topic 5

Question 1

why do we use solid agar medium?

Answer 1

because bacteria cannot travel far on the surface of the gell thus cells remain together and form clumps so that they are visible to the naked eye

Question 2

what is a colony

Answer 2

a mass that reaches 10^7 cells and it becomes visible to the naked eye which is derived from a single original cells

Question 3

what are cell clones

Answer 3

members of the colony that have a single genetic ancestor

Question 4

what are prototrophic bacteria

Answer 4

wild-type bacteria that can grow and divide in minimal media

Question 5

what is in minimal media

Answer 5

inorganic salts, carbon source for energy, and water

Question 6

what are auxotrophic mutants?

Answer 6

mutant cells that will not grow unless the medium contains a specific cellular building block

Question 7

what are resistant mutants

Answer 7

mutants that can divide and form colonies in the presence of an inhibitor

Question 8

what does lac- indicate

Answer 8

cannot utilize lactose as a carbon source

Question 9

what does gal- indicate

Answer 9

cannot utilize galactose as a carbon source

Question 10

what does bio- indicate

Answer 10

Requires biotin added as a supplement to minimal
medium

Question 11

what does arg- indicate

Answer 11

Requires arginine added as a supplement to
minimal medium

Question 12

what does met- indicate

Answer 12

Requires methionine added as a supplement to
minimal medium

Question 13

what does str^r indicate

Answer 13

Resistant to the antibiotic streptomycin

Question 14

what does str^s indicate

Answer 14

Sensitive to the antibiotic streptomycin

Question 15

what is conjugation

Answer 15

the physical union of bacterial cells which causes DNA transferring

Question 16

what is the fertility factor

Answer 16

the fertility factor is a circular DNA molecule called the plasmid that allows for a bacterial cell to be a donor

Question 17

where does the plasmid replicate

Answer 17

in the cytoplasm

Question 18

how does F plasmid transfer genetic information to the recipient cell?

Answer 18

the F plasmid in the donor cell makes a single-stranded vers of itself through rolling circle replication which produces a single-stranded DNA that goes into the recipient cell

Question 19

how are F plasmids from +F donor cells are transmitted rapidly to F- recipient cells

Answer 19

rolling circle replication

Question 20

is the bacterial chromosome transferred in rolling circle replication?

Answer 20

no

Question 21

what is the purpose of a pilus

Answer 21

it pulls two bacteria together

Question 22

what creates an Hfr strain

Answer 22

when the F plasmid gets integrated to the host chromosome

Question 23

why dont most F- when crossed with Hfr don’t convert into Hfr or F-

Answer 23

because the part of F that confers donor ability was transmitted as the last element in the linear chromosome

Question 24

what is the shape of the Hfr chromosome

Answer 24

circular double stranded

Question 25

what are the start and end of the Hfr chromosome

Answer 25

origin and terminus

Question 26

what are the two states in which a fertility factor can exist

Answer 26

plasmid state - free cytoplasmic element which is easily transferred to F- recipients

integrated state- part of a circular chromosome where F is transmitted very late in conjugation

Question 27

what is an endogenote

Answer 27

the complete genome for the recipient cell before the new material is added

Question 28

what is ann exogenote

Answer 28

the incomplete genome from the Hfr donor cell

Question 29

what is a merozygote

Answer 29

partial diploid where there is an endogenote and exogenote

Question 30

what is transformation in bacteria

Answer 30

picking up free DNA from the enviroment or dead bacterial cells

Question 31

what is an exconjugant

Answer 31

cell that contains fragment if donor DNA; cell that has participated in conjugation

Question 32

what has the complete genome (exogenote and endogenote)

Answer 32

endogenote

Question 33

what trait do you select for when trying to get recobination frequency in bacteria

Answer 33

the last one to make sure all other markers exist in culture

Question 34

what is the cycle of host cell lysis by phage

Answer 34

bacteriophages infect DNA by inserting their DNA -> phage proteins are synthesized and genetic material is replicated and the host chromosome is degraded -> the phages are then assembled within host cell -> then lysis occurs where the phages are freed from host membrane

Question 35

what is a plaque

Answer 35

a clear area which all bacteria have been lyses by phages

Question 36

what is the shape of phage DNA

Answer 36

circular or linear

Question 37

what is transduction

Answer 37

transfer of genetic material from a bacterial donor to a bacterial recipient by a phage

Question 38

process of generalized transduction

Answer 38

donor bacterium is infected by phage -> donor DNA is chopped up -> assembly of phages where some take up bacteria genome -> all phages are extracted -> phages infect new bacteria -> then u select for traits to see if bacteria gene was transducted

Question 39

how does generalized transduction help us map the bacteria chromosome

Answer 39

the closer the bacteria genes are in the chromosome, the more likely they are to get packed together into a phage (cotransducted)

Question 40

the larger the cotranduction frequency, the _______ the genes

Answer 40

closer

Question 41

the larger the recombination frequency, the _____ the genes

Answer 41

farther