Section 8: Genetic Recombination

Question 1

Transformation (vs. conjugation and transduction)

Answer 1

• Griffith
• DNA transforms bacterial cells
• DNA is not contained, as cells die, DNA is released
• recipient cells must be able to take up DNA (COMPETENT; during log phase)
• competence can be induced by introduction of CaCl2 or electroporation (electrical current)

Question 2

Conjugation (vs. transformation and transduction)

Answer 2

requires contact bw two cells and can be transferred via (plasmid DNA or chromosomal DNA)

Question 3

Plasmid DNA transfer (Conjugation)

Answer 3

Plasmid transferred (F plasmid; fertility plasmid); 
donor = F+ (male)
recipient = F- (female)
plasmids carry information that code for formation of sex pili

Question 4

Chromosomal DNA transfer (Conjugation)

Answer 4

F plasmid can transfer chromosomal DNA IF first integrates into chromosome and then excises, bringing a portion of the chromosome (excised cell by Hfr is aka F’ cell)
- cell with F plasmid integrated into chromosome = Hfr cell

Question 5

Transduction (vs. conjugation and translation)

Answer 5

transfer of DNA from cell to cell via bacteriophage. they interact in two ways: lytic and lysogenic.
there are two types of transduction: generalized and specialized.
LYTIC IS ALWAYS GENERALIZED;
LYSOGENIC IS ALWAYS SPECIALIZED*****

Question 6

Lytic interaction (transduction)

Answer 6

• phage (virus) overtakes the cell
• new phage occurs, only bacterial chromosomal DNA is incorporated
• cell lyses and expels new bacterial DNA - phage is capable of transduction

Question 7

Lysogenic interaction (transduction)

Answer 7

• phage (virus) DNA integrates into host DNA (temperate phase) and remains there for few to many generations
• EVENTUALLY BECOMES LYTIC
• if permanent in bacterial DNA, called lysogenic conversion and thus is a new bacterial strain

Question 8

Generalized transduction

Answer 8

ALWAYS PAIRED WITH LYTIC
during production, some phages accidentally package only bacterial chromosomal DNA, not viral DNA in capsid. Can still infect cells, but only with bacterial chromosomal DNA

Question 9

Specialized transduction

Answer 9

ALWAYS PAIRED WITH LYSOGENIC
contains both viral DNA and bacterial chromosomal DNA; packages specific chromosomal DNA near where viral DNA is integrated during lysogenic phase