine residues, that distort the DNA conformation and inhibit normal replication
pyrimidine dimers
t/f X rays, gamma rays, and cosmic rays have SHORTER wavelengths that UV radiation, and are therfore more energetic
rays that are strong enough to penetrate deeply into tissues, causing ionization of the molecules encountered along the way, are mutagenic
ionizing radiation
who established in the 1920s that ionizing radiation is mutagenic
Muller and Stadler
reactions of ionizing radiation can directly or indirectly affect the genetic material, altering the purines and pyrimidies in DNA and resulting in ________ mutations
theory proposed by Crowther and Dessauer proposing that there are one or more sites w/i cells and a single event of irradiation at one site will bring about a damaging effect or mutation
target theory
which human blood type would result ina a situation in which glycosyltransferase activity was lacking, and a failure to modify the H substance occured
blood type O
blood type O is a result of what type of mutation-
frameshift mutation that causes early termination, resulting in a nonfuntional product
t/f a frameshift mutation is more life threatening than a substitution mutation
DMD, the more severe form of muscular dystrophy is likely caused by a __________ mutation
BMD, the less severe form of muscular dystrophy is likely caused by a _________ mutation
mutant genes characterized by an expansion of a simple __________________, usually from fewer than 15 copies in normal individuals to a large number in affected individuals
trinucleotide repeat sequence
Fragile X Syndrome, Myotonic Dystrophy, and Huntington disease are all caused by _____________ in DNA sequences
trinucloetide repeat sequence
the idea of trinucleotide repeat sequences becoming larger in subsequent generations is an example of-
genetic anticipation
individuals with several hundred to several thousand copies of the trinucleotide sequence CGG have what syndrome
fragile X syndrome
t/f an individual with 5-37 copies of the trinucleotide CTG will not be affected by Myostonic dystrophy
TRUE, that is a normal amount of repeats
CAG trinucleotide repeats greater than 35 times results in what disease
Huntington disease
a test that uses any o fseveral strains of the bacterium Salmonella typhimurium that were selected for sensitivity and specificity for mutagenesis
Ames test
reversal of UV damage in prokaryotes based on the UV induced damage to E.coli seen to be partially reversied if following irradiation, the cells were exposed briefly to light in the blue range of the visible spectrum
photoreactivation repair
photoreactivation is dependent on the __________ enzyme that cleaves the bonds b/t thymine dimers, thus reversing the effect of UV radiation in DNA
photoreactivation enzyme (PRE)
(ONLY in bacteria)
this is a reversal of UV damage in both prokaryotes and eukaryotes that involves 3 basic steps, in general known as the 'cut and paste' system
excision repair
1968 James Cleaver showed that cells from XP patients were deficient in _____________ (synthesis other than that occuring during chromosome replication), which is elicited in normal cells by UV radiation.
unscheduled DNA synthesis
rare genetic disorder that predisposes individuals to severe skin abnormalities, they have lost their ability to undergo NER
seroderma pigmentosum (XP)
t/f ppl afflicted w/ XP are deficient excision repair
what 2 syndromes are caused by a defect in the human NER pathways?
1) XP
2) Cockayne syndrome (CS)
molecular mechanism for correcting erros in replication, transcription, or translation. Also known as editing
process of excision repair during which one or more unpaired bases are excised, followed by the synthesis of a new segment, using the complementary strand as a template
mismatch repair
system of DNA repair that responds after damaged DNA has escaped repair and failed to be completely replicated.
postreplication repair
induction of enzymes to repair damaged DNA in E. coli. involves activation of an enzyme that cleaves a repressor, activating a series of genes involved in DNA repair
SOS response
group of polymerases involved in the SOS response that have the capacity to respond to the 'crisis' and allow replication to continue in spite of the lesion
translesional polymerases
2 pioneers in the investigation of DNA repair
Hanawalt, Flanders
a specialized form of DNA repair, the ______________ pathway, is activated and is responsible for ultimately reannealing the 2 DNA segments
double strand break repair (DSB repair)
pathway involved in dbl strand break repair is referred to as ________________, because damaged DNA is actually recombined and replaced w/ homologous undamaged DNA, late S/G2 phase
homologous recombinational repair
pathway of dbl strand break repair in which 2 different protein complexes are involved in nonhomologous repair
end joining/ nonhomologous recombinational repair
experimental process in which researchers introduce a designed mutation at a prescribed site w/i a gene of interest
site directed mutagenesis
_______ won a Nobel prize in 1993 for his work with site directed mutagenesis
process of insertion into the genome a replacement of the comparable gene of the organism from whit it origniated
gene knockout
a cloned normal gene is inactivated by the insertion of a marker. the altered gene is transferred to embryonic stem cells, where the altered gene will replace the normal gene. these cells are injected into a glastomere embryo, producing a mouse that is bred to yield mice that homozygous for the mutated gene
knockout mice
organism whose genome has been modified by the introduction of external DNA sequences into the germ line
transgenic organism
genetic units that can move or be 'transposed' within the genome
mobile DNA segment thats transposable to any o fa number of sites in the genome
IS element (insertion sequence)
insertion sequences contain _______________ of one another, that is- the final sequence at the 5' end of one strand is the same as the final sequence at the 5' end of the other strand, except the sequences run in opposite directions
inverted terminal repeats (ITRs)
DNA segment that translocates to other sites in the genome, essentially independent of sequence homology- usually such elements are short, inverted repeats of 20 to 40 bps at each end. insertion into a structural gene can produce a mutant phenotype.
transposable element (Tn)
researcher who determined that Ds and Ac genes are mobile controlling elements in Maize plants
nucleotides b/t the start and stop codons that encode amino acids
open reading frame (ORF)
1975 Hogness and colleagues identified a class of genes in Drosophila that they designated as ________, these are genes that transcribe copious amounts of RNA
a condition causing sterility, elevated mutation rate, and chrom rearrangment in the offspring of crosses b/t certain strains of fruit flies
hybrid dysgenesis
hybrid dysgenesis is caused by high rates of _________ transoposition in the germ line, a phenomenon wherin the mobile DNA elements insert themselves into or near genes, therby causing mutations
P element
sequence found in the copia transposon, these are found in other transposons in other organisms but are not universal
direct terminal repaet (DTR)
repetitive sequences found in the genomes of higher organisms, such as the 300 bp Alu sequence
short interpsersed elements (SINEs)
repetitive sequences found in the genome of higher org's, such as the 6 kb L1 sequences found in primate genomes
Long interspersed elements (LINEs)