Exam 2 - Chapter 8 Flashcards
Mutation
Changes the existing nucleotide sequence of a cell’s DNA
Vertical Gene Transfer
The passing down of mutations to the progeny (daughter cells)
Progeny
Daughter cells
Horizontal Gene Transfer
The movement of DNA from one organism to another
Auxotroph
A mutant that requires a growth factor (auxo means increase)
Prototroph
A mutant that does not require a growth factor (proto means earliest form of)
Wild Type
The typical phenotype of strains isolated from nature
Reversion
When a mutation changes back to its original, non-mutated form
Base Substitution
When an incorrect nucleotide sequence is incorporated. Three kinds: Silent, Missense, and Nonsense
Point Mutation
When only one base pair is changed
Silent Mutation
A base change occurs, but the new codon still codes for the same amino acid as the wild type
Missense Mutation
The new codon codes for a different amino acid. Most cases the protein only functions partially
Nonsense Mutation
The new codon is a stop codon, making a shorter and usually non functioning protein
Knockout Mutation
Totally inactivates the gene
Frameshift Mutation
When one or two nucleotides are ADDED. Usually results in a knockout mutation
Transposons (Jumping Genes)
Mutagens that are pieces of DNA that can move from one location to another in a cell’s genome, by transposition, inactivating the genes
Induced Mutation
Genetic changes that occur due to an influence outside the cell, such as radiation
Direct Selection
The mutant will grow but the parent won’t
Indirect Selection
Is used to isolate an auxotrophic mutant from a prototrophic parent. Both the parent and mutant can grow in certain mediums
Replica Plating
This is for isolating auxotrophic mutants in indirect selection. You get one medium for both the mutant and parent to grow in. Then you get a nutrient plate and a bs plate and transfer the medium to both of these “replica plates” the parent will grow in both but the mutant will only grow in the nutrient plate
Recombinants
A recipient of horizontal gene transfer. These genes have new characteristics and copies of the original strains
DNA-mediated Transformation
“Naked” DNA is taken up from the environment by a bacterial cell
Transduction
DNA is transferred from one bacterial cell to another by a bacteriophage (a virus that infects bacteria)
Conjugation
DNA is transferred during cell to cell contact. Plasmid transfer is one kind, chromosome transfer is another but only Hfr cells can be donors
Conjugative Plasmids
Direct their own transfer from donor to recipient cells
Core Genome
The genes that are in the entire gene pool of a species
Mobilome (Mobile Gene Pool)
The genes that can be transferred
Plasmids
Circular double-stranded DNA replicon; generally code only for non-essential genetic information
R Plasmids (Resistance Plasmids)
Develop resistance to medications. Consist of Resistant gene and Resistance Transfer Factor (RTF), used for transferring the R genes via conjugation
Base Analogs
Structurally resemble nucleobases but have different hydrogen-bonding properties
Intercalating Agents
Insert between adjacent base pairs during replication, either adding or deleting a base pair, resulting in a frameshift mutation
Mismatch Repair
Used to repair errors by breaking off the section with the error, which is then redone by DNA ligase and polymerase
Photoreactivation (Light Repair)
Enzyme uses energy from visible light to break apart the thymine dimers caused by UV radiation
Excision Repair (Dark Repair)
Similar to mismatch repair, the bacteria recognizes where the thymine dimer is, and breaks this segment off. DNA ligase and polymerase then seal it
SOS Repair
Last resort to fix thymine dimer
