(LE2) Genetic Exchange Flashcards
What is vertical gene transfer? Does it occur in prokaryotes, or eukaryotes?
occurs during reproduction between generations of cells
- occurs in all eukaryotes and prokaryotes (mutations only)
What is horizontal gene transfer? Does it occur in prokaryotes, or eukaryotes?
Transfer of genes between cells of the same generation
- occurs in prokaryotes only
What are methods of horizontal gene transfer?
Transformation
Transduction
Conjugation
What is transformation?
ability of some bacteria to take up “naked” DNA and incorporate it into its own genome. Must be a competent cell
What is recombination?
DNA sequence is homologous (alleles), they may recombine and the new DNA sequence replaces the old
- recipient has new properties
What was the significance of Griffith’s experiment with mice?
Proved recombination occurred within bacteria
- Living R strain, dead S strain injected. Dead S released naked DNA and was taken up by the R strain
What is the significance of using recombinant technology with E. coli?
Green fluorescent protein (GFP) added to E. Coli plasmid
- plasmid contains GFP and ampR
- only cells that can take up plasmid can grow on media containing ampicillin
- cells made competent by adding Ca2+
What is transduction?
transfer of DNA from one bacterial cell to another via a bacteriophage (bacterial viruses)
- results in recipient cell with new trait that is passed on
e.g., O157:H7 E. coli w/ shiga-like toxin
What is conjugation?
transfer of genetic material between bacterial cells via sex pilus
Describe F+ conjugation. What is the F plasmid?
F plasmid creates genes that build pilus
- F+ is able to make pilus and transfer plasmid to F- recipient cell
- Recipient cell now has F plasmid and becomes F+ cell
What is Hfr conjugation?
High frequency of recombination (F-factor in chromosome)
- F plasmid incorporates to bacterial chromosome
- DNA replicates and transfers across pilus. Not all F factor transfers. Recipient stays F-
What is R factor?
plasmids containing genes for antibiotic or toxin resistance
- often exchanged via conjugation