Microbiology Lab Exam Ii

Front 1

if heat is applied, microbes are _________.

Back 1

killed

Front 2

if cold temperatures are used, microbial growth is _____________.

Back 2

inhibited

Front 3

what are the 5 optimal growth ranges

Back 3

psychrophilic

psychrotrophic

mesophilic

thermophilic

hyperthermophilic

Front 4

0 - 20 centigrade

Back 4

psychrophilic

Front 5

20-30 centigrade

Back 5

psychrotrophic

Front 6

25-40 centigrade

Back 6

mesophilic

Hint 6

Front 7

45-65 centigrade

Back 7

thermophilic

Hint 7

Front 8

>80 centigrade

Back 8

hyperthermophilic

Front 9

Overall ______________ are more heat resistant than most other forms of life.

Back 9

bacteria

Hint 9

Front 10

factors affecting heat sensitivity of organisms

Back 10

container size

cell density

moisture content

pH

medium composition

Front 11

denatures enzymes, dehydrates microbes and kills by oxidation effects

Back 11

dry heat

Front 12

standard application temperature and time for dry heat is

Back 12

170 centigrade for 2 hours

Front 13

_______ ______ denatures enzymes more efficiently

Back 13

moist heat

Front 14

_______ ________ methods include pasteurization, boiling and autoclaving

Back 14

moist heat

Front 15

In __________________ temperatures are maintained at 72 centigrade for 15 seconds or 63 centigrade for 30 minutes to kill designated organisms that are pathogenic or cause spoilage.

Back 15

pasteurization

Hint 15

Front 16

__________ 100 centigrade for 10 minutes will kill vegetative bacterial cells; however, it doesn't inactivate endospores.

Back 16

boiling

Front 17

the most effective method of moist heat sterilization is _____________.

Back 17

autoclaving

Front 18

_______________ is the use of steam under pressure to sterilize things.

Back 18

autoclaving

Front 19

increased _____________ raises the boiling point of water and produces steam with a higher temperature.

Back 19

pressure

Hint 19

Front 20

standard conditions for ________________ are 15 psi at 121 C for 15 minutes.

Back 20

autoclaving

Front 21

_________________ is usually sufficient to kill endospores and render materials sterile

Back 21

autoclaving

Front 22

______________ _________ __________ is the length of time required to kill all bacteria in a liquid culture at a given temperature.

Back 22

thermal death time TDT

Front 23

____________ _________ __________ is the temperature required to kill all bacteria in a liquid culture in 10 minutes.

Back 23

thermal death point TDP

Front 24

____________ __________ ___________ is the time, in minutes, in which 90% of a population of bacteriua at a given temperature will be killed.

Back 24

decimal reduction time DRT or D value

Front 25

explain why fungi and Bacillus sometimes grow better after heat treatment.

Back 25

fungi and Bacillus can produce endospores which are heat activatedhou

Front 26

the decimal reduction time DRT is the time it takes to kill 90% of cells present. assume that a DRT value for autoclaving a culture is 1.5 minutes. how long would it take to kill all the cells if 10^6 cells were present? What would happen if you stopped the heating process at 9 minutes.

Back 26

there would be only 1 survivor

Front 27

a biological indicator used in autoclaving is a vial containing 10^9 _________________ _______________ cells that is placed in the autoclave with the material to be sterilized. After autoclaving the vial is incubated and examined for growth. why is this species used as opposed to E. coli or Bacillus subtilis?

Back 27

Geobacillus stearothermophilus

answer: it is hyperthermophilic which means it is only killed at temperatures in excess of 80 C

Front 28

give an example of:

incineration

pasteurization

autoclaving

Back 28

incineration- toasting

pasteurization- milk production

autoclaving- pressure cooking

Front 29

why are old and young bacillus used in the lab comparison of the bactericidal effects of dry heat and moist heat.

Back 29

bacillus species produce endospores which can withstand temperatures in excess of 100 C.

Front 30

____________ differs in wavelength and energy.

Back 30

radiation

Hint 30

Front 31

the __________ wavelengths have more energy.

Back 31

shorter

Front 32

x rays and gamma rays are forms of _____________ radiation. Their principal effect is to ionize water into highly reactive ______ _________ (with unpaired electrons) that can break strands of DNA.

Back 32

ionizing

free radicals

Hint 32

Front 33

variable effecting the influence of radiation?

Back 33

age of cells

media composition

temperature

Front 34

Some ______________ wavelengths are essential for biochemical processes.

Back 34

nonionizing

Hint 34

Front 35

animal cells synthesize ______ __ in the presence of light around 300nm

Back 35

Vitamin D

Hint 35

Front 36

is absorbed by

Back 36

green algae

green plants

photosynthetic bacteria

Front 37

Nonionizing radiation between 15 and 400 nm is called ______________.

Back 37

Ultraviolet

Hint 37

Front 38

Wavelengths below _____ nm are absorbed by air and do not reach living organisms.

Back 38

200 nm

Front 39

The most lethal wavelengths, sometimes called biocidal, are in the _____ range, 200-290 nm. these wave lengths correspond to the optimal absorption wavelengths of _____.

Back 39

UVC

DNA

Hint 39

Front 40

______ wavelengths (290-320 nm) can also cause damage to _____.

Back 40

UVB

DNA

Hint 40

Front 41

______ wavelengths (320-400 nm) are not as readily absorbed and are therefore less active on living organisms.

Back 41

UVA

Front 42

UV WAVELENGTHS
320-400 nm =

290-320 nm =

200-290 nm =

wavelengths < 200 nm =

Back 42

UVA

UVB

UVC

UV absorbed by air but not living things

Front 43

Wavelengths:

-biocidal=

-DNA absorbing=

-cause some damage to DNA=

Back 43

UVC

UVB

UVA

Front 44

Ultraviolet light induces __________ _________ in DNA, which result in mutation. mutations in critical genes may result in the death of the cell unless the damage is repaired.

Back 44

thymine dimers

Hint 44

Front 45

When thymine dimers are exposed to visible light, _____________ are activated; these enzymes split the dimers, restoring the ______ to its undamaged state.

Back 45

photolyases

Hint 45

Front 46

the process of thymine dimers being repaired by photolyases is called ________ __________ or photoreactivation.

Back 46

light repair

Hint 46

Front 47

Another repair mechanism, called ______ ________, is independent of light. Dimers are removed by endonuclease, _____ ___________ replaces the nucleotides, and _____ __________ seals the sugar-phosphate backbone.

Back 47

dark repair

DNA polymerase

DNA ligase

Hint 47

Front 48

As a sterilizing agent, ultraviolet radiation is limited by its poor _________________ ability.

Back 48

penetrating

Front 49

____________ _____________ is used to sterilize some heat-labile solutioons, to decontaminate hospital operating rooms and food processing areas and to disinfect ____________.

Back 49

ultraviolet radiation

wastewater.

Hint 49

Front 50

If the Bacillus had sporulated before exposure to radiation, would that affect the results of of the bacteria vs UV light experiment?

Back 50

endospores are only killed by autoclaving so the Bacillus would have regrown.

Front 51

Wide varieties of chemicals called ______________ agents are available for controlling the growth of microbes.

Back 51

antimicrobial

Front 52

_____________ are chemical agents used on inanimate objects to lower the level of microbes on their surfaces; ____________ are chemicals used on living tissue to decrease the number of microbes.

Back 52

Disinfectants

antiseptics

Front 53

Chemicals that result in bacterial death are called ____________ agents. those causing temporary inhibition of growth are ______________ agents.

Back 53

bactericidal

bacteriostatic

Front 54

additional variables to consider in selecting an antimicrobial agent include:

Back 54

pH, solubility, _________, organic material present, and ______.

Hint 54

toxicity

$ cost

Front 55

the important criteria when evaluating antimicrobial agents are:

Back 55

concentration

length of contact

cidal or static

Front 56

the standard method for measuring the effectiveness of a chemical agent is the _________ __________ ____________ _________'_ ____-_________ _____. Also known as the use dilution test.

Back 56

American official analytical chemist's use-dilution test.

Front 57

the three strains of bacteria us in the American official analytical chemist's use-dilution test. are:

Back 57

Salmonella enterica

Staphylococcus aureus

Pseudomonas aeruginosa

Front 58

in 1940 Selman A. Waksman isolated the antibiotic ______________, produced by an actinomycete. This antibiotic was effective against many bacteria that penicillin did not affect.

Back 58

streptomycin

Hint 58

Front 59

To minimize the variance between laboratories, the standardized ________-_______ _____ for agar diffusion methods is performed in many clinical laboratories with strict quality controls this test uses ________-_________ _____. the agar allows the antimicrobial agent of diffuse freely.

Back 59

Kirby-Bauer test

Mueller-Hinton agar

Hint 59

Front 60

the standardized Kirby-Bauer test for agar diffusion methods is performed in many clinical laboratories with strict quality controls this test uses ________-_________ _____. the agar allows the antimicrobial agent of diffuse freely.

Back 60

Mueller-Hinton agar

Hint 60

Front 61

Back 61

1.)the minimum inhibitory concentration MIC of an antibiotic is determined by testing for bacterial growth in dilutions of the antibiotic in nutrient broth.

2.) When the MIC is determine, inhibition zones can be correlated with MICs.

3.)Then, inhibition zones can be correlated to a standard table to use the disk diffusion method to determine susceptibility.

Front 62

the measure (millimeters) of the diameter of the area surrounding the Antimicrobial impregnated disk without bacteria.

Back 62

zone of inhibition

Hint 62

Front 63

the three terms referring to the diameter of the zone of inhibition are:

Back 63

Resistant

intermediate

susceptible

Front 64

Is the disk diffusion technique measuring bacteriostatic or bactericidal activity? Explain.

Back 64

bacteriostatic, until a subculture is inoculated to measure bactericidal action.

Front 65

In which growth phase is an organism most sensitive to an antimicrobial agent?

Back 65

Log phase

Front 66

Bacitracin

Cycloserine

Ethambutol

Isoniazid

Vancomycin

Beta-lactams

Monobactams

Back 66

Inhibit cell wall synthesis

Hint 66

Spectrum of action: narrow

Gram + bacteria

Va=MRSA

Cyloserine=TB

ethambutol=TB

Isoniazid=TB

Front 67

Aminoglycosides:

-Neomycin

-Streptomycin

-Tobramycin

Chloramphenicol

Lincosamides

-Clindamycin

Macrolides

-Azithromycin

-Erythromycin

Tetracyclines

Linezolid

Back 67

Inhibit protein synthesis

Hint 67

Spectrum of action: Broad

Gram +

Gram -

some fungi

some protozoa

Chloramphenicol= Typhoid FV

Front 68

Polymyxin

pyrazinamed (TB)

Back 68

alter cytoplasmic membranes

Hint 68

Spectrum of action: narrow

mostly gram+

Front 69

Dapsone

Sulfonamides

Trimethoprim

Back 69

Antimetabolites

Hint 69

Spectrum of action: broad

Gram +

Gram -

Front 70

Fluoroquinolones

-Ciprofloxacin

Metronidazole

Rifampin

Back 70

Inhibit nucleic acid synthesis

Hint 70

spectrum of action: broad
Gram+

Gram-

Front 71

What effect would the presence of tetracycline in the body have on penicillin therapy?

Back 71

tetracycline decreases effects of penicillin by pharmacodynamics antagonism. possible serious or life threatening reaction.