Mutation Flashcards
Definition: Mutant
Organism that is direct offspring of wild-type but is different
Definition: Strain
Organisms of the same species isolated from nature that have different properties (because it is no possible to know which the mutant)
Definition: Phenotype
All the observable properties of an organism
Definition: Genotype
The actual sequence of an organism’s DNA
Definition: Mutation
An heritable change in DNA sequence
Definition: Allele
Different forms of the same gene. Bacteria are haploid therefore it has one allele
Nomenclature: lac
lactose metabolism
Nomenclature: his
histidine biosynthesis
Nomenclature: dna
DNA synthesis
Nomenclature: pol
DNA polymerase
Nomenclature: uvr
UV repair
Nomenclature: rec
Recombination
Letters distinguish different genes that affect or function in the same process. Give an example.
lacZ, lacY, lacA ; hisA, hisB, hisC (all undercase should be italicized)
Protein products of genes are given the same name. (but it is not “italicized” and the first letter is capitalized) Give an example
RecA ; DnaA
What are the consequences of mutations?
- Some are harmless
- Some may cause a change in phenotype
- Some are bad
- Some are lethal
Bac Phenotypes: Prototroph and auxotroph. (based on growth on particular media)
An auxotroph can not make or lacks the ability to grow on a particular nutrient. [Ex. A mutant strain that has lost the ability to synthesize its own supply of tryptophan is a Trp auxotroph and is designated Trp]
Bac Phenotypes: Ability to utilize substrates (based on growth on particular media)
The ability to utilize a particular carbon and energy source can also be used as a phenotype. [Ex. A strain harboring a mutation rendering it unable to utilize the sugar galactose is galactose-, of Gal-]
Bac Phenotypes: Antibiotic resistance (based on growth on particular media)
The ability to grow in the presence of an antibiotic
Bac Phenotypes: Other markers (2 examples) (based on growth on particular media)
Colony morphology and resistance to phage.
Auxotrophic mutants can be isolated because?
They have mutations in genes whose products are required under certain conditions.
What are the conditions that DNA changes would be lethal?
- Temperature sensitive mutants
- Cold sensitive mutants
- Nonsense mutations
What are the two types of Temperature-sensitive mutation from DNA changes?
- Permissive temperature: the protein function
* Nonpermissive temperature: higher temperature
Lethal DNA mutation def: Temperature-sensitive mutants
Change an amino acid of the protein so that protein no longer function at high temperature but still function at lower temp
Lethal DNA mutation def: Cold sensitive mutants
Cells with proteins that fail to function at lower temperature. The mutation occurs in genes whose products must form a large complex (ex. Ribosome_
-At higher temp, the mutated protein can entered in the complex, but it will not be able to do so a lower temperature
Lethal DNA mutation def: Nonsense mutations
Mutation that change a codon in a gene to one of the three nonsense codons (UAA, UAG, or UGA)
-Translation of the gene doesn’t stop unless the cell has a “nonsense suppressor” tRNA
Resistance: Luria and Delbruck experiment demonstrates that in bacteria, genetic mutations arise in the absence of selection, rather than being a response to selection. What are the two types of hypothesis and their definitions
- Random mutations: If it is correct among of mutated will varied in all cultures, depending of when the mutation occur
- Direct change: If it is correct each bacterium will have same chance of becoming a mutant
T or F: Random mutations hypothesis is correct
True; If correct among the mutated will vary in all cultures, depending of when the mutation occur.
What are the two ways that could cause mutations?
- Environmental insults
2. Errors in DNA replication
Mutations are?
Permanent changes in the DNA sequence that are inherited
Depending upon the nature of the mutation, they can what?
Be expressed as abnormal proteins
Depending upon the function of the protein, mutations that affect that protein might what?
Result in an easily observable phenotypic change
Some mutations (phenotypes) only appear under what kind of conditions?
Only under certain conditions, such as exposure to a certain environmental agent or condition
Base Pair changes have 4 different type that can cause it. What are they?
- Transitions
- Transversions
- Missense mutations
4 Nonsense mutations
Base pair changes are one of the types of mutations. What are the other 4?
- Frameshift mutations
- Deletion mutations
- Inversion mutations
- Tandem duplications
Mispairing during the replication can what?
Lead to a base pair change in DNA
