Microbiology Lab Quiz 2

Front 1

Digital Pipettor

Back 1

- Used to accurately transfer liquids for quantitative results

- Work by air displacement

Front 2

Sterile, disposable plastic tip

Back 2

- Placed on the end of the pipettor to prevent cross contamination of samples and contamination of the instrument

Front 3

Metal shaft

Back 3

- Ejects the tip when pressed, so user doesn't touch tips

- Important when transferring microbial agents, or hazardous chemicals

Front 4

Cotton/Fiber Plugs

Back 4

- Sometimes with the tips to prevent possible contamination of the pipettor when transferring solutions containing these components

Front 5

0.1 -10 micrometers uL

10 - 100 micrometers uL

100 - 1000 micrometers uL

Back 5

3 Volume Ranges of the Digital Pipettors used in Lab

Front 6

1000
880
540

Back 6

Indicate the volume that would be dispensed on a 1000 uL unit

- 100

- 88

- 54

Front 7

Piston

Back 7

- When specific volume is set, the distance that this will move is determined, and therefore, the volume that will be transferred

Front 8

First Stop/Loading Stop

Back 8

- First point of resistance on plunger

Front 9

Second Stop/ Blow Out Stop

Back 9

- Needs to be reached to dispense all the liquid, since capillary action of the tip will actually retain some of the sample if only gone to the First Stop

Front 10

- Splattering

- Loss of reagents

- Incorrect volume to be dosed

Back 10

Pushing and releasing the button too quickly can cause what 3 possible sources of error?

Front 11

Third Stop/ Tip Eject Stop

Back 11

- Some pipettors also have this to pop the disposable tip off the end of the barrel

Front 12

20 Drops

1000 microliters uL

Back 12

1 mL contains how many drops? How many microliters?

Front 13

50 microliters uL

Back 13

1 Drop is about how many microliters?

Front 14

Psychrophiles

Back 14

- Grow below 10 C

Front 15

Mesophiles

Back 15

- Grow in a range of 20-40 C

- Found on body

Front 16

Thermophiles

Back 16

- Grow in a range of 50 - 75 C

- Found in hot springs

Front 17

Hyperthermophiles

Back 17

- Grow in a range above 80 C

Front 18

Optimum temperatures

Back 18

- Indicate the fragility or stability of their metabolic enzymes

Front 19

Pseudomonas fragi

Staphylococcus epidermidis

Bacillus stearothermophilus

Back 19

Give example of psychrophile, mesophile and thermophile.

Front 20

- Pseudomonas fragi

- Pseudomonas fragi; Staphylococcus Epidermidis

- Staphylococcus Epidermidis

- Bacillus stearothermophilus

Back 20

What bacteris would you expect to see at 4C? 25C? 37C? 55C?

Front 21

Bacillus stearothermophilus

Back 21

What bacteria had growth at 55 C?

Front 22

Pseudomonas fragi and Staphylococcus epidermidis

Back 22

What bacteria had growth at 25C?

Front 23

Pseudomonas fragi

Back 23

What bacteria had growth at 4C?

Front 24

Staphylococcus Epidermidis

Back 24

Which bacteria had growth at 37 C?

Front 25

Proteases

Lipases

Amylases

Back 25

3 Types of hydrolytic enzymes

Front 26

Amylase

Back 26

- Digest starch for they can absorb glucose for energy production

Front 27

Hydrolytic Enzymes

Back 27

- Some bacteria excrete this to digest nutrients around them so they can absorb the products for sources of energy, carbon and nitrogen

- Many digest starch for they can absorb glucose for energy production

Front 28

Bacillus subtilis

- Iodine binds to starch and gives black coloration, so if starch is consumed, halo appears

Back 28

Which bacteria is the one with the 'halo' around its growth? Does this indicate presence or absence of amylase enzyme? Explain.

Front 29

Catalase

Back 29

- Enzyme that converts toxic peroxide H2O2 to H2O and 1/2 O2

- Reaction shown by bubbles

Front 30

- Staphylococcus epidermidis has catalase - bubbles

- Enterococcus faecalis

Back 30

Identify the bacteria with bubbles. The one without. Which one is catalase present in?

Front 31

Enterococcus Faecalis

Back 31

- Gram positive, does not secrete catalase, present in gut (gastrointestinal tract)

Front 32

Cytochromes

Back 32

- Electron transport system of aerobic organisms contain many iron containing proteins called?

- High energy electrons from NADH and FADH2 are passed from these to the next and energy is extracted from them to make ATP

Front 33

Cytochrome C Oxidase

Back 33

- Last cytochrome in the chain

- Uses 2 protons (H+) to add to oxygen to make water (H2O)

- If this is present, it means all previous cytochromes are present

- Aids in the classification of bacteria's aerotolerance and identification of Gram negative organisms

Front 34

- Do not have cytochrome C oxidase

Back 34

Obligate Anaerobes and Enterobacteriaceae (enterics) which are Facultative anaerobes (have/do not have) cytochrome C Oxidase

Front 35

Oxidase Test

Back 35

- This test can be used to differentiate between Pseudomonads and Enterobacteriaceae

Front 36

Square with oxidase reagent will turn blue if chemical is oxidized, indicating presence of cytochrome C oxidase within 5-10 seconds

Back 36

What is positive result for oxidase?

Front 37

Pseudomonas aeruginosa; Cytochrome C Oxidase is present

Back 37

Identify the bacteria where color of square is blue. What cytochrome is present?

Front 38

Facultative Anaerobic

Back 38

- Grows in the presence or absence of O2, but prefers because aerobic cellular respiration is more energy efficient (> ATP)

Front 39

Strictly Anaerobic

Back 39

- O2 is toxic (Doesn't grow, or sometimes dies)

Front 40

Aerotolerance

Back 40

- Describes the ability/inability of organism to grow in presence of molecular oxygen

Front 41

Obligate Aerobe

Facultative Anaerobe

Obligate Anaerobe

Aerotolerant Anaerobe

Microaerophile

Back 41

5 Classifications of Aerotolerance

Front 42

Pseudomonas aeruginosa

Aerobic

Growth on top.

Back 42

Identify bacteria and its aerotolerance. Describe growth.

Front 43

Escherichia coli

Facultative Anaerobic

Growth through agar.

Back 43

Identify bacteria and its aerotolerance. Describe growth.

Front 44

Clostridium sporogenes

Strictly Anaerobe

Back 44

A test tube inoculated with a needle through agar deep has growth only on the bottom. This describes which bacteria and what kind of aerotolerance?

Front 45

Thioglycollate Media

Back 45

- Referred to as reducing media and is designed for cultivating anaerobes without an anaerobe jar

- Binds molecular oxygen and removes it

- Must be boiled and autoclaved to remove all dissolved gases from medium including O2

- Sometimes above 1 cm red layer is observed because of contact with air

Front 46

Resazurin (pink/red)

Back 46

- Dye that is included in medium to indicate presence of O2 by turning ____________, otherwise it is colorless.

Front 47

Pseudomonas aeruginosa

Aerobic

Growth on top.

Back 47

Identify bacteria and its aerotolerance. Describe growth.

Front 48

Escherichia coli

Facultative Anaerobic

Uneven growth through thioglycollate medium.

Back 48

Identify bacteria and its aerotolerance. Describe growth.

Front 49

Clostridium sporogenes

Strictly Anaerobe

No growth on top

Back 49

Identify bacteria and its aerotolerance. Describe growth.

Front 50

Anaerobe Jar

Back 50

- Provides an anaerobic environment by using a hydrogen generator to produce hydrogen gas to react with oxygen in the presence of a metal catalyst to produce water

Front 51

Methylene Blue

Resazurin

Back 51

2 Types of Oxygen Indicators - In its absence, colorless

Front 52

Direct Method

Back 52

- Basic mean to follow bacteria growth that produces actual numbers of cells

- Includes counting chambers and viable plate count

Front 53

Counting Chambers

Viable Plate Count

Back 53

2 Types of Direct Methods for following bacterial growth

Front 54

Indirect Method

Back 54

- Basic mean to follow bacterial growth that does not produce real numbers but relative amounts compared to the beginning of the experiment

- Include absorbance (spectrophotometer) and weighing dried samples of cells collected by centrifugation

Front 55

- Absorbance (spectrophotometer)

- Weighing dried samples of cells collected by centrifugation

Back 55

2 Types of Indirect Methods of following bacterial growth

Front 56

Viable Plate Count

Back 56

- Take sample from culture, dilute it, then plate samples to grow

- Colonies can be counted, then multiplied by the inverse of the dilution to attain original number of colony forming units in broth culture

- Only living cells are counted

Front 57

Counting Chamber

Absorbance

Back 57

2 Methods that count both living and dead cells

Front 58

Important to tell if one is sick or something is contaminated

Back 58

Counting Bacteria is important because?

Front 59

TNTC Too Numerous to Count

Back 59

- 10^9 Cells/mL

- Lawn (Confluent Growth) observable on plate

- Error of margin becomes too drastic

Front 60

Serial Dilution

Back 60

- Solves problem of TNTC

- Dilutes original sample into series of sterile water or broth tubes

- Assumed there will be plated dilution "just right" Goldilocks Principle (30-300)

Front 61

Amount Transferred Divided by Total Volume

Back 61

Equation for Dilution Factor

Front 62

Colony Count on Plate divided by Dilution Factor

Back 62

How to calculate Colony Forming Units by mL?

Front 63

Short Wavelength (260-280 nm) UV Radiation

Back 63

- Mutagenic because it excited nucleic acid bases in DNA and causes formation of thymine dimers

- Considered bactericidal since mutations can be lethal to bacteria

What is the range?

Front 64

Thymine Dimer

Back 64

- AKA pyrimidine dimer

- Forms double bonds with each other, because its nucleotide is most susceptible to UV radiation

Front 65

Cystic Fibrosis

Multiple Sclerosis

Back 65

- DNA polymerase can bind up to 1 million bases per second but gets stuck at T = T; asks it self, should I halt? Or let cell die.

- Thus it keeps going with mutation, eventually binding G to T, then later base C

- These thymine dimers can cause what 2 diseases?

Front 66

Serratia marcescens

Back 66

- Environmental organisms that produced red pigment called prodigiosin when grown at 25C or does not produce the pigment and appears white at 37 C

Front 67

Blood Poisoning

Back 67

- Fatal, kills within 8 hours

Front 68

Mouth

Back 68

Streptococci

Staphylococcus

Influenzae

Examples of bacteria in the?

Front 69

Opportunistic Pathogens

Back 69

- Microorganisms are evolving new mechanisms of pathogenicity and resistance to chemotherapeutic agents
Ex: E. coli, Staphylococcus aureus, Mycobacterium tuberculosis, Neisseria gonorrhoeae

Front 70

Escherichia Coli

Back 70

Important part of our natural intestinal flora, that picked up plasmids from other bacteria to produce Shiga-like toxin and become more invasive as seen in the deadly O157:H7 strain

Front 71

Neisseria gonorrhoeae

Back 71

- Now become resistant to all drugs except one class of cephalosporins

Front 72

Normal Flora

Back 72

- On skin that is in competition with transient microbes, and easily transfer them to one another

Front 73

Hand Washing

Back 73

- Most effective practice to limit transmission of pathogens from one person to another

- Best and easiest method to cut nosocomial infections (hospitals and clinics) which kill thousands of patients every year

- Removes all transient microbes and part of your normal flora

Front 74

More

More

Back 74

The higher the treatment (soap+ scrub+ water) the (less/more) the number of colonies and there are (less/more) number of different colony forms.

Front 75

Antibiotics

Back 75

- Not effective against Gram +

- More effective against Gram -

Front 76

Susceptibility

Back 76

- Means effective disinfectant

Front 77

- Concentration and rate of diffusion of the chemotherapeutic agent on each disk

- Density and age of bacterial growth

- Thickness and viscosity of medium

- Temperature and time of incubation

Back 77

Variables of Kirby-Bauer assay

Front 78

Mueller-Hinton Agar

Back 78

Appropriately enriched medium to support most microorganisms studied

- Prepared to standardized recipe to guarantee global ingredient and viscosity consistency and a precise volume (20 mL) so medium thickness is consistent

Front 79

McFarland No. 0.5 Turbidity standard

Back 79

2-3 Drops insures standard turbidity, must be from suspension of inoculum prepared from 24 hour broth culture

Front 80

1.5 * 10^8 bacteria/mL

Back 80

McFarland No. 0.5 Turbidity standard yields bacterial counts of about?

Front 81

-Inanimate objects or living tissue

Back 81

Difference between disinfectant and antiseptics?

Front 82

Disinfectants

Back 82

- Less stable than antibiotics or are volatile and therefore standardization is more difficult

- So evaluation is a little more difficult

Front 83

- Clorox Bleach

- Peroxide, betadine

- Ethanol

Back 83

Example of Disinfectants

2 Examples of Antiseptics

Example that can be both