MicroExam2prep Flashcards
(416 cards)
1
Q
When we talk about Microbial growth, what do we actually mean?
A
- ) Referring to the number of cells, not size of cells.
2. ) Requirements for microbial growth are both physical and chemical
2
Q
Why is it difficult to define psychrophile, mesophile, and thermophile?
A
The optimal range of temperature for each bacterial species can fluctuate around the temperature that does work best for growth.
3
Q
Describe microorganisms that are classified into three primary groups on the basis of the preferred range of temperature.
A
- ) Psychrophiles (cold loving)
- ) Mesophiles (moderate temp loving)
- ) Thermophiles (heat-loving)
4
Q
Describe temperatures that bacterial species grow in.
A
- ) Minimum growth temperature-lowest temp. at which species would grow in.
- ) Optimum growth temperature-species grows best at
- ) Maximum growth temperature-highest temperature at which growth is possible.
5
Q
Which bacteria would you find in your fridge, spoiling your food?
A
Psychrotrophs
6
Q
What microbe is the most common and one that we work w/ in lab?
A
Mesophiles:
- ) optimum growth temp.- 25-40C
- ) optimal temp. is close to that of their hosts body
7
Q
Whats the optimal temp. for most bacteria?
A
37C
8
Q
Which bacterium would theoretically be more likely to grow at refrigerator temps? A human intestinal parasite or a soil borne plant pathogen?
A
- ) Soil borne plant pathogen (deals more w/ environment)
2. ) Human intestinal parasite would have a optimum temp. close to that of their host.
9
Q
Thermophiles
A
- ) High temps (50-60C)
- ) Sunlit soil, hot springs, hot water
- ) Can’t grow at at 45C
- ) Endospores (thermophiles) can survive in cans but not considered a health threat
10
Q
Name 2 Archaea that has an optimum growth of 80C or higher, where they live.
A
- ) Hyperthermophiles
- ) Extremethermophiles
- ) Live in hot springs associated w/ volcanic activity (sulfur)
- ) Highest record of growth is 121C near hydrothermal vents in the sea.
11
Q
Given a shallow pan and a deep pot w/ the same volume, which would cool faster?
Why?
A
- ) Shallow pan
2. ) Contains less food
12
Q
Whats the optimal pH for bacteria to grow best?
A
- ) 6.5-7.5 pH
2. ) Very few grow below pH4
13
Q
Whats the optimal pH for yeasts and molds?
A
1.) 5-6
14
Q
Acidophiles
A
1.) Tolerant of acidity
15
Q
What can you add to acids to neutralize and maintain the proper pH?
A
- ) Peptones/Amino acids
2. ) Phosphate Salts
16
Q
When microbial cell is in a solution whose concentration of solutes is higher than in the cell?
A
Environment is hypertonic to cell, cellular water will pass out through the plasma membrane to the high solute concentration. Causes plasmolysis, shrinkage of cell’s cytoplasm.
17
Q
3 types of solution environment a cell may encounter?
A
- ) Isotonic-no net movement of water occurs
- ) Hypotonic solution-water moves into the cell. If cell wall burst (osmotic lysis)
- ) Hypertonic solution-water moves out of cell, cytoplasm shrinks (plasmolysis)
18
Q
Plasmolysis
A
Shrinkage of cells cytoplasm. Growth of cell inhibited as plasma membrane pulls away from the cell wall.
19
Q
Define osmotic pressure. How can osmotic pressure be used to preserve food? Name some.
A
- ) Osmotic pressure-minimum pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane.
- ) Use of high concentrations of salts/sugars to preserve food. High concentrations of these substances create a hypertonic environment, water leaves the microbial cell (plasmolysis). Loss of water interferes w/ cell function and leads to cell death. This process resembles preservation by desiccation, in that both methods deny the cell the moisture it needs for growth.
- ) Salted fish, honey, condensed milk
20
Q
Why is osmotic pressure an important factor in microbial growth?
A
- ) Hypertonic enviroment, or an increase in salt or sugar cause plasmolysis.
- ) Microbes need a certain osmotic pressure to maintain integrity and get nutrients.
21
Q
Why are hyperthermophiles that grow at temperatures above 100C seemingly limited to oceanic depths?
A
- ) They live in environments associated w/ volcanic activity
- ) Sulfur is important in their metabolic activity
22
Q
Other than controlling acidity, what is an advantage of using phosphate salts as buffers in growth media?
A
- ) Non-toxic
2. ) Provide phosphorus (essential nutrient)
23
Q
Why might primitive civilizations have used food preservation techniques that rely on osmotic pressure?
A
- ) Salts/Sugars increase osmotic pressure
2. ) Concentrations of salt/sugars pulls water out of microbial cells and stops growth
24
Q
If bacterial cells were given a sulfur source containing radioactive sulfur (35S) in their culture media, in what molecules would 35S be found in the cells?
A
- ) Proteins
2. ) Vitamins
25
Oxygen is so pervasive in the environment that it would be difficult for a microbe to always avoid physical contact w/ it. What is the most obvious way for a microbe to avoid damage?
1. ) Presence of enzyme superoxide radicals (SOD) or superoxide anions.
2. ) Neutralizes O2 partially and microbes can tolerate it.
3. ) Formed in small amounts during respiration of organisms that use O2 as a final electron acceptor, forming water.
26
How would one determine whether a microbe is a strict anaerobe?
1. ) Growth occurs w/out presence of O2.
| 2. ) In a broth tube growth would happen at the bottom, furthest away from oxygen.
27
Identify a way in which pathogens find it advantageous to form biofilms.
1. ) Share nutrients
2. ) Sheltered from harmful factors (antibiotics, immune system, desiccation)
3. ) Transfer genetic information by conjugation
28
Why is the prevention of biofilms in healthcare so important?
1. ) 1000 times more resistant to microbicides
2. ) 70% of bact. infections involve biofilms (nonsocomial)
3. ) Form on indwelling medical equipment
29
Could Pasteur, in the 1800s, have grown rabies viruses in cell culture instead of using living animals?
1.) No b/c viruses only reproduce in a living host cell.
30
Could humans exist on chemically defined media, at least under laboratory conditions?
1. ) Yes, If the exact chemical composition is known for growth factors that an organism couldn't synthesize.
2. ) Right nutrients
3. ) Moisture
4. ) Suitable levels of 02
5. ) Proper temp.
31
Technical name for bacteria that require higher than atmospheric concentration of CO2 for growth.
1.) Capnophiles
32
In what way would an anaerobic chamber resemble the space laboratory orbiting in the vacuum of space?
1.) Materials are introduced through small doors into air-locked chambers.
33
Do nucleic acids contain sulfur?
Nope
34
Describe BSL-4 Level.
1. ) Hot zone
2. ) Only handful exist in U.S.
3. ) Sealed environment w/in large building
4. ) Atmosphere under negative pressure (so aerosols containing pathogens won't escape
5. ) Intake & Exhaust air is filtered (HEPA filters)
6. ) Exhaust air filtered twice
4. ) Space suits connected to air supply
5. ) Any material that leaves lab is rendered noninfectious
35
Describe BSL-1 Level.
1. ) Less dangerous microbes
| 2. ) Basic microbiology teaching lab
36
Describe BSL-2 Level.
1. ) Organism that present moderate risk of infection
2. ) Open lab. bench tops
3. ) Appropriate gloves
4. ) Lab coats
5. ) Face/eye protection
37
Describe BSL-3 Level.
1. ) Highly infectious airborne pathogens
2. ) Laboratory set up similar to anaerobic chamber
3. ) Lab is negatively pressurized & equipped w/ air filters
38
If a technician were working w/ pathogenic prions, how would material leaving the lab be rendered non-infectious?
?
39
Of what value are Hemolysins to pathogens?
1. ) Hemolysins consist of lipids/proteins
2. ) Cause lysis of red blood cells
3. ) Destroy the cell membrane
4. ) Blood agar (differential medium) contains red blood cells. Bacteria have lysed the red blood cells, causing clear areas around colonies. Used to identify bacterial species that destroy red blood cells
40
Is a colony formed as a result of a streaking plate always derived from a single bacterium? Why or why not?
1.) No, b/c you are inoculating from a mixed culture that contains more than one type of microbe.
41
Can you think of any reason why a colony does not grow to an infinite size, or at least fill the confines of the Petri plate?
1. ) Nutrient exhaustion
| 2. ) Over-crowded
42
Could a pure culture of bacteria be obtained by the streak plate method if there were only one desired microbe in a bacterial suspension of billions?
1.) No, you must use selective enrichment to greatly increase it's numbers before it can be isolated.
43
If the space station in Earth orbit suddenly ruptured, the humans on board would die instantly from cold and the vacuum of space. Would all the bacteria in the capsule also be killed?``
1.) No, they would freeze (lyophilization) and water would be removed due to the vacuum of space.
44
Can a complex organism, such as a beetle, divide by binary fission?
1. ) No, although binary fission and mitosis are very similar
2. ) Mitosis-mitotic spindle separates
3. ) Binary Fission-plasma membrane separates
45
If two mice started a family w/in a fixed enclosure, with a fixed food supply, would the population curve be the same as a bacterial growth curve?
1. ) Yes b/c they would be able to sustain and multiply during certain phases.
2. ) Eventually they would run out of nutrients, waste would accumulate, and harmful changes in pH would occur. They would die.
46
Why would the dilutions of 1:10,000 & 1:100,000 not be counted?
1.) TFTC colonies
47
In what instances would the pour plate method be more appropriate than the spread plate method?
1. ) Working w/ microorganisms that aren't heat-sensitive
| 2. ) When distinctive appearance of colony on the surface isn't needed for diagnostic purposes
48
Why is it difficult to measure the growth of a filamentous mold isolate by the growth plate method?
1. ) Filamentous mold is usually grown on saw dust or organic materials
2. ) Hyphae (thin, stringy) branch in all directions and interlace
3. ) No distinct separation which would make it difficult to measure or count
49
Could you make a pour plate in the usual petri dish w/ a 10ml of inoculum? Why or why not?
1.) You could but it wouldn't produce a countable plate.
50
Under what circumstances is the MPN (most probable number method) used to determine the number of bacteria in a sample?
1. ) When microbes being counted will not grow on solid media
2. ) Useful when growth of bacteria in a liquid medium is used to identify the microbes.
51
Direct microscopic count of bacteria w/ a Petroff-Hausser cell counter is often used to estimate bacterial population in dairy products. Why?
1. ) No incubation time required
2. ) Reserved for applications that time is primary consideration
3. ) Large numbers of bacteria in uncultured products give evidence of unsanitary conditions, no matter what type of organisms are present or whether they are viable (living) cells
52
Why is turbidity more useful in measuring contamination of liquids by large numbers, rather than small numbers, of bacteria?
1.) Large numbers are needed to make a suspension turbid enough to be read on a spectrophotometer
53
What are the requirements for growth?
1. ) Growth of a population is an increase in the number of cells
2. ) Requirements for microbial growth are both physical and chemical
54
Do all organisms require a carbon source?
Yes
55
Chemoheterotrophs use a?
1.) Organic molecule
56
Autotrophs typically use a?
1.) Carbon dioxide
57
Nitrogen is needed for protein and nucleic acid synthesis? T or F?
1.) True
58
Nitrogen can be obtained from?
1. ) Decomposition of proteins
2. ) NH4+ or NO3-
3. ) Some bacteria are capable of nitrogen (N2) fixation
59
On the basis of oxygen requirements, organisms are classified as?
1. ) Obligate aerobes
2. ) Facultative anaerobes
3. ) Obligate anaerobes
4. ) Aerotolerant anaerobes
5. ) Microaerophiles
60
Aerobes, facultative anaerobes, and aerotolerant anaerobes must have the enzymes?
1. ) Superoxide dismutase
2. ) Catalase
3. ) Peroxidase
61
List some chemicals required for microbial growth?
1. ) Sulfur
2. ) Phosphorus
3. ) Trace elements
4. ) Organic growth factors (some microorganisms)
62
Describe chemically defined media.
1.) Exact chemical composition is known
63
Describe complex media.
1.) Exact chemical composition varies slightly from batch to batch
64
Reducing media chemically?
1.) Removes molecular oxygen (02) that might interfere w/ the growth of anaerobes.
65
Petri plates can be incubated in an?
1. ) Anaerobic jar
2. ) Anaerobic chamber
3. ) OxyPlate
66
Some parasitic and fastidious bacteria must be cultured in?
1. ) Living animals
| 2. ) Cell cultures
67
CO2 incubators or candle jars are used to grow bacteria that require an increased?
1.) C02 concentration
68
By inhibiting unwanted organisms w/ salts, dyes, or chemicals, selective media allow growth of only?
1.) The desired microbes
69
Differential media are used to?
1.) Distinguish different organisms
70
An enrichment culture is used to?
1.) Encourage the growth of a particular microorganisms in a mixed culture
71
A colony is a visible mass of microbial cells that theoretically arose from?
1.) One cell
72
Pure cultures are usually obtained by?
1.) Streak plate method
73
Microbes can be preserved for long periods of times by?
1. ) Deep freezing
| 2. ) Lyophilization (freeze drying)
74
What is binary fission?
1. ) Reproductive method
| 2. ) Single cell divides into two identical cells
75
Other ways bacteria reproduce besides binary fission?
1. ) Budding
2. ) Aerial spore formation
3. ) Fragmentation
76
The time required for a cell to divide or a population to double is known as?
1.) Generation
77
Bacterial division occurs according to a?
1.) Logarithmic progression (two cells, four cells, eight cells, so on
78
During the lag phase?
1. ) Little or no change in number of cells
| 2. ) Metabolic activity high
79
During the log phase?
1.) Bacteria multiply at the fastest rate under the conditions provided
80
During the stationary phase?
1.) There is an equilibrium between cell division and death
81
During the death phase?
1.) Number of deaths exceeds the number of new cells formed
82
A heterotrophic plate count reflects the number of?
1. ) Viable microbes
2. ) Assumes each bacterium grows into a single colony
3. ) Reported as number of colony-forming units (CFU)
83
A plate count may be done by?
1. ) Pour plate method
| 2. ) Spread plate method
84
In filtration, bacteria are retained on the surface of? And transferred to?
1. ) Membrane filter
| 2. ) Culture medium to grow and be counted
85
The most probable number method (MPN) can be used for microbes that will grow in? It is a______estimation?
1. ) Liquid medium
| 2. ) Statistical estimation
86
In a direct microscopic count, the microbes in a measured volume of a bacterial suspension are?
1.) Counted w/ use of specially designed slide
87
A spectrophotometer is used to determine turbidity by measuring?
1.) Amount of light that passes through a suspension of cells
88
An indirect way of estimating bacterial numbers is measuring?
1.) Metabolic activity of the population (ex. acid production or oxygen consumption)
89
For filamentous organisms such as fungi, measuring dry weight is a convenient method of?
1.) Growth measurement
90
Macronutrients are often listed as (CHONPS). What does each letter indicate? Why are they needed by the cell?
1. ) Carbon-synthesis of molecules that make up a living cell
2. ) Hydrogen-source of electrons and component or organic molecules
3. ) Oxygen-component of organic molecules; electron acceptor in aerobes
4. ) Nitrogen-component of amino acids
5. ) Phosphorus-in phospholipids and nucleic acids
6. ) Sulfur-in some amino acids
91
Nitrogen and phosphorus are added to beaches following an oil spill encourage the growth of natural oil degrading bacteria. Explain why the bacteria do not grow if nitrogen and phosphorus are not added.
1. ) Petroleum can meet the carbon and energy requirements for an oil-degrading bacterium.
2. ) Nitrogen and phosphate are usually not available in large quantities.
3. ) Nitrogen and phosphate are essential for making proteins, phospholipids, nucleic acids, and ATP.
92
The usual definition of sterilization is the removal or destruction of all forms of microbial life; how could there be practical exceptions to this simple definition?
Prions have a high resistance to all forms of sterilization; sterilization implies to the absence of prions. Some endospores of a number of thermophilic bacteria are capable of causing food spoilage but not human disease and are resistant to heat. If present, they'll survive, but this survival is of no practical consequence as they will not grow at normal food storage temperatures.
93
If canned foods in a supermarket were incubated above 45C significant food spoilage occur. T or F?
True
94
Give examples where complete sterilization is often not required in certain settings.
The body's defenses can cope w/ a few microbes entering a surgical wound, a drinking glass or fork requires only enough microbial control to prevent the transmission of possibly pathogenic microbes from one person to another.
95
What are several factors that influence the effectiveness of antimicrobial treatments?
The number of microbes, environmental influences, time of exposure, microbial characteristics.
96
How is it possible that a solution containing a million bacteria would take longer to sterilize than one containing a half-million bacteria.
The more microbes there are to begin w/ the longer it takes to eliminate the entire population.
97
Would a chemical microbial control agent that affects plasma membranes affect humans?
A microbial agent that targets the plasma membrane of the microorganism would not be advised because humans also have a plasma membrane. For this reason, it is important to develop a microbial agent that targets components of the microorganism that are not present in the host cell. For example, penicillin is an antibiotic that targets the cell well. Since the cell wall is not present in human cells, penicillin causes no damage to the host cell.
98
Sterilization in an autoclave at a pressure of about 15 psi (121C) will kill all organisms and eventually endospores after about 15 minutes, but will not kill?
Prions
99
What should be used instead of aluminum foil to wrap items so that steam may sterilize them?
Paper
100
How is microbial growth in canned foods prevented?
By heating, it denatures the proteins in the food which render the bacteria harmless.
101
Why would a can of pork take longer to sterilize at a given temperature than a can of soup that also contained pieces of pork?
Solid foods heat unevenly because of the uneven distribution of moisture.
102
What is the connection between the killing effect of radiation and hydroxyl radical forms of oxygen?
These radicals are produced from ionizing radiation that take electrons from other molecules.
103
How might increased UV radiation impact the earth's ecosystems?
Exposure to higher amounts of UV radiation could have serious impacts on human beings, animals and plants, such as the following: harm to human health, adverse impacts on agriculture, forestry and natural ecosystems, damage to marine life, damage to an animals health, and damage to materials.
104
Pseudomonas aeruginosa, is a gram negative bacterium that is very resistant to triclosan, as well as to many other antibiotics and disinfectants. T or F?
True
105
Some lozenges intended to alleviate the symptoms of a sore throat contain phenol. Why include this ingredient?
Phenol can kill surface germs, thereby keeping the invaders in check until your body has a chance to build up its resistance
106
Are quats more effective against gram-positive or gram-negative bacteria?
Gram-positive
107
Why a tincture of Zephiran more effective than the aqueous solution?
A tincture of Zephiran kills about 85% percent compared to an aqueous solution that kills at 40% in two minutes b/c the tincture of Zephiran has a higher amount of ethanol and isopropanol in it.
108
What are the two functions of Nitrite in meat?
To preserve the red color of meat and to prevent germination and growth of any botulism endospores that might be present.
109
If you wanted to disinfect a surface contaminated by vomit and a surface contaminated by a sneeze, why would your choice of disinfectant make a difference?
In these situations, organic material would be present that would inhibit the effectiveness of the disinfectant.
110
Which is more likely to be used in a medical clinic laboratory, a use-dilution test or a disk-diffusion test?
Disk-diffusion test. Because this is what is used to measure the effectiveness of specific antibiotics on certain microbes.
A use-dilution test would be more appropriate in industrial uses because it measures what is the lowest amount of chemical needed in a solution to effectively kill microbes.
111
Why is alcohol effective against some viruses and not other?
It does not kill endospores or non enveloped viruses. The mechanism of alcohol is protein denaturation but it can also disrupt membranes and dissolve many lipids, including the lipid component of enveloped viruses. It requires water b/c denaturation requires it and alcohol by itself will evaporate rapidly leaving no residue.
112
Is Betadine an antiseptic or a disinfectant when it is used on skin?
An antiseptic. Anything that is applied to the skin will be an antiseptic and anything applied to objects is considered a disinfectant.
113
What characteristics make surface-active agents attract to the dairy industry?
Acid-Anionic Sanitizers: important in cleaning dairy utensils and equipment; Non-toxic; non-corrosive; and fast acting.
114
What chemical disinfectants can be considered sporicides?
Phenols; Glutaraldehyde; B-Propiolactone; Ethylene oxide ;Peroxy acids
115
What chemicals are used to sterilize?
Ethylene Oxide is the gas most frequently used for sterilization. Chlorine dioxide as well.
116
Why are viruses w/ lipid containing envelopes relatively susceptible to certain biocides?
B/c some biocides are lipid-soluble and are more likely to be effective against enveloped viruses.
117
The presence or absence of endospores has an obvious effect on microbial control, but why are gram-negative bacteria more resistant to chemical biocides than gram-positive bacteria?
Gram-negative bacteria contain an external lipopolysaccharide layer. There are porins in the wall and they are highly selective of molecules that they permit to enter the cell.
118
Sterilization is the process of?
Removing and destroying all microbial life on an object
119
Commercial sterilization is a heat treatment of canned foods that destroys__________endospores?
C. botulinum
120
Disinfection is the process of?
Reducing or inhibiting microbial growth n a nonliving surface
121
Antisepsis is the process of?
Reducing or inhibiting microorganisms on living tissues
122
The suffix -cide means?
to kill
123
The suffix -stat means?
to inhibit
124
Sepsis is?
bacterial contamination
125
Bacterial populations subjected to ______or_______usually die at a constant rate.
heat or antimicrobial chemicals
126
Such a death curve, when plotted logarithmically, shows this constant death rate as a?
Straight line
127
The time it takes to kill a microbial population is proportional to?
The number of microbes
128
Microbial species and life cycle phases have different susceptibilities to____________and___________.
Physical and chemical control agents.
129
Organic matter may interfere with__________and___________?
Heat treatments and chemical control agents
130
Longer exposure to_______heat can produce the_______effect as shorter time at higher heat.
Lower, same
131
The control of microbial growth can________infections and food_________.
prevent, spoilage
132
The susceptibility of the plasma membrane is due to its____and________components.
Lipid, protein
133
Certain chemical control agents damage the plasma membrane by?
Altering it permeability
134
Some microbial control agents damage cellular proteins by?
Breaking hydrogen bonds and covalent bonds
135
Other agents interfere with DNA and RNA and?
Protein synthesis
136
How does moist heat kill microbes?
Denatures enzymes
137
Describe thermal death point (TDP)
Lowest temperature at which all the microbes in a liquid culture will be killed in ten minutes.
138
Describe thermal death time (TDT)
The length of time required to kill all bacteria in a liquid culture at a given temperature.
139
Describe decimal reduction time (DRT)
Length of time in which 90% of a bacterial population will be killed at a given temperature.
140
Boiling at (100C) kills______and_______within 10 minutes.
Vegetative cells, viruses
141
Autoclaving (steam under pressure)
Most effective method of moist heat sterilization Steam must directly contact the material to be sterilized.
142
In HTST pasteurization, a______temperature is used for a______time to destroy pathogens w/out altering the flavor of food.
High temperature for a short time (72C for 15secs)
143
Ultra High Temperature (UHT) treatment (140C for 4 secs) is used to sterilize?
Dairy products
144
Methods of dry heat sterilization include?
Direct flaming, incineration, hot-air sterilization.
145
Dry-heat kills by?
Oxidation
146
Different methods that produce the same effect (reduction in microbial growth) are called?
Equivalent treatments
147
What is filtration?
Passage of a liquid or gas through a filter w/ pores small enough to retain microbes
148
Microbes can be removed from air by?
High-efficiency particulate air (HEPA) filters.
149
Membrane filters composed of cellulose esters are commonly used to filter out?
Bacteria, viruses, and large proteins.
150
Does the effectiveness of low temperatures depend on the particular microorganism and the intensity of the application?
Yes
151
Most microorganisms________reproduce at ordinary refrigerator temperatures (0-7C).
Do not
152
Many microbes________at subzero temperatures but do not grow.
Survive
153
High pressure______proteins in vegetative cells.
Denature
154
In the absence of water, microorganisms_________grow but can remain viable.
Cannot
155
Can viruses and endospores resist desiccation?
Yes
156
Microorganisms in high concentrations of salts and sugars undergo?
Plasmolysis
157
Molds and yeasts are more capable than bacteria of growing in materials with?
Low moisture or high osmotic pressure
158
The effects of radiation depend on its?
Wavelength, intensity and duration
159
List forms of ionizing radiation
Gamma rays, x-rays, high energy electron beams
160
Ionizing radiation
Has a high degree of penetrate and exerts its effect primarily by ionizing water and forming highly reactive hydroxyl radicals.
161
Ultraviolet (UV) radiation
From of non ionizing radiation, has a low degree of penetration and causes cell damage by making thymine dimers in DNA that interfere w/ DNA replication; the most effective germicidal wavelength is 260nm.
162
Microwaves can kill microbes___________as materials get hot.
Indirectly
163
Chemical agents are used on living tissue as_________and on inanimate objects as_____________?
Antiseptics, disinfectants.
164
Do chemical agents achieve sterility?
Very few do
165
Should careful attention be paid to the properties and concentration of the disinfectant to be used?
YES
166
Should you consider the presence of organic matter, degree of contact with microorganism, and temperature when effectively using a disinfectant?
YES
167
When evaluating a disinfectant, the use-dilution test, bacterial survival in the manufacturer's recommended dilution of a disinfectant is?
Determined
168
Can viruses, endospore-forming bacteria, mycobacteria, and fungi can also be used in the use-dilution test.
Yes
169
In the disk-diffusion method, a disk of filter paper is soaked w/ a chemical and placed on an inoculated agar plate; a zone of inhibition indicates?
Effectiveness
170
Phenolics exert their action by injuring the?
Plasma membrane
171
Bisphenols such as triclosan and hexachlorophene are widely used in?
Household products
172
Biguanides damage?
Plasma membrane of vegetative cells
173
Some halogens (iodine and chlorine) are used?
Alone or as components of inorganic or organic solutions
174
Iodine may combine with certain amino acids to?
Inactivate enzymes and other cellular proteins
175
Iodine is available as a tincture (in solution w/ alcohol) or as an?
Iodophor (combined w/ an organic molecule)
176
The germicidal action of chlorine is based on the formation of?
Hypochlorous acid when chlorine is added to water.
177
Alcohols exert their action by?
Denaturing proteins and dissolving lipids
178
__________enhance the effectiveness of other antimicrobial chemicals?
Tinctures
179
Aqueous ethanol (60-95%) and isopropanol are used as?
Disinfectants
180
Silver, mercury, copper, and zinc are used as?
Germicides
181
How do silver, mercury, copper, and zinc exert their antimicrobial action through oligodynamic action?
When heavy metal ions combine w/ sulfhydryl (-SH) groups, proteins are denatured.
182
Surface-active agents; such as soaps and detergents,_______the surface tension among molecules of a liquid.
Decrease
183
Soaps have_______germicidal action but assist in removing microorganisms.
Limited
184
Acid-anionic detergents are used to clean?
Dairy Products
185
Quats are______detergents attached to NH4+.
Cationic
186
By disrupting plasma membranes, quats allow cytoplasmic constituents to?
Leak out of the cell
187
SO2, sorbic acid, benzoic acid, and propionic acid_____fungal metabolism and are used as________?
Inhibit and food preservatives
188
Nitrate and nitrite salts prevent germination of_________in meats.
C. botulinum endospores
189
Aldehydes such as formaldehyde and glutaraldehyde exert their antimicrobial effect by?
Inactivating proteins and are the most effective chemical disinfectants.
190
Nisin and natamycin are antibiotics used to?
Preserve food (cheese)
191
Ethylene oxide is a gas most frequently used for?
Sterilization (penetrates most materials and kills all microorganisms by protein denaturation)
192
Free radicals in plasma gases are used to?
Sterilize plastic instruments
193
Supercritical fluids, which have properties of liquid and gas, can?
Sterilize at low temperatures.
194
Hydrogen peroxide, peracetic acid, benzoyl peroxide, and ozone exert their antimicrobial effect?
By oxidizing molecules inside cells.
195
Gram-negative bacteria are generally more resistant than Gram-positive bacteria to?
Disinfectants and antiseptics
196
Mycobacteria, endospores, and protozoan cysts and oocysts are very resistant to.
Disinfectants and antiseptics.
197
Nonenveloped viruses are generally more resistant than enveloped viruses to?
Disinfectants and antiseptics
198
Prions are resistant to?
Disinfection and autoclaving.
199
Most resistant microorganism and least resistant.
Prions and viruses w/ lipid envelopes
200
Phenol
Disrupts plasma membrane, denatures enzymes, rarely used, and is known for its irritating qualities and disagreeable odor.
201
Phenolics
Disrupts plasma membrane, denatures enzymes. Used on environmental surfaces, instruments, skin, and mucous membranes. Derivatives of phenol that is even reactive in the presence of organic material.
202
Bisphenols
Probably disrupt plasma membrane and is found in disinfectant hand soaps and skin lotions. Triclosan is common example and bisphenols are most effect against gram-positives.
203
Biguanides (Chlorhexidine)
Disrupts plasma membrane, skin disinfection, especially for surgical scrubs. Bactericidal to gram-positives and gram-negatives; nontoxic, persistent.
204
Osmotic pressure
Plasmolysis, results in loss of water from microbial cells, used in food preservation.
205
Desiccation
Disrupts metabolism, involves removing water from microbes, primarily bacteriostatic, used in food preservation.
206
High pressure
Alteration of molecular structure of proteins and carbohydrates. Preserves of colors, flavors, nutrient values. Used in fruit juice.
207
Cold (refrigeration, deep-freezing, lyophilization)
Decreased chemical reactions and possible changes in proteins. Either has a bacteriostatic effect, preserving, or long-term preservation of microbial cultures. Used for food, drug, and culture preservation.
208
What is a gene? What is an open-reading frame?
Gene-segments of DNA (except in some viruses, in which they are made of RNA) that code for functional products.
Open-reading frame- continuous stretch of DNA beginning with a start codon, usually methionine (ATG), and ending with a stop codon
209
Give a clinical application of genomics.
It was used to track West Nile Virus
210
Why is the base paring in DNA important?
Without complimentary base pairing their would be no structure of a DNA
211
What is the advantage of semiconservative replication?
Each offspring cell gets one strand of DNA from the parent cell, which survived to reproduce
212
Why is one strand upside down relative to the other strand? Why can't both strands face up the same way?
Carbon 1′ of each sugar must face each other for base pairing causing the antiparallel arrangement. The nucleotide bases would not face each other if the strands were parallel
213
What is genetics?
The study of what genes are, how they carry information, how they are replicated and passed to subsequent generations or other organisms.
214
How does DNA in cells exists?
As a double stranded helix: the two strands are held together by hydrogen bonds between specific nitrogenous base pairs; AT and CG.
215
A gene is a?
Segment of DNA, a sequence of nucleotides, that encodes a functional product, usually a protein.
216
The DNA in a cell is____________before it divides, so each offspring cell receives the same genetic information.
Duplicated
217
Genotype is the?
Genetic composition of an organism, its entire complement of DNA.
218
Phenotype is the?
Expression of the genes: the proteins of the cell and the properties they confer on the organisms.
219
DNA in a chromosome exists as one long___________associated with various proteins that regulate genetic activity.
Double Helix
220
Genomics is the molecular characterization of
Genomes
221
Information contained in the DNA is transcribed into RNA and translated into?
Proteins
222
During DNA replication, the two strands of the double helix separate at the replication fork, and each strand is used as a template by DNA polymerases to synthesize two new strands of DNA according to the rules of?
Nitrogenous base pairing.
223
The result of DNA replication is two new strands of DNA, each having a sequence complementary to one of the?
Original strands
224
B/c of each double-stranded DNA molecule contains one original and one new strand, the replication process is called?
Semiconservative.
225
DNA is synthesized in one direction designated__________. At the replication fork, the leading strand is synthesized__________and the lagging strand___________.
5'-3', continuously, discontinuously
226
DNA polymerase proofreads new molecules of DNA and removes mismatched bases before continuing?
DNA synthesis
227
Each daughter bacterium receives a chromosome that is virtually________to the parent's.
Identical
228
During transcription, the enzyme RNA polymerase synthesizes a strand of RNA from one strand of double stranded DNA, which serves as a_______?
Template
229
RNA is synthesized from nucleotides congaing the bases A,C,G, and U, which pair with the bases of the DNA strand being_________.
Transcribed
230
RNA polymerase binds the promoter; transcription begins at AUG; the region of DNA that is the end point of transcription is the terminator; RNA is synthesized in the______direction.
5'-3'
231
Translation is the process in which the information in the nucleotide base sequence of mRNA is used to dictate the amino acid sequence of a?
Protein
232
The mRNA associates with ribosomes, which consist of?
rRNA and proteins
233
Three-Base segments of mRNA that specify amino acids are called?
Codons
234
The genetic code refers to the relationship among the______of DNA, the corresponding_______of mRNA, and the__________for which the codons are made.
Nucleotide base sequence, codons, amino acids.
235
The genetic code is degenerate; that is, most amino acids are coded for by more than?
One codon
236
Specific amino acids are attached to molecules of _________. Another portion of__________has a base triplet called an anticodon.
tRNA, tRNA
237
The base pairing of codon and anticodon at the ribosome results in specific amino acids being brought to the site of?
Protein synthesis
238
The ribosome moves along the mRNA strand as amino acids are joined to form a growing polypetide; mRNA is read in the?
5'-3'
239
Translation ends when the ribosome reaches a______on the mRNA.
Stop Codon
240
Regulating protein synthesis at the gene level is energy-efficient b/c proteins are?
Synthesized as needed
241
Constitutive enzymes produce products at a_______.
Fixed rate
242
For gene regulatory mechanisms, the control is aimed at?
mRNA synthesis
243
When cells are exposed to a particular end product, the synthesis of enzymes related to that product is?
Repressed
244
IN the presence of certain chemical (inducers), cells synthesize more enzymes. This process is called?
Induction
245
In bacteria, a group of coordinately regulated structural genes with related metabolic functions, plus the promoter and operator sites that control their transcription are called an?
Operon
246
In the operon model for an inducible system, a regulatory gene codes for the?
Repressor protein
247
When the inducer is absent, the repressor binds to the operator, and no?
mRNA is synthesized
248
When the inducer is present, it binds to the repressor so that it cannot bind to the operator; thus, mRNA is made, and enzyme synthesis is?
Induced
249
In repressible systems, the repressor requires a corepressor in order to bind to the operator site; thus, the corepressor controls?
Enzyme synthesis
250
Transcription of structural genes for catabolic enzymes is induced by the absence of_______? Cyclic AMP and CRP must bind to a promoter in the presence of an alternative___________?
Glucose, carbohydrate
251
Methylated nucleotides are not_______in epigenetic control.
Transcribed
252
MicroRNAs combine with mRNA; the resulting double-stranded RNA is?
Destroyed
253
A mutation is a change in the_________of DNA; that causes a change in the product coded for by the mutated gene.
Nitrogenous base sequence
254
Many mutations are?
Neutral, some are disadvantageous, and others beneficial
255
A base substitution occurs when one base pair in DNA is replaced with a?
Different base pair
256
Alterations in DNA can result in missense mutation which cause_______________? Or nonsense mutations which create________?
Amino acid substitutions, stop codons
257
In a frameshift mutation?one or a few base pairs are deleted or added to DNA.
One or a few base pairs are deleted or added to DNA.
258
Mutagens are agents in the environment that cause?
Permanent changes in DNA
259
Spontaneous mutations occur w/out the presence of any?
Mutagen
260
Chemical mutagens include?
Base pair mutagens, nucleoside analogs, and frameshift mutagens.
261
Ionizing radiation causes the formation of____and free_____that react w/ DNA; base substitutions or breakage of sugar phosphate backbone results.
Ions, free radicals
262
Ultraviolet radiations is________; it causes bonding between adjacent thymines.
Nonionizing
263
Damage to DNA caused by UV radiation can be repaired by enzymes that?
Cut out and replace the damaged portion of DNA
264
Light-repair enzymes repair thymine dimers in the presence of?
Visible light
265
Mutation rate is the probability that a gene will?
Mutate when a cell divides, the rate is expressed as 10 to the negative power
266
Mutations usually occur?
Randomly along a chromosome
267
A low rate of spontaneous mutations is beneficial in providing the?
Rate of genetic diversity need for evolution
268
Mutants can be detected by?
Selecting or testing for an altered phenotype
269
Positive selection involves?
The selection of mutant cells and the rejection of non mutated cells.
270
Replica plating is used for negative selection to?
Detect, for example autotrophs that have nutritional requirements not posed by the parent (non mutated) cell.
271
The Ames test is a relatively inexpensive and rapid test for identifying possible chemical__________?
Carcinogens
272
The Ames test assumes that a mutant cell can?
Revert to a normal cell in the presence of a mutagen and that many mutagens are carcinogens.
273
DNA recombination, the rearrangement of genes from separate groups of genes, usually involves_____from different organisms; it contributes to genetic diversity.
DNA
274
In crossing over, genes from two chromosomes are_____into one chromosome containing some genes from each original chromosome
Recombined
275
Vertical gene transfer occurs during________when genes are passed from an organism to offspring.
Reproduction
276
Horizontal gene transfer in bacteria involves a______of the cell's DNA being transferred from donor to recipient.
Portion
277
When some of the donor's DNA has ben integrated into the recipient's DNA, the resultant cell is called a?
Recombinant
278
During this process, genes are transferred from one bacterium to another as "naked" DNA in solution. This also occurs naturally among a few genera of bacteria.
Transformation
279
This process requires contact between living cells.
Conjugation in Bacteria
280
One type of genetic donor cell is an F+; recipient cells are F-. F cells contain plasmids called________; these are transferred to the F- cells during conjugation.
F Factors
281
When the plasmid becomes incorporated into the chromosome, the cell is called an__________cell
Hfr (high frequency of recombination)
282
During conjugation, an Hhf cell can transfer________to an F-cell. Usually, the Hfr chromosome breaks before its fully transferred.
Chromosomal DNA
283
In this process, DNA is passed from one bacterium to another in a bacteriophage and is then incorporated into the recipient's DNA.
Transduction in Bacteria
284
In generalized transduction, any bacterial cells can be?
Transferred
285
Plasmids are self-replicating circular molecules of_______, carrying genes that re not usually essential for the cell's survival.
DNA
286
There are several types of plasmids, including?
Conjugative plasmids, dissimilation plasmids, plasmids carrying genes for toxins or bacteriocins, and resistance factors.
287
Transposons are small segments of DNA that can?
Move from one region to another region of the same chromosome or to a different chromosome or plasmid.
288
Transposons are found in?
Chromosomes, plasmids, genetic material of viruses.
289
Transposons vary from simples to_______?
Complex
290
Complex transposons can carry any type of gene, including antibiotic resistance genes, and are thus a natural mechanism for?
Moving genes from one chromosome to another.
291
Diversity is the precondition for?
Evolution
292
Genetic mutation and recombination provide a_______of organisms, and the process of_________allows the growth of those best adapted to a given environment.
Diversity, natural selection.
293
Phylogeny is the evolutionary history of a group of?
Organisms
294
The taxonomic hierarchy shows ___________, or phylogenetic, relationships among organisms.
Evolutionary
295
Bacteria were separated into the Kingdom Prokaryotae in?
1968
296
Living organisms were divided into______kingdoms in 1969.
5
297
Living organisms are currently classified into three domains. A domain can be divided into a?
Kingdom
298
In this system, plants, animals, and fungi belong to the Domain?
Eukarya
299
Bacteria (w/ peptidoglycan) form a?
Second Domain
300
Archaea (w/ unusual cell walls) are place in the?
Domain Archaea
301
Organisms are grouped into taxa according to________relationships (from a common ancestor).
Phylogenetic
302
Some of the information for Eukaryotic relationships is obtained from the?
Fossil record
303
Prokaryotic relationships are determined by?
rRNA sequencing
304
According to scientific nomenclature, each organism is assigned two names, or a binomial?
Genus and a specific epithet, or species
305
Rules for assigning names to bacteria are established by the?
International Committee on Systematics of Prokaryotes
306
Rules for naming fungi and algae are published in the?
International Code of Botanical Nomenclature
307
Rules for naming protozoa are found in the?
International Code of Zoological Nomenclature
308
A eukaryotic species is a group of organisms that interbreed w/ each other but?
Do not breed w/ individuals of another species
309
Similar species are grouped into a?
a genus; similar genera are grouped into a family; families, into an order; orders, into a class; classes, into a phylum; phyla, into a kingdom; and kingdoms, into a domain.
310
Bergey's Manual of Systematic Bacteriology is the standard reference on?
Bacterial classification
311
A group of bacteria derived from a single cell is called a?
Strain
312
Closely related strains constitute a?
Bacterial species
313
Eukaryotic organisms may be classified into the?
Kingdom Fungi, Plantae, or Animalia
314
Protists are mostly_______ organisms; these organisms are currently being assigned to kingdoms.
Unicellular
315
Fungi are absorptive chemoheterotrophs that develop from?
Spores
316
Multicellular photoautotrophs are placed in the?
Kingdom Plantae
317
Multicellular ingestive heterotrophs are classified as?
Animalia
318
Viruses are not placed in a kingdom. They are not composed of_______and cannot grow w/out a host_____.
Cell
319
A viral species is a population of viruses w/ similar characteristics that occupies a particular?
Ecological niche
320
Bergey's Manual of Determinative Bacteriology is the standard reference for laboratory identification of?
Bacteria
321
Morphological characteristics are useful in identifying microorganisms, especially when aided by?
Differential Staining techniques
322
The presence of various enzymes, as determined by biochemical test, is used in?
Identifying bacteria and yeasts
323
Serological tests, involving the reactions of microorganisms w/ specific antibodies, are useful in determining the identity of strains and species, as well as relationships among organisms. Give examples of serological tests.
ELISA and Western blotting.
324
Phage type is the identification of bacterial species and strains by determining their?
Susceptibility to various phages
325
Fatty acid profiles can be used to?
Identify some organisms
326
Flow cytometry measures_______and_______characteristics of cells.
Physical and chemical
327
The percentage of GC base pairs in the nucleic acid of cells can be used in the?
Classification of organisms.
328
The number and sizes of DNA fragments, or DNA fingerprints, produced by restriction enzymes are used to determine?
Genetic similarities
329
NAATs can be used to amplify a small amount of microbial DNA in a sample. The presence or identification of an organism is indicated by?
Amplified DNA
330
Single strand of DNA, or of DNA, and RNA, from related organisms will hydrogen bond to form a double-stranded molecule; this bonding is called?
Nucleic acid hybridization
331
Souther blotting, DNA chips, and FISH are exempts of?
Nucleic acid hybridization techniques
332
The sequence of bases in ribosomal RNA can be used in the classification of?
Organisms
333
Dichotomous keys are used for the identification of organisms. Cladograms show?
Phylogenetic relationships among organisms.
334
Biotechnology is the use of?
Microorganisms, cells, or cell components to make a product
335
Closely related organism can exchange_________in natural recombination.
Genes
336
Genes can be transferred among unrelated species via laboratory manipulation, called?
Recombinant DNA technology
337
Recombinant DNA is DNA that has been artificially manipulated to?
Combine genes from two different sources
338
A desired gene is inserted into a DNA vector, such as a?
Plasmid or viral genome
339
Large quantities of the gene product can be harvested from the?
Clone
340
Microbes w/ desirable traits are selected for?
Culturing by artificial selection
341
Mutagens are used to cause?
Mutations that might result in a microbe w/ desirable traits.
342
Site-directed mutagenesis is used to?
Change a specific codon in a gene
343
Prepackaged kits are available for?
rDNA techniques
344
A restriction enzyme recongnizes and cuts only one particular nucleotide sequence in?
DNA
345
Some restriction enzymes produce sticky ends, short stretches of single-stranded DNA at the ends of?
DNA fragments
346
Fragments of DNA produced by the same restriction enzyme will?
Spontaneously join by base pairing
347
DNA ligase can covalently link the?
DNA backbones
348
Shuttle vectors are_______that can exist in several different species.
Plasmids
349
A plasmid containing a new gene can be inserted into a cell by?
Transformation
350
A virus containing a new gene can insert the gene into a?
Cell
351
The polymerase chain reaction is used to make?
Multiple copies of a desired piece of DNA enzymatically
352
PCR can be used to increase the amount of DNA in samples to detectable levels. This may allow?
Sequencing of genes, the diagnosis of genetic disease, or the detection of viruses.
353
Cells can take up naked DNA by?
Transformation
354
Chemical treatments are used to make cells are are not naturally competent to take up?
DNA
355
Pores made in protoplasts and animal cells by electric current in the process of electroporation can provide?
Entrance for new pieces of DNA
356
Protoplast fusion is the?
Joining of cells whose cell walls have been removed
357
Foreign DNA can be introduce into plant cells by?
Shooting DNA coated particles into the cells
358
Foreign DNA can be injected into animal cells by?
Using a fine glass micropipette
359
Genomic libraries can be made by?
Cutting up an entire genome w/ restriction enzymes and inserting the fragments into bacterial plasmids or phages
360
Complementary DNA (cDNA) made from mRNA by reverse transcription can be?
Cloned in genomic libraries
361
Synthetic DNA can be made in vitro by a?
DNA synthesis machine
362
Antibiotic resistance markers on plasmid vectors are used to?
Identify cells containing the engineered vector by direct selection
363
In blue-white screening, the vector cottons the genes for?
ampR and B-galactosidase
364
The desired gene is inserted into the B-galactosidase gene site, destroying the?
Gene
365
Clone containing the recombinant vector will be resistant to________and unable to hydrolyze X-gal (white colonies).
Ampicillin
366
Clones containing the vector w/out the new gene will be?
Blue
367
Clones lacking the vector will?
Not grow
368
Clones containing foreign DNA can be tested for the?
Desired gene product
369
A short piece of labeled DNA called a DNA probe can be used to?
Identify clones carrying the desired gene
370
E. Coli is used to produce proteins using_______b/c E. coli is easily grown and its genomics are well understood.
rDNA
371
Efforts must be made to ensure that E. coli's endotoxin does not?
Contaminate a product intended for human use
372
To recover the product, E coli must be lysed, or the gene must be linked to a gene that produces a?
Naturally secreted protein
373
Yeasts can be genetically modified and are likely to secrete a gene product?
Continously
374
Genetically modified mammalian cells can be grown to produce?
Proteins such as hormones for medical use
375
Genetically modified plant cells can be grown and used to produce?
Plants w/ new properties
376
Cloned DNA is used to produce products, study the cloned DNA, and?
Alter the phenotype of an organism
377
Synthetic genes linked to the B-galactosidase gene (lacZ) in plasmid vector were inserted into E. coli, allowing E. coli to produce and secrete the?
Two polypeptides used to make human insulin
378
Cells and viruses can be modified to produce a?
Pathogen's surface protein, which can be used as a vaccine
379
DNA vaccines consist of
rDNA cloned in bacteria
380
Gene therapy can be used to cure?
Genetic diseases by replacing the defective or missing gene
381
RNAi may be useful to prevent?
Expression of abnormal protein
382
Nucleotide sequences of the genomes over 1000 organisms, including humans, have been?
Completed, this leads to determining the proteins produced in a cell
383
DNA can be used to increase understanding of DNA, for genetic fingerprinting, and?
For gene therapy
384
DNA sequencing machines are used to?
Determine nucleotide base sequence of restriction fragments in shotgun sequencing
385
Bioinformatics is the use of computer application to study genetic data; proteomics is the study of a cell's?
Proteins
386
Southern blotting can be used to?
Locate a gene in a cell
387
DNA probes can be used to quickly identify a pathogen in?
Body tissue or food
388
Forensic microbiologists use DNA fingerprinting to identify the?
Source of bacterial or viral pathogens
389
Bacteria may be used to make nano sized material for?
Nanotechnology machines
390
Cells from plants w/ desirable characteristics can be cloned to produce many identical cells. These cells can then be used to?
Produce whole plants from which seeds can be harvested
391
Plant cells can be modified by using the Ti plasmid vector. The tumor-producing T genes are replaced w/ desired genes, and the recombinant DNA is inserted into Agrobacterium. The bacterium naturally______its plant hosts.
Transforms
392
Antisense DNA can prevent?
Expression of unwanted proteins
393
Strict safety standards are used to avoid the?
Accidental release of genetically modified microorganisms
394
Some microbes used in rDNA cloning have been altered so that?
They cannot survive outside the lab
395
Microorganisms intended for use in the environment may be modified to?
Contain suicide genes so that the organisms do not persist in the environment
396
Genetically modified crops must be safe for?
Consumption and for release in the environment.
397
Genetic analysis (SSU rRNA) lead to the division of prokaryotes into two domains.
Bacteria and Archaea
398
Prokaryotes, Domain Bacteria (gram negative) w/ a peptidoglycan cell wall and bacteria rRNA signature.
Nonproteobacteria and Proteobacteria
399
Prokaryotes, Domain Bacteria (gram positive) w/ a peptidoglycan cell wall and bacteria rRNA signature.
Low G+C Firmicutes and High G+C Actinobacteria
400
Prokaryotes, Pseudomurein cell wall and Archaea rRNA signature.
Domain Archaea
401
Phylum Proteobacteria
Constitutes the majority of known medically, industrially, and agriculturally significant bacteria
* Gram Negative
* Most metabolically and morphologically diverse group
* Divided into 5 true classes
* Includes Family Enterobacteriaceae, agroup of medically important enteric pathogens: E. coli, Salmonella, Shigella, and Yersinia
* Endosymbiotictheory and origin of mitochondria
402
Nonproteobacteria: Other Gram Negative Phyla, Phylum Chlamydiae
Extremely small, lack peptidoglycan. All obligately intracellular parasites with poor metabolic capacities
Can only be cultivated in vivo
Ex: Chlamydia trachomatis causes chlamydia
403
Nonproteobacteria: Other Gram Negative Phyla, Phylum Spirochaetes
Helical heterotrophs, Axial filaments for motility.
Some are pathogens:
•Borreliaburgdorfericauses Lyme disease
•Treponemapalidumcauses syphilis
404
Nonproteobacteria: Other Gram Negative Phyla, Phylum Cyanobacteria,
Oxygenic photosynthesis, “Oxygen revolution”
Plant chloroplasts likely evolved from cyanobacteria by the process of endosymbiosis
Many also reduce nitrogen to NH3via nitrogen fixation in heterocysts
405
Anoxygenicphotosynthesis
Phylum Chlorobi: green sulfur bacteria
Phylum Chloroflexi: green bacteria
406
Clostridium (Low G+C Gram Positive Bacteria)
Obligate anaerobic rods; endospore producers
Disease ex. Clostridium botulinum-botulism
407
Bacillus (Low G+C Gram Positive Bacteria)
Facultative anaerobic rods; endospore producers; many produce antibiotics
Disease ex. Bacillus anthracis–anthrax
408
Mycoplasma (Low G+C Gram Positive Bacteria)
Facultative or obligate anaerobes; highly pleomorphic;lack cell walls
Disease ex. Mycoplasma pneumoniae-walking pneumonia
409
Streptococcus (Low G+C Gram Positive Bacteria)
Cocci in chains; aerotolerantanaerobes
Disease Ex. Streptococcus pyogenes-strep throat
410
Staphylococcus (Low G+C Gram Positive Bacteria)
Cocci in clusters; facultative anaerobes; inhabit skin and mucous membranes
Disease ex. Staphylococcus aureus –skin infections and bacteremia
411
Phylum Actinobacteria(High G+C Gram Positive Bacteria)
Actinomycetesare soil-dwelling bacteria that often form branching filaments resembling fungi
412
Phylum Actinobacteria(High G+C Gram Positive Bacteria)
oStreptomycesare important decomposers and nutrient recyclers; 50% of all those isolated produce antibiotics
413
Phylum Actinobacteria(High G+C Gram Positive Bacteria)
Mycobacteriumhave cell walls containing mycolicacid (Ch4), exhibit acid fastness (Ch3) and slow growth
* M. tuberculosis causes TB
* M. lepraecauses leprosy
414
Phylum Actinobacteria(High G+C Gram Positive Bacteria)
Corynebacteriumare pleomorphic and have metachromatic granules in cytoplasm
•C. diptheriaecauses diphtheria
415
Domain Archaea
Not all are “extremophiles”
Many are mesophiles found in moderate habitats
No known human pathogens
Oceans contain many nitrifyingarchaeans
Methanogens: anaerobic; convert organic acids to methane gas; largest known
416
Domain Archaea
Extremophiles include:
Thermophiles: cell structures do not function properly below 45ºC
Halophiles:depend on greater than 9% NaCl to maintain integrity of cell wall; many contain pigments
Acidophiles: can thrive at very low pH
