devision

Question 1

what is the most common way bacteria devide

Answer 1

binary fission

Question 2

how do bacteria divide

Answer 2

binary fission

Question 3

what is binary fission

Answer 3

1 cell becomes 2 cells (2=sizes)

Question 4

what type of bacteria devide by budding

Answer 4

planctomycetes

Question 5

the cell cycle of a bacteria

Answer 5

-chromosome replication
-elonglation
-segregation
-z ring formation
-division

Question 6

you observe a ghost cell in your bacteria culture. what is the best explanation

Answer 6

the z-ring is formed prior to segregation during the cell devision cycle

Question 7

what is a ghost cell

Answer 7

cell with out chromosomes

Question 8

what is biofilm

Answer 8

-from free-living planktonic to attached community
-4 key steps
-not a target of antibiotics
-several regulators and environmental factors

Question 9

four key steps for biofilm formation

Answer 9

-attachement
-growth
-maturation
-detachment

Question 10

you work in the food industry and bio films are a major problem. you must keep surfaces free of bacterial contamination. what step of biofilm formation should you target

Answer 10

attachment

Question 11

quantifying growth of cells

Answer 11

each division adds two new cells
0 generation=1 cell
1 gen=2cells
2gen=4cells
3gen=8cells

Question 12

what division would result in doubling of the population

Answer 12

budding

Question 13

how to direct count using microscopy

Answer 13

-grid
-count cells in square
-challenges: dont know if bacteria is dead and could count dead ones
-if mobile they are hard to count

Question 14

how to direct count using current

Answer 14

-coulter counter
-measure electrical current
-downside is you cant distinguish dead form alive

Question 15

direct counting methods

Answer 15

coulter counter
microsopy

Question 16

viable counting methods

Answer 16

-dilution
-plating

Question 17

plating for counting bacteria

Answer 17

2 methods
-1)pour plate method
-bacteria sample mixed with warm agar
-sample poured onto sterile plate
-swirled around to mix, allowed to solidify
-plate incubated until colonies grow
-2) spread plate method
-sample (0.1mL) poured onto solid medium
-spread sample evenly over surface
-plate incubated until bacterial colonies grow in the surface of the medium

Question 18

most probable number

Answer 18

-inoculate 3 different volumes of water in test tube and see what comes back positive
-see if high number of coliforms
-due to fecal contamination
-which ferments lactose
-determines if water is safe

Question 19

turbidimetric

Answer 19

-measuring bacteria using optical density

Question 20

which method would be used to measure the concentration of bacterial contamination in processed BP

Answer 20

-total plate count
-gives you direct count and BP wont interfere

Question 21

how does bacteria grow

Answer 21

-predictably
-lag phase (no increase in number of living cells)
-log phase (exponential increase in number of living bacterial cells)
-stationary phase (plateau in number of living bacterial cells; rate of devision and death roughly equal
-death or decline phase (exponential decrease in number of living bacterial cells)

Question 22

during which phase of growth would antibiotics be most effective

Answer 22

log/exponential phase

Question 23

generation time

Answer 23

how long does it take one to become two, time for population to double

Question 24

if you start a bacterial culture with one bacterial cell, how many cells would be expected after 12 hours the generation time is one hour

Answer 24

2^12
4096

Question 25

how to tell that bacteria has the fastest growth time

Answer 25

the lowest number is always the fastest