Quiz 4

Front 1

One method commonly used to determine the number of bacteria in milk, foods, and water is called:

Back 1

Standard plate count

Front 2

How many colony forming units (CFU) are on a countable plate?

Back 2

30-300 CFU

Front 3

How do we find the number of CFU/g of sample?

Back 3

We take the number of CFU (30-300) and multiply it by the dilution factor (the recipricol of the dilution) and this equals= CFU/g sample

Front 4

Will all bacteria grow on general purpose media?

Back 4

Only aerobic and facultative bacteria will grow and any anaerobes will not be counted

Front 5

Sterile tubes or bottles containing measured amounts of sterile water are called:

Back 5

Blanks

Front 6

Highest dilution showing a positive reaction is called:

Back 6

Titer

Front 7

Any positive reaction

Back 7

Serotype

Front 8

What might the number of bacteria in soil tell you about the soil? How about the number of bacteria in the food sample?

Back 8

The number of bacteria is probably higher in the soil than in the food samples. Although Spoiled yogurt is an exception. Because of the higher amount of bacteria in the soil, there is a greater amount of growth as a result when plated on nutrient agar.

Front 9

What is the difference between "sterile" and "disinfectant?"

Back 9

Sterilization is the destruction of all forms of life. There is no life present when its sterile.

Disinfection is the destruction of vegetative pathogens which can still contain living microbes.

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Front 10

Substances or conditions that inhibit the growth of bacteria without killing them is called:

Back 10

Bacteriostatic

Front 11

Substances or conditions that kill bacteria is called:

Back 11

Bactericidal

Front 12

Lethal to Fungi

Back 12

Fungicide

Front 13

This kills and inactivates Viruses

Back 13

Virucide

Front 14

Agent that kills spores

Back 14

Sporicidal agent

Front 15

This has activity against a wide range of mimcroorganisms

Back 15

Germicide

Front 16

Controlling microbial growth involves what two things?

Back 16

Keeping them alive and enhancing their growth

Front 17

Cells replicating their chromosomes (DNA) and then forming a septum that divides the cell into two daughter cells each containing a complete chromosome

Back 17

Binary Fission

Front 18

The amount of time it takes for a cell to replicate itself is termed:

Back 18

Generation Time/ Doubling Time

Front 19

The pattern that bacteria follow when introduced to a new environment:

Back 19

Growth Curve

Front 20

Factors that affect death due to heat:

Back 20

1. number of bacteria present 2. Growth phase/log phase:young bacteria are less resistant 3. Most resistant to pH 7 4. Osmotic pressure- Where h2o moves across a membrane due to concentration gradient

Front 21

What is only produced when needed?

Back 21

inducible enzymes

Front 22

how do moist heat methods kill bacteria?

Back 22

Kills by denaturing proteins

Front 23

What are the moist heat methods?

Back 23

1. Boiling in water

2. Tyndallization (AKA Intermittent or Fractional Sterilization)

3. Autoclaving

4. Pasteurization

Front 24

Based on our poll data in Lab, did pasteurization result in bactericidal?

Back 24

No. All bacteria lived through pasteurization

Front 25

Cold Temperature methods:

Back 25

1. Low temp

2. Freezing

3. Filtration

Front 26

Slows enzyme activity, bacteriostatic, effects are reversible

Back 26

Low temperature

Front 27

Usually prevents growth and toxin production, but generally does not cause death of organism

Back 27

Freezing

Front 28

Used for heat labile liquids- sterilizes without use of heat

Back 28

Filtration

Front 29

Dry Heat Methods

Back 29

1. Direct flaming

2. Incineration- burning to ashes

3. Hot air sterilization- drying oven (metal instruments)

Front 30

Force where h2o moves across a membrane due to concentration gradient

Back 30

Osmotic Pressure

Front 31

The two types of radiation used in disruption of bacteria:

Back 31

2. Ionization radiation

2. Nonionizing radiation

Front 32

Used to sterilize plastic syringes, surgical gloves, food, etc.

Back 32

Ionization radiation

Front 33

Forms thymine dymers "kink" in DNA and inhibits replication + protein synthesis.

Back 33

Non-ionizing radiation

Front 34

Growth curve consists of 4 phases:

Back 34

1. Lag phase

2. Logarithmic or exponential growth phase

3. Stationary phase

4. Decline or death phase

Front 35

At this stage there is little or no replication. Bacteria are adjusting to their new environment and synthesizing enzymes to utilize nutrients in the environment.

Back 35

Lag Phase

Front 36

As nutrient becomes less available and the accumulation of waste products becomes more toxic the death rate exceeds the rate of replication

Back 36

Decline or death phase

Front 37

The death rate equals the rate of cell replication due to the accumulation of waste products

Back 37

Stationary Phase

Front 38

At this phase, bacteria have adapted to the new environment and are metabolically active and reproduce exponentially

Back 38

Log phase (exponential growth phase)

Front 39

In which phase are bacteria more easily inhibited or killed?

And why?

Back 39

Log phase. Because metabolism is maximal during this phase and most antimicrobial substances are able to disrupt metabolisms.

Also, the cells are dividing so rapidly in this phase they don't form thick cell walls and don't have thick cell walls or endospores.

Front 40

In which stage are these harder to destroy?

Back 40

Stationary phase. Because they have a lower metabolic rate, thick cell walls, and well developed capsules and endospores.

Front 41

The movement of water across a semipermeable membrane

Back 41

Osmosis

Front 42

Water will move from an area of ________ solute to an area of __________ solute concentration.

Back 42

Low to high

Front 43

The force with which water moves across a membrane due to a concentration gradient

Back 43

Osmotic Pressure

Front 44

If surrounding environment contains a high solute concentration relative to interior of cell:

Back 44

Hypertonic

Front 45

The loss of water from the cell will cause the cytoplasm to shrink away from the cell wall

Back 45

Plasmolysis

Front 46

Bacteria that love salt and can continue to grow in high salt concentrations are called:

Back 46

halophiles

Front 47

A net movement of water into the cell due to low solute concentration

Back 47

Hypotonic

Front 48

If the concentration is the same inside and outside it is called:

Back 48

Isotonic

Front 49

A double layered agar plate with a concentration gradient in upper layer

Back 49

Gradient Plates

Front 50

Which organisms grew best in a high NaCl concentration?

Back 50

Staphylococcus Aureus

Front 51

Which organisms grew best in a high sucrose concentration?

Back 51

Saccharomyces

Front 52

How does a high solute concentration inhibit the growth of bacteria?

Back 52

Because it causes a hypertonic environment, a net movement of water leaves the cell causing metabolism to decrease which inhibits growth of bacteria.

Front 53

________________________ of an organism's environment has a profound influence on its growth:

Back 53

Hydrogen Ion Concentration

Front 54

The pH at which the organism will grow best is termed:

Back 54

Optimum pH

Front 55

pH below the ______________ or above ________________ will prevent their growth.

Back 55

minimum pH or maximum pH

Front 56

Neutrophiles

Back 56

Bacteria that grow optimally at a neutral pH

Front 57

Acidophiles

Back 57

Bacteria that grow optimally in an acidic environment

Front 58

Alkalinophiles

Back 58

Inhibit alkaline soils and water and can continue to grow at a pH of 11.5 and a few species can grow at a pH as high as 12

Front 59

According to our polled data from pH experiment, E. Coli grew best in NB without glucose at what pH?

Back 59

pH 7

Front 60

According to our polled data from pH experiment, E. Coli grew best in (NB) Nutrient broth with 1% glucose at what pH?

Back 60

pH. 7

Front 61

According to our polled data from the pH experiment, Saccharomyces grew best in Nutrient Broth without glucose at what pH?

Back 61

pH 6

Front 62

According to our polled data from the pH experiment, Saccharomyces grew best in Nutrient Broth with 1% glucose at what pH?

Back 62

pH 9

Front 63

As temperature increases, what happens to Enzyme activity?

Back 63

Enzyme activity increases as temperature increases. Eventually, heat will denature the 3-dimensional structure of the enzyme rendering it inactive.

Front 64

As temperature is lowered, what happens to enzyme activity?

Back 64

Enzyme activity slows down and the metabolic activity and growth of organism slows down too. (think how refrigeration controls growth and prevents spoilage of food)

Front 65

Temperature range for different bacteria species is:

Back 65

20-30 Celsius

Front 66

Bacteria that can grow within a temperature range of 0 degrees to 20 degrees Celsius are termed:

Back 66

Psychrophilic

Front 67

Bacteria that grow optimally in a range of 20 degrees to 45 degrees Celsius are termed:

Back 67

Mesophiles (middle loving). Most human pathogens are mesophillic (37 degrees Celsius).

Front 68

Organisms that grow in mesophilic range and slowly at refrigerator temperature are termed:

Back 68

psychrotolerant

Front 69

Some bacteria produce toxins capable of causing food spoiling. These bacteria are termed:

Back 69

Psychrotolerant

Front 70

Bacteria that grow in a temperature range of 40-70 Celsius

Back 70

thermophiles (heat loving)

Front 71

Bacteria that have an optimal growth temperature of 80 degrees Celsius and are capable of growing in hot springs and geysers are termed:

These are valuable in biotechnology

Back 71

Hyperthermophiles or extreme thermophiles

Front 72

What was the optimal growth temperature for Bacillus Stearothermophilus?

Back 72

55 degrees Celsius (Thermophilic)

Front 73

What was the optimal growth temperature for Escherichia Coli?

Back 73

35-37 degrees Celsius (Mesophilic)

Front 74

What was the optimal temperature for Pseudomonas Flourescens?

Back 74

Room Temperature 23 degrees Celsius (mesophilic)

Front 75

What was the optimal temperature for Staphylococcus Aureus?

Back 75

Fridge temperature 1.2 degrees celsius (Psychrophilic)

Front 76

Which organisms grew well in the refrigerator?

Back 76

Pseudomonas Flouresces

Front 77

What are the two basic types of heat used to control microbial growth?

Back 77

1. Dry heat

2. Moist heat

Front 78

Dry heat methods kill by what means?

Back 78

By denaturing proteins and oxidation (burning) of vital structure and metabolic chemicals

Front 79

Flaming of loop during lab or flaming the lip of a test tube:

Back 79

Direct flaming

Front 80

Commonly used to sterilize glassware and metal instruments, oils, and powders. Using circulate of Hot air

Back 80

Drying ovens

Front 81

Used to dispose of contaminated materials in health care facilities and to stop the spread of disease in cattle or poultry

Back 81

Incineration

Front 82

Moist heat methods kill by what methods?

Back 82

Primarily by denaturing proteins, but can also damage cell membranes and nucleic acids

Front 83

Moist heat vs. Dry heat:

Back 83

Moist heat is more penetrating than dry heat and can be effective at a lower temperature in less time.

Front 84

This type of moist heat kills most vegetative cells but does not kill endospores. Does not result in sterilization but disinfection for general purposes:

Back 84

Boiling in water

Front 85

Sterilizing requiring the material to be heated on three successive days and incubating the material in between heat treatments

Back 85

Tyndallization

Front 86

Using steam heat under pressure and is one of the most reliable means of sterilization:

Back 86

Autoclaving

Front 87

Used in processing milk products. Does not result in sterilization but kills vegetative pathogens and some microorganisms involved in food spoilage:

Back 87

Pasteurization

Front 88

Basic principle with heat treatment: by ___________ the temperature you can ___________ the amount of time needed.

Back 88

increasing temperature: decrease the amount of needed time

Front 89

_________ the temperature you _________ the time and achieve the same degree of disinfection:

Back 89

lowering the temperature, you can increase the time needed.

Front 90

Three types of pasteurization is used based on the principle that increasing the temperature decreases the disinfecting time and lowering the temperature you increase the amount of time needed for disinfection.

Back 90

1. Low-temperature holding method

2. High-temperature short-time (flash time)

3. Ultra high temperature

Front 91

This type of pasteurization method uses 72 degrees Celsius for 15 seconds:

Back 91

High temperature short time (flash)

Front 92

This type of pasteurization method uses 63 degrees Celsius for 30 minutes:

Back 92

Low- Temperature holding method

Front 93

This type of pasteurization method uses a temperature raised from 74 degrees to 140 degrees Celsius in less than 5 seconds. lowers the temperature back to 74 degrees Celsius. (ex: boxed milk)

Back 93

Ultra-high temperature method

Front 94

According to our polled data, which method of pasteurization worked to kill bacteria?

Back 94

121 degrees Celsius for 15 minutes

Front 95

X-rays and gamma rays which are short wavelength, high energy, and very penetrating are forms of which type of radiation?

Back 95

Ionizing radiation

Front 96

Describe Nonionizing radiation:

Back 96

UV light is of longer wavelength than ionizing radiation. Wavelengths below 200nm are absorbed by the air and are ineffective in controlling microbial growth except in a vacuum. UV light is most lethal at a wavelength of 260nm which corresponds to wavelength that is absorbed optimally by DNA

Front 97

What do thymine dimers do?

Back 97

disrupt DNA replication and transcription

Front 98

How is UV light limited?

Back 98

1. prolonged exposure can damage human tissues causing burns, premature aging of skin, cancer, and damage to cornea of eyes

2. It does not penetrate most materials

Front 99

How is UV light most effective?

Back 99

1. to reduce the number of microbes on surfaces

2. reduces the concentration of airborne microbes in operating rooms, isolation wards, and areas of food preparation.

3. significantly reduce microbes in sewage water without introducing harmful chemicals into environment

Front 100

Bacterial cells can possess enzymes that allow them to repair the damage done to DNA by exposure to UV light. What are these two types called?

Back 100

1. Dark repair

2. Light repair

Front 101

involves an endonuclease that can function without visible light and is able to remove pyrimidine dimers

Back 101

Dark repair

Front 102

Involves pyrimidine dimerase called photoreactivating enzyme which is activated by visible light in the blue and green spectrum

Back 102

Light repair

Front 103

In the experiment UV light, we placed the plates at what temperature for 48 hours before reading them?

Back 103

Room temperature

Front 104

Substances used on inanimate objects to kill or inhibit growth of microorganisms

Back 104

Disinfectant

Front 105

Antimicrobial substances used on living tissue:

Back 105

Antiseptic

Front 106

Soaps and detergents decrease surface tension between molecules and emulsify fats and oils

Back 106

Surfactants

Front 107

Why are soaps and detergents poor antimicrobial agents?

Back 107

They require a mechanical removal by scrubbing and rinsing. This is why rinsing is so important in hand washing.

Front 108

Quaternary Ammonium Compounds

Back 108

Used as both disinfectants and antiseptics. Common ingredient in mouthwash, contact lens solution, and lab bench disinfectants.

Front 109

What are the disadvantages of using Quats?

Back 109

1. They tend to be neutralized by soaps and anionic detergents

2. inactivated by organic matter (readily absorbed by cotton/gauze)

3. Support the growth of Pseudomonas.

Front 110

Weak acids used in eyewash solutions and used to prevent fungal growth in food and soft drinks

Back 110

Organic acids

Front 111

The antimicrobial effect of certain metals in small amounts is termed:

Back 111

Oligodynamic action

Front 112

An antimicrobial substance combines with alcohol is termed:

Back 112

Tincture

Front 113

Chlorine/ Iodine

Back 113

Halogens

Front 114

Silver Nitrate is an example of what chemical agent?

Back 114

Heavy metal

Front 115

What is the difference between disinfectant and disinfection?

Back 115

Disinfectant often causes disinfection.

Front 116

This chemical agent denatures proteins and acts as lipid solvent dissolving cell membranes. Its a surfactant and used on skin to mechanically remove microorganisms from skin prior to injection. DOES NOT STERILIZE

Back 116

Alcohol

Front 117

This chemical agent is not activated by organic matter and can be used effectively on vomits, urine, blood, and fecal matter

Back 117

Phenols: Lysol, and Amphyl are phenolic compounds.

Front 118

Ethylene oxide is used to sterilize rubber gloves, mattresses, plastics, and heat labile materials

Back 118

Gaseous Chemosterilizers

Front 119

Hydrogen peroxide disrupts protein structure and is converted into water and oxygen

Back 119

Oxidizing agents

Front 120

Zone of inhibition

Back 120

Area cleared around each disk of disinfection measured in mm.

Front 121

One or more materials that are best sterilized by ultraviolet light:

Back 121

bench tops in a transfer room, glass pipelines carrying sterile liquids (must use a type of glass that allows passage of the UV rays)

Front 122

One or more materials that are best sterilized by dry heat:

Back 122

glassware

Front 123

How does UV cause mutations?

Back 123

UV forms thymine dimers causing the cell to insert an incorrect base, leading to mutation.

Front 124

Frequently organisms isolated from the environment are pigmented, while organisms isolated from the intestine or other protected places are not. Can you provide an explanation for this?

Back 124

Organisms in the environment are exposed to the UV in sunlight and pigmentation may protect them. Organisms in the intestines of animals are not exposed to UV and therefore do not need to use resources to form pigments.

Front 125

what is tyndallization

Back 125

A method of sterilization which both vegetative and endospores are destroyed when the infusion is boiled intermittently with periods of cooling

Front 126

A molecule formed when two adjacent thymine molecules in the same strand of DNA convalently bond to one another

Back 126

Thymine dymer

Front 127

the time required for one cell to divide into two cells

Back 127

Generation time

Front 128

A curve describing the four readily distinguishable phases of microbial growth: lag, log, stationary, and death.

Back 128

Growth Curve

Front 129

A salt requiring organism able to grow in a medium containing a salt concentration high enough to inhibit other organisms.

Back 129

halophilic microbes

Front 130

microbes able to grow in environments containing high sugar concentrations

Back 130

Saccharophilic microbes