BMSC 210 Final Exam Questions and All
Solved Correctly.
Mutation - Answer Heritable change in DNA sequence that can lead to a change in phenotype
Phenotype - Answer observable properties of an organism
Mutant - Answer a strain of any cell or virus differing from parental strain genotype
Genotype - Answer nucleotide sequence of genome
Wild-type Strain - Answer Typically refers to stain isolated from nature
Selectable Mutations - Answer -those that give the mutant a growth advantage under certain
conditions
-useful in genetic research
Nonselectable mutations - Answer -those that usually have no advantage that can be utilized
to allow their growth and not the parents
-detecting such mutations requires examining a large number of colonies and looking for
differences (screening)
Replica Plating - Answer -useful for identifying cells with a nutritional requirement for growth
(auxotroph)
Induced Mutations - Answer -those made environmentally or deliberately
-can result from exposure to natural radiation or oxygen radicals
-stimulated by factors above and beyond the "background rate"
Spontaneous Mutations - Answer those that occur without external interventions =
background level of DNA changes
Point Mutation - Answer -mutations that change only one base pair
Point Mutation : Silent Mutation - Answer -does not affect amino acid sequence
-"wobble"
,Point Mutation : Missense Mutation - Answer -amino acid changed
-polypeptide altered
Point Mutation : Nonsense Mutation - Answer -codon becomes stop codon
-polypeptide is incomplete
Frameshift Mutation - Answer -deletions or insertion that result in a shift in the reading frame
-often results in complete loss of gene function
Reversion - Answer -alteration in DNA that reverses the effects of a prior mutation
-reverts it back to a wild type
Revertant - Answer -strain in which original phenotype is restored
Same-site Revertant - Answer mutation is at the same site as orignal mutation
Second-site Revertant - Answer -mutation is at a different site in the DNA
-suppressor
Suppressor - Answer -an additional second mutation that compensates for the effect of the
original mutation
-"canceling each other out"
For most microorganisms, error in DNA replications occurs at a frequency of - Answer 10^-6 to
10^-7 per kb
DNA viruses have an error rate that is ________ times greater than microogranisms - Answer
100-1000
The mutation rate in RNA genomes is ______ than in DNA genomes - Answer 1000-fold higher
Some RNA polymerases have ______ - Answer proofreading capabilities
RNA repair mechanisms similar to DNA repair mechanisms _____ - Answer do not exist
, The Ames Test - Answer -makes practical use of bacterial mutations to detect for potentially
hazardous chemicals
-looks for an increase in mutations of bacteria in the presence of suspected mutagen
-a wide variety of chemicals have be screened for toxicity and carinogenicity
Mutagens - Answer chemical, physical, or biological agents that increase mutation rates
Classes of Chemical Mutagnes - Answer 1. Nucleotide Base Analogs: resemble nucleotides
"looks like a regular base but its different"
2. Chemical mutagens that induce chemical modification
3. Chemical Mutagens that cause frameshift mutations
Nonionizing - Answer -ie UV radiation
-purines and pyrimidines strongly absorb UV
-pyrimidine dimer is one effect of UV radiation
Ionizing - Answer - X-rays, Cosmic Rays, Gamma Rays
-ionize water and produce free radicals
-free radicals damage macromolecules in the cell
DNA Repair System: Direct Reversal - Answer mutated base is still recognizable and can be
repaired without referring to other strand
DNA Repair System: Repair of Single-Strand Damage - Answer damaged DNA is removed and
repaired using opposite strand as template
DNA Repair System: Repair of Double-Strand Damage - Answer -a break in the DNA
-requires more error-prone repair mechanism
When DNA damage is large scale: - Answer -the cell may use a different type of repair system
(ie when damage interferes with DNA replication)
-mechanism is called the SOS regulatory system and translesion synthesis
SOS regulator system - Answer -this system is more error-prone
-allows replication to proceed and cell to replicate, but errors are more likely to happen
-enzymes up the chromosomes back together
Solved Correctly.
Mutation - Answer Heritable change in DNA sequence that can lead to a change in phenotype
Phenotype - Answer observable properties of an organism
Mutant - Answer a strain of any cell or virus differing from parental strain genotype
Genotype - Answer nucleotide sequence of genome
Wild-type Strain - Answer Typically refers to stain isolated from nature
Selectable Mutations - Answer -those that give the mutant a growth advantage under certain
conditions
-useful in genetic research
Nonselectable mutations - Answer -those that usually have no advantage that can be utilized
to allow their growth and not the parents
-detecting such mutations requires examining a large number of colonies and looking for
differences (screening)
Replica Plating - Answer -useful for identifying cells with a nutritional requirement for growth
(auxotroph)
Induced Mutations - Answer -those made environmentally or deliberately
-can result from exposure to natural radiation or oxygen radicals
-stimulated by factors above and beyond the "background rate"
Spontaneous Mutations - Answer those that occur without external interventions =
background level of DNA changes
Point Mutation - Answer -mutations that change only one base pair
Point Mutation : Silent Mutation - Answer -does not affect amino acid sequence
-"wobble"
,Point Mutation : Missense Mutation - Answer -amino acid changed
-polypeptide altered
Point Mutation : Nonsense Mutation - Answer -codon becomes stop codon
-polypeptide is incomplete
Frameshift Mutation - Answer -deletions or insertion that result in a shift in the reading frame
-often results in complete loss of gene function
Reversion - Answer -alteration in DNA that reverses the effects of a prior mutation
-reverts it back to a wild type
Revertant - Answer -strain in which original phenotype is restored
Same-site Revertant - Answer mutation is at the same site as orignal mutation
Second-site Revertant - Answer -mutation is at a different site in the DNA
-suppressor
Suppressor - Answer -an additional second mutation that compensates for the effect of the
original mutation
-"canceling each other out"
For most microorganisms, error in DNA replications occurs at a frequency of - Answer 10^-6 to
10^-7 per kb
DNA viruses have an error rate that is ________ times greater than microogranisms - Answer
100-1000
The mutation rate in RNA genomes is ______ than in DNA genomes - Answer 1000-fold higher
Some RNA polymerases have ______ - Answer proofreading capabilities
RNA repair mechanisms similar to DNA repair mechanisms _____ - Answer do not exist
, The Ames Test - Answer -makes practical use of bacterial mutations to detect for potentially
hazardous chemicals
-looks for an increase in mutations of bacteria in the presence of suspected mutagen
-a wide variety of chemicals have be screened for toxicity and carinogenicity
Mutagens - Answer chemical, physical, or biological agents that increase mutation rates
Classes of Chemical Mutagnes - Answer 1. Nucleotide Base Analogs: resemble nucleotides
"looks like a regular base but its different"
2. Chemical mutagens that induce chemical modification
3. Chemical Mutagens that cause frameshift mutations
Nonionizing - Answer -ie UV radiation
-purines and pyrimidines strongly absorb UV
-pyrimidine dimer is one effect of UV radiation
Ionizing - Answer - X-rays, Cosmic Rays, Gamma Rays
-ionize water and produce free radicals
-free radicals damage macromolecules in the cell
DNA Repair System: Direct Reversal - Answer mutated base is still recognizable and can be
repaired without referring to other strand
DNA Repair System: Repair of Single-Strand Damage - Answer damaged DNA is removed and
repaired using opposite strand as template
DNA Repair System: Repair of Double-Strand Damage - Answer -a break in the DNA
-requires more error-prone repair mechanism
When DNA damage is large scale: - Answer -the cell may use a different type of repair system
(ie when damage interferes with DNA replication)
-mechanism is called the SOS regulatory system and translesion synthesis
SOS regulator system - Answer -this system is more error-prone
-allows replication to proceed and cell to replicate, but errors are more likely to happen
-enzymes up the chromosomes back together
