Bacteria Growth, Nutrition, and Metabolism Flashcards
(115 cards)
1
Q
What are the characteristics of microbes?
A
Colorful, many shapes and sizes; ubiquitous: can be found anywhere.
2
Q
Growth often refers to _____________?
A
Increase in size.
3
Q
What is bacterial cell division?
A
Increase in number, also called bacterial reproduction.
4
Q
What is binary fission?
A
Dividing into 2 daughter cells from 1 to 2, 2 to 4, 4 to 8, etc.
5
Q
What components of the cell divide into daughter cells during binary fission?
A
The cell wall, membrane, and the chromosome.
6
Q
Cell division leads to what?
A
Arrangement of cells; daughter cells stick together and form different configurations or arrangements after binary fission.
7
Q
What is generation time?
A
Time required for a bacterium to give rise to two daughter cells under optimum conditions OR interval of time between two cell divisions; also referred to as population doubling time and varies for different organisms.
8
Q
What is the importance of generation time?
A
In the lab, we need to know how long it may take different groups of bacteria to grow and to be able to tell our clients when to expect results of bacteria growth and identification from a sample.
9
Q
What is the generation time for E. coli and other medically important coliforms?
A
20 mins.
10
Q
What is the generation time for Staph. aureus?
A
27-30 mins.
11
Q
What is the generation time for Mycobacterium tuberculosis?
A
20 hours.
12
Q
What is the generation time for Treponema pallidum?
A
33 hours.
13
Q
What is the generation time for Mycobacterium leprae?
A
20 days.
14
Q
How is bacterial growth seen on agar?
A
Seen as colonies.
15
Q
How is bacterial growth seen in liquids or broth?
A
Turbidity.
16
Q
How is bacterial growth seen on many inert surfaces?
A
Seen as thin spread: biofilm.
17
Q
What does each bacterial colony represent?
A
A clone of cells derived from a single parent cell.
18
Q
What is a culture?
A
Growing bacteria in the lab.
19
Q
What is culture media?
A
Type of growth nutrient used in the petri dish.
20
Q
What are colonies of bacteria?
A
“Dots” containing thousands or millions of each bacterial cells growing at a point on the agar.
21
Q
What are confluent colonies?
A
Many colonies touching one another.
22
Q
What are the 3 main types of media used for bacterial growth?
A
- Solid agar 2. Liquid broth 3. Inert surfaces.
23
Q
When a bacterium is added to a suitable liquid medium and incubated, its growth follows a _____________ course?
A
Definite.
24
Q
What are the 4 phases obtained in a growth curve?
A
- Lag phase - Log or exponential phase - Stationary phase - Decline phase.
25
What is the difference between a total count and a viable count?
Total count: dead and living cells; remains constant. Viable: only living cells; falls at the phase of decline.
26
Describe the lag phase of the growth curve.
- No immediate multiplication - Time to get used to environment - Nutrient assimilation - Preparation for cell division - No increase in population but increase in cell size - Max cell size towards the end of phase.
27
Describe the log/exponential phase of the growth curve.
- Cells start dividing and the number increases exponentially - Best for metabolic and structural studies by staining, antibiotic susceptibility, etc. - Smaller cell sizes - Stain uniformly.
28
Describe the stationary phase of the growth curve.
- Cell division stops - Equilibrium between dying cells and newly formed cells - Viable cell count remains constant and the curve plateaus - Irregular staining, sporulation, production of endotoxins and antibiotics.
29
Why does cell division stop in the stationary phase of the growth curve?
Nutrient depletion and toxic metabolite accumulation.
30
Describe the phase of decline of the growth curve.
- Population decreases due to the death of cells caused by autolytic enzymes - Involution with aging.
31
What are different methods for obtaining a total count measurement of bacteria?
- Direct count under microscope via counting chamber or via stained smears with known volume of culture - Coulter counter - Comparing relative numbers of smears with known number of other cells in a mixed culture - Opacity measurements i.e. absorptiometer or nephalometer - Separation via centrifugation or filtration and measuring their wet/dry weight - Chemical assay of cell components i.e. nitrogen.
32
Bacterial nutrition requirements are very similar to those of _____________?
Higher animals.
33
Why are bacterial nutrition requirements necessary?
To generate energy for growth, reproduction, and synthesis of cellular components.
34
What are the nutritional requirements of bacteria?
- Carbon - Nitrogen - Inorganic ions - Growth factors.
35
Describe the chemical composition of bacteria.
- 75-85% bound or free water - 15-25% dry matter: organic (proteins, lipids, polysachs, nucleic acids, and mucopeotides) and mineral substances (N, S, P, Ca, K, Na, MG, Mn).
36
What are the 2 types of bacteria nutrients?
- Macronutrients: needed in large quantities for metabolism and basic structure - Micronutrients: needed in small quantities for more specialized functions (enzyme and pigment structure and function).
37
Give examples of macronutrients and micronutrients.
Macro: C, H, O, N; Micro: Mn, Zn.
38
What are fastidious bacteria?
Microbes that require other complex nutrients/growth factors i.e. vitamins or AA's.
39
What are the most important pathogens?
Chemoheterotrophs.
40
What are the two energy sources for all organisms?
- Chemical: chemotroph - Light: phototroph.
41
What are the two carbon sources of chemotrophs?
Organic compounds: chemoheterotroph; CO2: chemoautotroph.
42
What are the two carbon sources of phototrophs?
Organic compounds: photoheterotrophs; CO2: photoautotrophs.
43
Describe chemoheterotrophs.
Energy and carbon both come from organic compounds, and the same compound can provide both.
44
What is the specific energy source of chemoheterotrophs?
Electrons from hydrogen atoms in organic compounds.
45
What are the two types of chemoheterotrophs?
- Saprophytes: live and feed on dead organic matter - Parasites: live and feed on living host.
46
What species are included in the chemoheterotroph group?
- Most bacteria - All protozoa, fungi, and animals - All microbes of medical importance.
47
What are growth factors/bacterial vitamins?
Certain organic compounds required by bacteria in minute quantities.
48
What are the two types of growth factors?
- Essential: growth does not occur in their absence i.e. X and V factors of H. influenza - Accessory: they enhance growth, but not absolutely necessary for it i.e. vitamin B complex.
49
List some factors that affect bacterial growth.
- Availability of nutrients and H2O - Temperature - Atmosphere (O2 and CO2) - H ion concentration (pH) - Moisture and drying - Osmotic effects - Radiation - Mechanical and sonic stress.
50
What are the different groupings of bacteria based on temperature?
- Psychrophiles: -10-20 degrees C - Psychrotrophs: 0-30 degrees C - Mesophiles: 10-48 degrees C - Thermophiles: 40-72 degrees C - Hyperthermophiles: 65-110 degrees C.
51
Most pathogens fall under which temperature group and why?
Mesophiles; most pathogens grow at about 37 degrees C which is the warm-blooded body temp, so, in order to cause disease they must thrive at this temperature.
52
What is the optimal growth temp for psychrophiles, mesophiles, and thermophiles?
Psychrophiles: 15 degrees C; Mesophiles: 35-40 degrees C; Thermophiles: 50-60 degrees C.
53
What are the characteristics of thermophiles?
- Bacteria and archaea that live in hot springs deep in the earth that can reach temperatures of 80 degrees C - Some produce enzymes that function at high temperatures - i.e. TAG polymerase used in PCR.
54
Why is optimal growth temperature of bacteria important?
- Need for appropriate sterilization temperatures - Food safety and preparation; some pathogens can live and multiply in the fridge.
55
The majority of bacteria grow best at what pH?
Neutral or slightly alkaline; near most normal body fluids: 7-7.4.
56
What are the 3 bacterial classifications based on pH?
Neutrophiles: grow best at pH 6-8; Acidophiles: grow best at low pH (1-5); Alkalophiles: grow best at high pH (9-11).
57
Give an example of a neutrophile, acidophile, and alkalophile.
Neutrophile: Mycobacterium tuberculosis; Acidophile: Lactobacilli; Alkalophile: V. cholerae.
58
What is freeze drying?
A method of preservation of organisms by keeping them in a dormant or inactive condition thus prolonging their life.
59
What is the essential ingredient of bacterial protoplasm?
Water.
60
Describe the effect of drying on microbes.
Highly variable - T. pallidum: highly sensitive - Staphylococci spp: stand for months - Spores: resistant to desiccation and can't survive for decades.
61
Most bacteria require what kind of osmotic environment for optimal growth?
Isotonic or hypotonic.
62
What is an osmotolerant organism?
An organism that can grow at a relatively high salt concentration (up to 10%)
63
What is a halophile?
Bacteria that require a relatively high salt concentration for growth; some archaea (halophilic vibrios) that require NaCl concentration of 20% or higher
64
The effect that salt has on non-halophilic organisms provides the basis for what?
Preserving meats and other food products in brine thus inhibiting food spoilage organisms
65
What are the two types of uptake of nutrients by bacteria?
- Passive transport (simple diffusion or facilitated diffusion)
- Active transport
66
What is passive transport?
Does not require energy; substances exist in a gradient and move from areas of higher concentration to areas of lower concentration
67
What is the difference between simple diffusion and facilitated diffusion?
Neither require energy but facilitated diffusion requires a carrier
68
What is active transport?
Movement that requires energy and carrier proteins and is independent of the gradient
69
What happens to the transported molecule in the case of group translocation?
It is chemically altered
70
What is radiation?
Exposure to X-rays or gamma rays; can be lethal
71
What can happen to bacteria in the case of mechanical or sonic stress?
May be ruptured
72
Most pathogens fall into what classification according to air requirement?
Facultative anaerobe
73
What is an aerobe?
Organism whose growth requires the presence of air or free oxygen
74
What is an obligate aerobe?
Grows only in the presence of O2; i.e. vibrio
75
What is an anaerobe?
Grows only or best in the absence of free oxygen
76
What is an obligate anaerobe?
Cannot grow in the presence of oxygen; i.e. Bacteroides fragilis
77
What is a microaerophile?
Grows best in a low concentration of oxygen; i.e. campylobacter
78
What is a facultative aerobe/anaerobe?
Adjusts its metabolism depending on oxygen concentration in which it is growing; i.e. staphylococcus aureus
79
What is an aerotolerant anaerobe?
An organism that always grows in an anaerobic mode and ignores the presence of oxygen; i.e. Cl. welchii
80
What is a capnoeic microbe?
Requires 3-10% CO2 for growth; i.e. Neisseria
81
Given that oxygen is toxic to microbes, what does their survival depend on?
The organism's ability to produce detoxifying enzymes
82
Why is oxygen toxic?
It is readily converted to radicals (singlet oxygen, superoxide, hydrogen peroxide, hydroxyl radical)
83
What are the most important oxygen detoxifying enzymes?
Superoxide dismutase and catalase (peroxidase)
84
Differences in a cell's content of detoxifying enzymes results in differences in what?
Their ability to grow in the presence of oxygen
85
Describe how oxygen is reduced and detoxified by aerobes.
- O2 is reduced to H2O2 by enzymes and to O2- by ferrous ion
- O2- is removed by superoxide dismutase
- H2O2 is removed by catalase
86
What are the two components of metabolism?
Catabolism and anabolism
87
What is anabolism?
- Biosynthesis (assimilation)
- Building of complex molecules from simple ones
- Requires energy in the form of ATP
88
What is catabolism?
- Degradation (dissimilation)
- Breaking down complex molecules into simple ones
- Generates ATP
89
What are the biochemical mechanisms utilized to generate energy?
- Aerobic respiration
- Anaerobic respiration
- Fermentation
90
The two components of metabolism occur _____________, with _____________ using ATP produced in _____________.
Simultaneously, anabolism, catabolism
91
What is the result of anabolism?
Uses ATP, nutrients, and micromolecules in the environment to build bacterial macromolecules like carbs, proteins, etc.
92
What are the pathways involved, final electron acceptor, and ATP yield of aerobic respiration?
Pathways: glycolysis, TCA, ET
Final e- acceptor: O2
ATP yield: 38
93
What are the pathways involved, final electron acceptor, and ATP yield of anaerobic respiration?
Pathways: glycolysis, TCA, ET
Final e- acceptor: NO3-, SO4-, CO3-
ATP yield: variable
94
What are the pathways involved, final electron acceptor, and ATP yield of fermentation?
Pathways: glycolysis
Final e- acceptor: organic molecules
ATP yield: 2
95
What is the energy currency of bacteria?
ATP
96
What are the components of ATP?
- Adenine: a nitrogenous base
- Ribose: a 5-carbon sugar
- 3 phosphate groups
97
How is energy released from ATP?
Removal of the terminal phosphate
98
What are the energy-generating patterns involved in the catabolism of glucose?
- Glycolysis
- Fermentation
- TCA cycle
- HMP pathway
99
Organisms catabolize what as the primary energy source for anabolic reactions?
Carbohydrates
100
Aerobic cellular respiration results in what?
The complete breakdown of glucose into CO2, water, and a lot of ATP
101
Anaerobic cellular respiration results in what?
Only the partial breakdown of glucose into pyruvic acid, organic waste products, and a little ATP
102
What is the first step in glucose metabolism?
Glycolysis (splitting of sugar) via carbohydrate catabolism
- Oxidation of glucose into 2 pyruvic acid molecules
- Degradation of CHO through a series of oxidative reactions (CHO's are excellent fuels as they are highly reduced structures that act as H- donors)
103
What are the steps in the aerobic respiration mechanism?
- Glycolysis produces pyruvate which enters the Krebs cycle
- Pyruvate metabolized into CO2 and H2O
- Krebs cycle generates much more ATP than the glycolytic cycle
104
Facultative bacteria grow faster in the presence of _____________?
Oxygen
105
What is the definition of aerobic cellular respiration?
Use of oxygen to break down food into usable energy
106
What are the 4 subpathways of cellular respiration?
1. Glycolysis
2. Synthesis of acetyl-CoA
3. Krebs cycle
4. Electron transport chain
107
What do the 4 subpathways of cellular respiration result in?
The complete breakdown of glucose into CO2, H2O, and ATP
108
Anaerobic respiration utilizes the same or different 3 coupled pathways as aerobic respiration?
Same
109
What are the final electron acceptors in anaerobic respiration and what organisms are they acceptors for?
- NO3-: Pseudomonas, Bacillus
- SO4-: Desulfovibrio
- CO3-: Methanogens
110
In what organisms would you see anaerobic respiration being used?
Facultative organisms as an alternative to aerobic respiration, or in obligate anaerobes
111
Why does anaerobic respiration produce a lower number of ATP than aerobic respiration?
Only part of the TCA occurs
112
What is fermentation?
Incomplete oxidation of glucose or other carbs in the absence of oxygen
113
What are used as terminal electron acceptors in fermentation?
Organic compounds
114
What are the final results of fermentation?
- A small amount of ATP
- Production of ethyl alcohol by yeasts acting on glucose
- Formation of acid, gas, and other products by the action of various bacteria on pyruvic acid
115
What is the best source of energy for most microorganisms?
Polysaccharides/glucose
