(LE2) Genetic Exchange

Question 1

What is vertical gene transfer? Does it occur in prokaryotes, or eukaryotes?

Answer 1

occurs during reproduction between generations of cells
- occurs in all eukaryotes and prokaryotes (mutations only)

Question 2

What is horizontal gene transfer? Does it occur in prokaryotes, or eukaryotes?

Answer 2

Transfer of genes between cells of the same generation
- occurs in prokaryotes only

Question 3

What are methods of horizontal gene transfer?

Answer 3

Transformation
Transduction
Conjugation

Question 4

What is transformation?

Answer 4

ability of some bacteria to take up “naked” DNA and incorporate it into its own genome. Must be a competent cell

Question 5

What is recombination?

Answer 5

DNA sequence is homologous (alleles), they may recombine and the new DNA sequence replaces the old
- recipient has new properties

Question 6

What was the significance of Griffith’s experiment with mice?

Answer 6

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

Question 7

What is the significance of using recombinant technology with E. coli?

Answer 7

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+

Question 8

What is transduction?

Answer 8

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

Question 9

What is conjugation?

Answer 9

transfer of genetic material between bacterial cells via sex pilus

Question 10

Describe F+ conjugation. What is the F plasmid?

Answer 10

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

Question 11

What is Hfr conjugation?

Answer 11

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-

Question 12

What is R factor?

Answer 12

plasmids containing genes for antibiotic or toxin resistance
- often exchanged via conjugation