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genetics > ch 19 gene mutation, dna repair, and recombination > Flashcards

ch 19 gene mutation, dna repair, and recombination Flashcards

1
Q

mutation

A

a permanent change in the genetic material that can be passed from cell to cell or if it occurs in reproductive cells, from parent to offspring

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2
Q

homologous recombination

A

the exchange of identical or similar dna segments between homologous chromosomes

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3
Q

point mutation

A

a change in a single base pair within dna

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4
Q

base substitution

A

a point mutation in which one base is substituted for another

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5
Q

transition

A

a point mutation involving a change of a pyrimidine to another pyrimidine or a purine to another purine

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6
Q

transversion

A

a point mutation in which a purine is interchanged with pyrimidine, or vice versa

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7
Q

silent mutation

A

a mutation that does not alter the amino acid sequence of the encoded polypeptide even though the base sequence has changed

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8
Q

missense mutation

A

a base substitution that leads to a change in the amino acid sequence of the encoded polypeptide

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9
Q

nonsense mutation

A

a mutation that involves a change from a normal codon to a stop codon

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10
Q

frameshift mutation

A

a mutation that involves the addition or deletion of a number of nucleotide not divisible by 3, which shifts the reading frame of the codons downstream from the mutation

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11
Q

neutral mutation

A

a mutation that has no detectable effect on the survival of the organism

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12
Q

up promoter mutation

A

a mutation in a promoter that increases the rate of transcription

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13
Q

down promoter mutation

A

a mutation in a promoter that decreases the rate of transcription

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14
Q

wild type

A

a relatively prevalent genotype in a natural population

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15
Q

mutant allele

A

an allele that has been created by altering a wild-type allele by mutation

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16
Q

reversion

A

(also called a reverse mutation) a mutation that changes a mutant allele back to a wild-type allele

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17
Q

deleterious mutation

A

a mutation that is detrimental with regard to its effect on phenotype

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18
Q

lethal mutation

A

a mutation that produces an allele that results in the death of a cell or an organism

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19
Q

beneficial mutation

A

a mutation that enhances the survival or reproductive success of an organism

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20
Q

conditional mutant

A

a mutant whose phenotype depends on the environmental conditions, such as a temperature-sensitive mutant

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21
Q

suppressor

A

(also called suppressor mutation) a mutation at a second site that suppresses the phenotypic effects of another mutation

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22
Q

intragenic supressor

A

a suppressor mutation that is within the same gene as the first mutation it suppresses

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23
Q

intergenic suppressor

A

a suppressor mutation that occurs in a different gene than the gene that contains the first mutation

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24
Q

breakpoint

A

a region where two chromosomes pieces break apart and rejoin with other chromosome pieces

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25
position effect
a change in phenotype that occurs when the location of a gene changes from one chromosomal site to a different one
26
germ line
refers to cells that give rise to gametes (eggs or sperm)
27
germ-line mutation
a mutation in a cell of the germ line
28
somatic mutation
a mutation in a somatic cell
29
genetic mosaic
an individual that has somatic regions that differ genotypically from one another
30
replica plating
a technique in which replicas of bacterial colonies are transferred to new growth plates
31
random mutation theory
according to this theory, mutations are random events–they can occur in any gene and do not require exposure of an organism to an environmental condition that causes specific types of mutations
32
hot spots
regions within a gene that are more likely to mutate than others
33
spontaneous mutation
a change in dna structure that results from natural biological or chemical processes
34
induced mutation
a change in dna structure caused by an environmental agent
35
depurination
the removal of a purine base from dna
36
apurinic site
a site in dna that is missing a purine base
37
deamination
the removal of an amino group from a molecule; for example, the removal of an amino group from cytosine produces uracil
38
tautoemeric shift
a temporary change in chemical structure, such as an alteration between keto and enol forms of the bases that are found in dna
39
tautomers
chemically similar forms of certain small molecules, such as bases, which can spontaneously interconvert
40
reactive oxygen species (ROS)
products of oxygen metabolism that are produced in all aerobic organism and that can, if they accumulate, damage cellular molecules, including dna, proteins, and lipids
41
oxidative stress
an imbalance between the production of reactive oxygen species and an organism's ability to break them down
42
oxidative dna damage
changes in dna structure that are caused by reactive oxygen species
43
trinucleotide repeat expansion (TNRE)
a type of mutation that involves an increase in the number of tandemly repeated trinucleotide sequences
44
anticipation
the phenomenon in which the severity of an inherited disease tends to get worse in subsequent generations
45
mutagen
an agent that can be altered the structure of dna, causing a mutation
46
nitrous acid
a type of chemical mutagen that deaminates bases, replacing amino groups with keto groups
47
nitrogen mustard
an alkylating agent that can cause mutations in dna
48
ethyl methanesulfonate (EMS)
a type of chemical mutagen that alkylates bases (ie attaches methyl or ethyl groups)
49
acridine dye
a type of chemical mutagen that intercalates between adjacent base pairs in dna and causes frameshift mutations
50
proflavin
an acridine dye
51
5-bromouracil (5BU)
a base analog that acts as a chemical mutagen
52
2-aminopurine
a base analog that acts as a chemical mutagen
53
thymine dimer
two adjacent thymine bases in a dna strand that have become covalently linked
54
mutation rate
the likelihood that a gene will be altered by a new mutation
55
mutation frequency
the number of mutant genes divided by the total number of copies of a gene within a population
56
ames test
a test using strains of a bacterium, salmonella typhimurium, to determine if a substance is a mutagen
57
photolyase
an enzyme found in bacteria, fungi, most plants, and some animals that can recognize and split thymine dimers, which returns the dna to its original condition
58
photoreactivation
a type of dna repair mechanism of thymine dimers that involves photolyase and requires light
59
alkyltransferase
an enzyme that can remove methyl or ethyl groups from guanine bases
60
base excision repair (BER)
a type of dna repair in which a modified base is removed from a dna strand; following base removal, a short region of the dna strand is removed and then resynthesized using the complementary strand as a template
61
dna n-glycosylase
an enzyme that can recognize an abnormal base and cleave the bond between it and the sugar in the dna backbone
62
ap endonuclease
a dna repair enzyme that recognizes a dna region that is missing a base and makes a cut in the dna backbone near the site
63
nucleotide excision repair (NER)
a dna repair system in which several nucleotides in the damaged strand are removed from the dna and the undamaged strand is used as a template to resynthesize a normal strand
64
base pair mismatch
a dna abnormality in which two bases opposite of each other in a double helix do not conform to the AT/GC rule; for example is A were opposite of C, that would be a mismatch
65
mismatch repair system
a dna repair system that recognizes mismatches and repairs the newly made daughter strand that contains the incorrect base
66
homologous recombination repair (HRR)
(also called homology-directed repair) mechanism for repairing double-strand breaks that occurs when the dna strands from a sister chromatid are used to repair a lesion in the other sister chromatid
67
nonhomologous end joining (NHEJ)
a repair mechanism for double strand breaks in which the ends of the dna are pieced back together
68
translesion synthesis (TLS)
the synthesis of dna over a template strand that harbors some type of dna damage; occurs via translesion-replicating polymerases
69
error-prone replication
a form of dna replication carried out by translesion-replicating polymerases that results in a high rate of mutation
70
sister chromatid exchange (SCE)
the phenomenon in which crossing over occurs between sister chromatids, which thereby exchange identical genetic material
71
genetic recombination
1. the process in which chromosomes are broken and then rejoined to form a novel genetic combination 2. the process in which alleles are assorted and passed to offspring in combinations that are different from those found in the parents
72
gene conversion
the phenomenon in which one allele is converted to the allele on the homologous chromosome due to recombination or dna repair
73
holliday model
a model to explain the molecular mechanism of homologous recombination
74
holliday junction
a site where an unresolved crossover has occurred between two homologous chromosomes
75
branch migration
the lateral movement of a holliday junction
76
heteroduplex
a region of double-stranded dna that contains one or more base mismatches
77
resolution
1. the last two steps of homologous recombination, in which the entangled dna strands become resolves into two separate chromosomes
78
double-strand break model
a model for homologous recombination in which the event that initiates recombination is a double-strand break in one of two homologous chromatids
79
dna gap repair synthesis
the synthesis of dna in a region where part of a dna strand has been previously removed, usually by an dna repair enzyme or by an enzyme involved in homologous recombination

genetics (20 decks)

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