bacterial gene transfer 6.2

Question 1

plasmids may have genes that confer what novel phenotypes on cells

Answer 1

• resistance to antibiotics
• production of toxins
• the capacity to metabolize unusual substrates such as pesticides or industrial solvents

Question 2

Some antibiotic resistance is conferred by?

Answer 2

R plasmids

Question 3

R plasmids may confer resistance to as mane as?

Answer 3

five different antibiotics at once

Question 4

R plasmids, through conjugation, can rapidly?

Answer 4

disseminated through bacterial population

Question 5

PILUS

Answer 5

involved in conjugation to other bacteria of same species; viruses that infect bacteria sometime use these as
receptors

Question 6

what are the 6 characteristics of Pilus?

Answer 6

 requires cell-to-cell contact.
 Is referred to as bacterial mating
 plasmid or plasmid-chromosome can transfer
 Donor, but not the recipient, possesses a sex-pilus
 occurs during DNA replication
 Only one strand of DNA transfers from donor to recipient

Question 7

what are the 6 characteristics of Pilus?

Answer 7

 requires cell-to-cell contact.
 Is referred to as bacterial mating
 plasmid or plasmid-chromosome can transfer
 Donor, but not the recipient, possesses a sex-pilus
 occurs during DNA replication
 Only one strand of DNA transfers from donor to recipient

Question 8

Conjugative plasmids initiate gene transfer by altering the cell surface to allow?

Answer 8

contact between the F-plasmidcontaining donor cell (F+ cell) and F-plasmidless recipient (F- cell)

Question 9

plasmid gene codes for the production of a?

Answer 9

sex pilus tha tinitiates pair formation

Question 10

What is DNA transferred by in conjugation?

Answer 10

conjugation bridge (once it is formed)

Question 11

transfer of plasmid DNA is accompanied by its?

Answer 11

replication

Question 12

5 general steps of conjugation?

Answer 12

1) pilus retracts
2) cell pairs are stabilized; F plasmid nicked in one stranf
3) transfer of one strand from F+ cell to F- cell; F plasmid stimutaneously replicated in F- cell
4) synthesis of the complementary strand beginsin the recipient cell
5) completion of DNA transfer and ssynthesis; cells separate

Question 13

The Formation of Hfr Strains and
Chromosome Mobilization (for conjugatoni; 4 steps)

Answer 13

1) The donor cell chromosome can be mobilized for transfer to a recipient cell.
2) This requires F plasmid integration into the host chromosome to produce an Hfr phenotype.
3) Transfer of the host chromosome along with the integrated F plasmid occurs with varying degrees of completion
4) The variety in host chromosomeplasmid transfer allowed for the first mapping of the bacterial chromosome

Question 14

F plasmid

1) integraes into chromosome where?
2) is considered what type of plasmid?
3) always mobilizes host chomosomes where?
4) allows for high frequency of?
5) prevents donor from being?
6) impreciseexcision from host chromosome results in?

Answer 14

1) at sever SPECIFIC sites
2) conjugative plasmid
3) mobilizes host chromosomes starting at the SAME spot
4) high frequency of chromosomal transfer (Hfr) or recombination
5) prevents donor from being recipient
6) results in an F’ plasmid with a piece
of host DNA or without any host chromosomal DNA (F plasmid)

Question 15

What is IS?

Answer 15

IS =insertion sequence

*regions of DNA sequence homology between chromosomal and F plasmid DNA

Question 16

conjugation takes how long?

Answer 16

as much as 100 minutes

*goes to closest host gene first

Question 17

plasmids are used for?

Answer 17

gene cloning

Question 18

Cloning of foreign DNA into plasmid

vectors with what 2 genes?

Answer 18

a lacZ β-galactosidase gene and an antibiotic resistance gene