p.1
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What is the focus of Unit 2?
Metabolism of Prokaryotes.
p.1
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What are the two main types of microbial metabolism pathways?
Non-biosynthetic pathway and biosynthetic pathway.
p.1
Quantification of Bacterial Growth
What does the growth curve of bacteria represent?
The quantification of bacterial growth over time.
p.1
Adaptation Mechanisms of Microbes
What are halophiles?
Microbes that thrive in high salt concentrations.
p.1
Adaptation Mechanisms of Microbes
What are alkalophiles?
Microbes that prefer alkaline environments.
p.1
Adaptation Mechanisms of Microbes
What are psychrophiles?
Microbes that grow best at low temperatures.
p.1
Adaptation Mechanisms of Microbes
What are piezophiles?
Microbes that thrive under high pressure.
p.1
Adaptation Mechanisms of Microbes
What are xerophiles?
Microbes that can survive in very dry environments.
p.1
Bacterial Recombination: Transformation, Transduction, Conjugation
What are the three main types of bacterial recombination?
Transformation, transduction, and conjugation.
p.2
Bacterial Growth Curve and Kinetics
How is growth defined in microbiology?
As an increase in the number of cells.
p.34
Nutritional Requirements of Bacteria
How are nutrients utilized by bacteria?
In biosynthesis and energy production.
p.4
Phases of Bacterial Cell Cycle
What is FtsZ?
The major cytoskeletal protein in the bacterial cytokinesis machine.
p.33
Energy Utilization in Bacteria
What is the most commonly used practical form of energy in living organisms?
Adenosine 5'-triphosphate (ATP).
p.27
Quantification of Bacterial Growth
What are viable counting methods used for?
To determine the number of viable microbes in a sample.
p.51
Transport Mechanisms for Nutrient Uptake
What happens to the membrane carrier after binding an external molecule?
It changes conformation and releases the molecule inside the cell.
p.27
Quantification of Bacterial Growth
How are the results of viable counting often expressed?
In terms of colony forming units (CFU).
p.29
Quantification of Bacterial Growth
Why might plate counts be ineffective for measuring microbial populations?
If the microbe cannot be cultured on solid media or if large colonies overgrow the plate.
p.51
Transport Mechanisms for Nutrient Uptake
What is the state of the membrane carrier after releasing the molecule?
It returns to the outward oriented position, ready to bind another solute molecule.
p.41
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What are the three main aspects of microbial metabolism?
Utilization of energy, nutrient uptake, and biosynthesis of important molecules.
p.34
Nutritional Requirements of Bacteria
What is the role of nutrients in bacteria?
They provide nourishment essential for maintenance of life and growth.
p.25
Quantification of Bacterial Growth
What is a Coulter counter used for?
To directly count microorganisms.
p.46
Transport Mechanisms for Nutrient Uptake
What does the cytoplasmic membrane allow regarding small molecules?
It allows the passive passage of certain small molecules and actively concentrates others within the cell.
p.27
Quantification of Bacterial Growth
What do viable counting methods count?
Only those cells able to reproduce when cultured.
p.27
Quantification of Bacterial Growth
What are the two commonly used procedures for viable counting?
Spread plate and pour plate techniques.
p.46
Transport Mechanisms for Nutrient Uptake
Why can't nutrient molecules frequently cross plasma membranes through passive diffusion?
Because they must be transported by one of three major mechanisms involving membrane carrier proteins.
p.45
Nutritional Requirements of Bacteria
What is the primary focus of nutritional uptake in bacteria?
The process by which bacteria absorb nutrients from their environment.
p.4
Phases of Bacterial Cell Cycle
What is the function of the Z ring?
It constricts to initiate division of the cell.
p.29
Quantification of Bacterial Growth
What is the Most Probable Number (MPN) test used for?
To estimate microbial population size when plate counts are not applicable.
p.48
Transport Mechanisms for Nutrient Uptake
What is simple diffusion?
A process where a substance passes through a membrane without the aid of an intermediary, such as an integral membrane protein.
p.41
Energy Utilization in Bacteria
In what form is energy stored by microorganisms?
In the form of high-energy transfer compounds (ATP).
p.33
Energy Utilization in Bacteria
How do cells utilize ATP?
Cells 'earn' ATP through certain processes and 'spend' it in carrying out other processes.
p.45
Nutritional Requirements of Bacteria
What are the main types of nutrients that bacteria require?
Carbon, nitrogen, sulfur, phosphorus, and trace elements.
p.60
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What is an example of polymer synthesis occurring outside the membrane?
Synthesis of cell wall peptidoglycan.
p.59
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What do microbes do when only a few amino acids are present in the medium?
They convert other amino acids into those that are missing.
p.27
Quantification of Bacterial Growth
What is the purpose of serial dilution in viable counting?
To prepare samples for pour plate and spread plate techniques.
p.48
Transport Mechanisms for Nutrient Uptake
How do small noncharged or lipid-soluble molecules enter or leave bacterial cells?
By passing between the phospholipids, moving from areas of high concentration to areas of low concentration.
p.41
Energy Utilization in Bacteria
What is another form of energy available to microorganisms besides ATP?
Proton motive force (electrochemical proton gradient).
p.33
Energy Utilization in Bacteria
What is ATP often referred to as?
The cell's energy currency.
p.3
Phases of Bacterial Cell Cycle
What is the bacterial cell cycle?
The complete sequence of events from the formation of a new cell through the next division.
p.28
Quantification of Bacterial Growth
What technique is used to determine the number of bacteria in aquatic samples?
Membrane filter technique.
p.45
Transport Mechanisms for Nutrient Uptake
How do bacteria typically acquire nutrients?
Through various transport mechanisms such as passive diffusion, facilitated diffusion, and active transport.
p.25
Quantification of Bacterial Growth
How does a Coulter counter measure microbial cells?
By forcing a microbial suspension through a small hole and measuring electrical resistance.
p.46
Transport Mechanisms for Nutrient Uptake
What role do membrane carrier proteins play in bacterial nutrient uptake?
They facilitate the transport of nutrients that cannot cross the plasma membrane by passive diffusion.
p.4
Phases of Bacterial Cell Cycle
What is MreB?
A protein found in bacteria that is a homologue of actin.
p.10
Phases of Bacterial Cell Cycle
What happens to cells in batch culture after the stationary phase?
They enter the death phase.
p.60
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
Why is the synthesis of cell wall components significant?
Because polymerization takes place outside the cell membrane by enzymes on the membrane’s outer surface.
p.46
Transport Mechanisms for Nutrient Uptake
What are the processes by which ions or molecules cross the cytoplasmic membrane?
Various transport mechanisms involving membrane carrier proteins.
p.32
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What is required for microbial growth in terms of biochemical building blocks?
The polymerization of biochemical building blocks into proteins, nucleic acids, polysaccharides, and lipids.
p.49
Transport Mechanisms for Nutrient Uptake
What types of molecules can pass through the cytoplasmic membrane by passive diffusion?
Water and some lipid-soluble molecules.
p.3
Phases of Bacterial Cell Cycle
What is the first phase of the bacterial cell cycle?
A period of growth after the cell is born, similar to the G1 phase of the eukaryotic cell cycle.
p.47
Transport Mechanisms for Nutrient Uptake
What is facilitated transport?
A type of passive transport that uses carrier proteins to help move molecules across the membrane.
p.41
Energy Utilization in Bacteria
What are some biological purposes of the electrochemical proton gradient besides ATP synthesis?
Generating heat and rotation of bacterial flagella.
p.50
Transport Mechanisms for Nutrient Uptake
What happens to the carrier-solute complex during facilitated diffusion?
It moves between the outer and inner surfaces of the membrane, releasing one solute molecule on the inner surface.
p.32
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What additional requirement is placed on microbial growth by coenzymes?
Coenzymes participate in enzymatic catalysis.
p.23
Quantification of Bacterial Growth
What is the structure of a counting chamber?
It consists of specially designed slides and coverslips that create a chamber of known depth.
p.6
Bacterial Growth Curve and Kinetics
What happens to nutrient concentrations during batch culture incubation?
Nutrient concentrations decline as they are consumed.
p.53
Transport Mechanisms for Nutrient Uptake
Where does the sugar combine with enzyme II?
At the outer membrane surface.
p.47
Transport Mechanisms for Nutrient Uptake
What is the role of H+ ions in nutrient uptake?
They create a proton motive force that drives the transport of nutrients.
p.7
Phases of Bacterial Cell Cycle
What occurs after the lag phase?
Cells begin to replicate their DNA, increase in mass, and divide.
p.11
Adaptation Mechanisms of Microbes
What happens to the bacterial population during the long-term stationary phase?
It continually evolves, with actively reproducing cells best able to use released nutrients and tolerate toxins.
p.7
Phases of Bacterial Cell Cycle
What is the result of the activities during the lag phase?
The number of cells in the population begins to increase.
p.11
Bacterial Recombination: Transformation, Transduction, Conjugation
What is marked by successive waves of genetically distinct variants?
The dynamic process during the long-term stationary phase.
p.52
Transport Mechanisms for Nutrient Uptake
What is required for sugar uptake and phosphorylation in the phosphotransferase system?
Participation of several soluble and membrane-bound enzymes.
p.44
Energy Utilization in Bacteria
What is still unknown regarding the flagellar motor?
The molecular events that cause the conversion of proton motive force.
p.24
Quantification of Bacterial Growth
What additional characteristics can be analyzed using flow cytometry?
Size, internal complexity, and other characteristics of cells.
p.30
Quantification of Bacterial Growth
Why is measuring dry weight especially useful?
It is particularly useful for measuring the growth of filamentous fungi.
p.30
Quantification of Bacterial Growth
What is a limitation of the dry weight measurement technique?
It is time-consuming and not very sensitive.
p.48
Transport Mechanisms for Nutrient Uptake
What direction do molecules move during simple diffusion?
They move down their concentration gradient, from high to low concentration.
p.28
Quantification of Bacterial Growth
What type of membrane filter is used in the membrane filter technique?
Black polycarbonate membrane filter.
p.25
Quantification of Bacterial Growth
What happens to electrical resistance when a microbial cell passes through the hole in a Coulter counter?
Electrical resistance increases, causing conductivity to drop.
p.41
Energy Utilization in Bacteria
How does the electrochemical proton gradient contribute to microbial metabolism?
It results in ATP synthesis and can be used for other biological purposes.
p.25
Quantification of Bacterial Growth
What is the principle behind counting cells in a Coulter counter?
Each time a microbial cell passes through the hole, it is counted based on the change in electrical resistance.
p.53
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What activates the heat stable carrier protein HPr?
Transfer of a phosphate group from phosphoenol pyruvate (PEP).
p.55
Transport Mechanisms for Nutrient Uptake
What is the first step in the process of active transport?
Binding of a solute to a receptor site on a membrane-bound carrier protein.
p.26
Quantification of Bacterial Growth
What is a limitation of traditional counting methods for microbes?
They do not differentiate between live and dead cells.
p.53
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What are the roles of Enzyme I and HPr in the process?
They are soluble proteins and non-specific components.
p.3
Phases of Bacterial Cell Cycle
What is the third phase of the bacterial cell cycle?
Cytokinesis, during which a septum and daughter cells are formed.
p.7
Phases of Bacterial Cell Cycle
What must be synthesized before growth can begin in the lag phase?
New components such as ATP, cofactors, and ribosomes.
p.49
Transport Mechanisms for Nutrient Uptake
Does passive diffusion involve specific interactions between substances in the membrane and solute molecules?
No, there is no specific interaction in passive diffusion.
p.43
Energy Utilization in Bacteria
What is flagellin and what is its enzymatic activity?
Flagellin is a component of bacterial flagella and has no detectable ATPase activity.
p.42
Energy Utilization in Bacteria
How does ATP contribute to the activity of locomotor organelles in bacteria?
It powers the movement of flagella.
p.23
Quantification of Bacterial Growth
What is a disadvantage of using counting chambers?
To determine population size accurately, the microbial population must be relatively large and evenly dispersed.
p.37
Nutritional Requirements of Bacteria
From where do organotrophs extract electrons?
From reduced organic compounds.
p.47
Transport Mechanisms for Nutrient Uptake
What is the main function of the PTS system?
To phosphorylate and transport sugars into the cell.
p.35
Nutritional Requirements of Bacteria
How does Calcium (Ca2+) contribute to bacterial spores?
It contributes to heat resistance and many other functions.
p.11
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What does VBNC stand for?
Viable but non-culturable state.
p.19
Continuous Culture Systems: Chemostats and Turbidostats
How does the limiting nutrient affect growth rate in a chemostat?
Growth rate is determined by the rate at which sterile medium is fed into the growth chamber.
p.30
Quantification of Bacterial Growth
Why might it be necessary to centrifuge several hundred milliliters of culture?
Because bacteria weigh so little, a sufficient quantity is needed for measurement.
p.18
Continuous Culture Systems: Chemostats and Turbidostats
What type of growth do continuous culture systems maintain?
Exponential growth at a known rate and constant biomass concentration.
p.50
Transport Mechanisms for Nutrient Uptake
In facilitated diffusion, where does the solute molecule flow from and to?
From higher to lower concentration.
p.34
Nutritional Requirements of Bacteria
Why are nutrients essential for microbial growth?
They are required for building proteins, structural membranes, and driving biochemical processes.
p.2
Bacterial Growth Curve and Kinetics
What is necessary for a species to be maintained in microbiology?
Continued growth of its population.
p.51
Transport Mechanisms for Nutrient Uptake
What is the driving force for molecules to enter the cell during facilitated diffusion?
The concentration gradient, where the concentration is greater outside the cell.
p.2
Bacterial Growth Curve and Kinetics
What happens to macromolecules in the cytoplasm of a bacterial cell?
They assemble into major cell structures.
p.6
Bacterial Growth Curve and Kinetics
What is often studied to analyze population growth in microbes?
The growth of microbes in liquid (broth) culture.
p.32
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
Where must the building blocks for microbial growth come from?
They must come preformed in the growth medium or be synthesized by the growing cells.
p.49
Transport Mechanisms for Nutrient Uptake
What governs the rate of inward flow of solute molecules during passive diffusion?
The difference in concentration of the molecule across the membrane.
p.3
Phases of Bacterial Cell Cycle
What occurs during the second phase of the bacterial cell cycle?
Chromosome replication and partitioning, corresponding to the S and mitosis events of the M phase in eukaryotic cells.
p.7
Phases of Bacterial Cell Cycle
Why might cells be depleted during the lag phase?
Cells may be old and depleted of ATP, essential cofactors, and ribosomes.
p.2
Bacterial Growth Curve and Kinetics
What occurs when one bacterial cell separates to form two cells?
One generation has occurred.
p.37
Nutritional Requirements of Bacteria
How do chemotrophs obtain their energy?
From the oxidation of chemical compounds (either organic or inorganic).
p.43
Energy Utilization in Bacteria
What is the role of bacterial flagella filaments in energy utilization?
They have no machinery for interconverting chemical and mechanical energy.
p.23
Quantification of Bacterial Growth
How does the etched grid in the counting chamber assist in counting?
It facilitates counting the cells.
p.37
Nutritional Requirements of Bacteria
What are the two sources of electrons for microorganisms?
Reduced inorganic substances (lithotrophs) and reduced organic compounds (organotrophs).
p.31
Quantification of Bacterial Growth
What principle does spectrophotometry rely on?
Microbial cells scatter light.
p.8
Bacterial Growth Curve and Kinetics
Why are exponential phase cultures used in studies?
Because the population is most uniform in terms of chemical and physiological properties.
p.31
Quantification of Bacterial Growth
What happens to light transmission as cell concentration increases?
Less light is transmitted through the medium due to greater turbidity.
p.8
Bacterial Growth Curve and Kinetics
What factors influence the growth rate during the exponential phase?
Nutrient availability and environmental conditions.
p.56
Transport Mechanisms for Nutrient Uptake
What happens to the solute after the conformational change in the carrier molecule?
The solute is released into the cell interior.
p.30
Quantification of Bacterial Growth
What is one approach to measuring microbial cell mass?
Determination of microbial dry weight.
p.8
Bacterial Growth Curve and Kinetics
What happens to the growth rate as nutrient concentration increases?
The growth rate increases but eventually saturates, similar to enzyme kinetics.
p.39
Nutritional Requirements of Bacteria
What are vitamins in the context of growth factors?
Small organic molecules that are part of enzyme cofactors and needed in very small amounts.
p.13
Quantification of Bacterial Growth
What is the relationship between log N, log N₀, and n?
n = (log N - log N₀) / log 2.
p.13
Quantification of Bacterial Growth
What does the equation 0.301 = 3.3 (log N - log N₀) represent?
It relates the difference in logarithms of N and N₀ to a constant factor.
p.19
Continuous Culture Systems: Chemostats and Turbidostats
How is the rate of nutrient exchange in a chemostat expressed?
As the dilution rate (D).
p.12
Bacterial Growth Curve and Kinetics
How can the increase in cell number in an exponentially growing bacterial culture be expressed mathematically?
Using a geometric progression based on the number 2.
p.4
Phases of Bacterial Cell Cycle
What role does MreB play in bacteria?
It controls the width of rod-shaped bacteria.
p.55
Transport Mechanisms for Nutrient Uptake
What is active transport?
The transport of solute molecules to higher concentrations or against a concentration gradient using metabolic energy.
p.29
Quantification of Bacterial Growth
What alternative method is used when plate counts are not suitable?
Most Probable Number (MPN) determination.
p.22
Quantification of Bacterial Growth
Is there a single best technique for measuring microbial population size?
No, the most appropriate approach depends on the experimental situation.
p.42
Energy Utilization in Bacteria
How is much of the energy from ATP utilized in bacterial cells?
In the biosynthesis of new cell components.
p.16
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
How is the yield coefficient related to biomass production?
It relates to the quantity of biomass produced per gram of substrate utilized.
p.42
Energy Utilization in Bacteria
What are energy-storage inclusion granules mentioned?
Glycogen and poly-β-hydroxybutyrate.
p.54
Transport Mechanisms for Nutrient Uptake
What is released by Enzyme II after the transport process?
Sugar phosphate is released and enters the cell.
p.5
Bacterial Recombination: Transformation, Transduction, Conjugation
What is the function of crescentin in comma-shaped cells?
It localizes to one side of the cell and slows the insertion of new peptidoglycan units.
p.26
Quantification of Bacterial Growth
What newer methods help improve direct counting of microbes?
Fluorescent dyes that differentiate between live and dead cells.
p.16
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What does a higher yield coefficient indicate?
A greater percentage of the original substrate converted into microbial biomass.
p.5
Phases of Bacterial Cell Cycle
What does the asymmetric cell wall growth in Vibrio lead to?
The inner curvature that characterizes the comma shape.
p.32
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What is necessary for the maintenance of transmembrane gradients during microbial growth?
A source of metabolic energy.
p.23
Quantification of Bacterial Growth
How can the number of microorganisms in a sample be calculated?
From the chamber’s volume and any dilutions made of the sample before counting.
p.47
Transport Mechanisms for Nutrient Uptake
What is group translocation?
A process that alters the molecule being transported, often involving phosphorylation.
p.56
Transport Mechanisms for Nutrient Uptake
What change occurs in the carrier molecule during solute transport?
A conformational change that decreases its affinity for the solute.
p.13
Quantification of Bacterial Growth
How can the equation N = N₀ * 2^n be expressed in terms of n?
n = (log N - log N₀) / log 2.
p.52
Transport Mechanisms for Nutrient Uptake
What do the proteins in the phosphotransferase system catalyze?
The transfer of the phosphoryl group of phosphoenolpyruvate to the sugar molecule.
p.35
Nutritional Requirements of Bacteria
What is the role of Iron (Fe2+ and Fe3+) in microbial metabolism?
It is part of cytochromes and acts as a cofactor for enzymes and electron-carrying proteins.
p.39
Nutritional Requirements of Bacteria
How much do vitamins contribute to bacterial growth?
They are needed in only very small amounts to sustain growth.
p.11
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What does CASP refer to?
Constant activity stationary phase.
p.30
Quantification of Bacterial Growth
How can cell mass be estimated aside from dry weight?
By measuring the concentration of some cellular substance, like total protein or nitrogen.
p.18
Continuous Culture Systems: Chemostats and Turbidostats
What is a continuous culture system?
A system that maintains constant environmental conditions through continual supply of nutrients and removal of wastes.
p.29
Quantification of Bacterial Growth
What is a limitation of using plate counts for microbial enumeration?
They can be inaccurate if colonies overgrow the surface of the plate.
p.41
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What is the role of energy in microbial metabolism?
To drive many endergonic reactions required for the cell.
p.7
Phases of Bacterial Cell Cycle
What is the lag phase in microbial growth?
A period when no immediate increase in cell number occurs after microorganisms are introduced into fresh culture medium.
p.48
Transport Mechanisms for Nutrient Uptake
Which substances typically enter and leave cells by simple diffusion?
Oxygen, carbon dioxide, and most lipids.
p.55
Transport Mechanisms for Nutrient Uptake
What types of solutes are taken up by cells through active transport?
Sugars, amino acids, peptides, nucleosides, and ions.
p.7
Phases of Bacterial Cell Cycle
Is the lag phase a time of inactivity for microorganisms?
No, cells are actively synthesizing new components during this phase.
p.22
Quantification of Bacterial Growth
What factors are noted when examining techniques for determining population size?
Advantages and disadvantages of each technique.
p.52
Transport Mechanisms for Nutrient Uptake
What is group translocation?
A process where a solute is altered chemically during transport.
p.49
Transport Mechanisms for Nutrient Uptake
What happens to the concentration gradient over time during passive diffusion?
It diminishes until equilibrium is reached.
p.50
Transport Mechanisms for Nutrient Uptake
Can the carrier molecule in facilitated diffusion bind to new solute molecules?
Yes, it returns to bind a new one on the outer surface.
p.32
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What do biosynthetic polymerization reactions require for energy?
The transfer of anhydride bonds from adenosine triphosphate (ATP).
p.50
Transport Mechanisms for Nutrient Uptake
Give an example of facilitated diffusion.
The entry of glycerol into bacterial cells.
p.7
Phases of Bacterial Cell Cycle
What happens if the new culture medium is different from the previous one?
New enzymes are needed to utilize different nutrients.
p.37
Nutritional Requirements of Bacteria
What do lithotrophs use as their electron source?
Reduced inorganic substances.
p.24
Quantification of Bacterial Growth
What is flow cytometry used for?
To directly count microbes and gain detailed information about them.
p.58
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What types of enzymes are involved in liberating amino acids from proteins?
Intracellular and extracellular proteolytic enzymes.
p.52
Transport Mechanisms for Nutrient Uptake
What form do sugars accumulate in the cell during group translocation?
Phosphoenol pyruvate form.
p.31
Quantification of Bacterial Growth
What is the term for the extent of light scattering measured by a spectrophotometer?
Absorbance (optical density).
p.44
Energy Utilization in Bacteria
What drives the flagellar motor's rotation?
The inward flux of protons.
p.13
Quantification of Bacterial Growth
What is the logarithmic transformation of the equation N = N₀ * 2^n?
log N = log N₀ + n log 2.
p.31
Quantification of Bacterial Growth
What should be done if the absorbance sample exceeds 0.5?
The sample must be diluted before measuring absorbance.
p.19
Continuous Culture Systems: Chemostats and Turbidostats
What is a key characteristic of the culture medium in a chemostat?
It has a limited quantity of an essential nutrient.
p.8
Bacterial Growth Curve and Kinetics
What occurs at sufficiently high nutrient levels?
Transport systems become saturated, and the growth rate does not increase further with more nutrients.
p.19
Continuous Culture Systems: Chemostats and Turbidostats
What does the final cell density in a chemostat depend on?
The concentration of the limiting nutrient.
p.54
Transport Mechanisms for Nutrient Uptake
What is the function of Enzyme II?
It is specific for a particular sugar and facilitates its transport into the cell.
p.37
Nutritional Requirements of Bacteria
How are microorganisms classified based on their source of carbon?
As either heterotrophs or autotrophs.
p.16
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What is the yield coefficient (Y) based on?
The quantity of rate-limiting nutrient, typically the substrate converted into microbial product.
p.23
Quantification of Bacterial Growth
What is the primary method for direct measurement of cell numbers?
Using a counting chamber, such as the Petroff-Hausser counting chamber.
p.37
Nutritional Requirements of Bacteria
What are the two sources of energy available to organisms?
Light energy and energy from oxidizing organic or inorganic molecules.
p.43
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What is primarily maintained through reactions leading to biosynthesis of macromolecules in bacteria?
The physical and chemical integrity of the cell.
p.2
Bacterial Growth Curve and Kinetics
What major cell structures are formed from macromolecules?
Cell wall, cytoplasmic membrane, flagella, ribosomes, enzyme complexes.
p.36
Nutritional Requirements of Bacteria
What role do micronutrients play in microorganisms?
They are part of enzymes and cofactors, aiding in catalysis of reactions and maintenance of protein structure.
p.11
Phases of Bacterial Cell Cycle
What is the long-term stationary phase in microbial growth?
A period where the population size remains constant after exponential death.
p.6
Bacterial Growth Curve and Kinetics
How is population growth of microbes plotted in a batch culture?
As the logarithm of the number of viable cells versus incubation time.
p.56
Transport Mechanisms for Nutrient Uptake
How is the proton motive force utilized in the cell?
To pump solutes into the cell.
p.35
Nutritional Requirements of Bacteria
What are macronutrients?
Elements required by microorganisms in relatively large amounts.
p.43
Energy Utilization in Bacteria
How do bacterial flagella differ from cilia and flagella of eukaryotic microorganisms?
Bacterial flagella are much simpler and lack the machinery for energy conversion.
p.35
Nutritional Requirements of Bacteria
Which six elements are the primary components of carbohydrates, lipids, proteins, and nucleic acids?
Carbon (C), Oxygen (O), Hydrogen (H), Nitrogen (N), Sulfur (S), and Phosphorus (P).
p.47
Transport Mechanisms for Nutrient Uptake
What does PTS stand for in nutrient uptake?
Phosphotransferase system.
p.44
Energy Utilization in Bacteria
Where is the S ring mounted in the flagellar motor?
Rigidly on the cell wall.
p.31
Quantification of Bacterial Growth
How is absorbance related to cell concentration at levels below 0.5?
Absorbance is almost linearly related to cell concentration.
p.19
Continuous Culture Systems: Chemostats and Turbidostats
What is a chemostat?
A device where the rate of sterile medium input equals the rate of medium containing microorganisms output.
p.8
Bacterial Growth Curve and Kinetics
What reflects the rate of nutrient uptake by microbial transport proteins?
The shape of the growth curve during the exponential phase.
p.57
Transport Mechanisms for Nutrient Uptake
Which transport mechanism is characterized by specificity?
Facilitated diffusion, Active transport, and Group translocation.
p.57
Transport Mechanisms for Nutrient Uptake
Which transport mechanisms can move solutes against their gradient?
Active transport and Group translocation.
p.57
Transport Mechanisms for Nutrient Uptake
Which transport mechanism requires carrier proteins?
Facilitated diffusion, Active transport, and Group translocation.
p.59
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What must microorganisms do when the medium contains only inorganic sources of nitrogen?
Synthesize all the required amino acids from these nitrogen sources.
p.10
Phases of Bacterial Cell Cycle
How does the number of viable cells change during the death phase?
It declines exponentially.
p.45
Transport Mechanisms for Nutrient Uptake
What role do transport proteins play in bacterial nutritional uptake?
They facilitate the movement of nutrients across the bacterial cell membrane.
p.54
Transport Mechanisms for Nutrient Uptake
Where is Enzyme II located?
It is an integral component of the cytoplasmic membrane.
p.36
Nutritional Requirements of Bacteria
Which micronutrients are commonly needed by most cells?
Manganese, zinc, cobalt, molybdenum, nickel, and copper.
p.56
Energy Utilization in Bacteria
What drives protons out of the cell during electron transport?
Energy released during the flow of electrons through the ETC or the splitting of the phosphate group from ATP.
p.10
Phases of Bacterial Cell Cycle
What causes cells to enter the death phase?
Detrimental environmental changes such as nutrient deprivation and toxic waste buildup.
p.36
Nutritional Requirements of Bacteria
Do micronutrients usually limit microbial growth in nature?
No, they are ubiquitous and probably do not usually limit growth.
p.56
Energy Utilization in Bacteria
What does the movement of protons create across the cell membrane?
A difference in pH value and electric potential.
p.58
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What are amino acids considered in relation to proteins?
Building blocks of protein.
p.54
Transport Mechanisms for Nutrient Uptake
What is the reaction that occurs involving Enzyme II?
Sugar + phospho-HPr → sugar-phosphate + HPr.
p.26
Quantification of Bacterial Growth
What can fluorescent dyes help researchers determine in a microbial sample?
The number of live and dead microorganisms.
p.8
Bacterial Growth Curve and Kinetics
How does the growth rate behave during the exponential phase?
The growth rate is constant, with cells doubling in number at regular intervals.
p.20
Continuous Culture Systems: Chemostats and Turbidostats
What is a turbidostat?
The second type of continuous culture system that measures turbidity in the growth vessel.
p.56
Transport Mechanisms for Nutrient Uptake
What happens when protons reenter the cell?
The energy released drives the transport mechanism in the cell membrane.
p.20
Continuous Culture Systems: Chemostats and Turbidostats
How does a turbidostat maintain a predetermined turbidity?
By automatically regulating the flow rate of media through the vessel.
p.24
Quantification of Bacterial Growth
How does a flow cytometer create a stream of cells?
It creates a stream so narrow that one cell at a time passes through a beam of laser light.
p.8
Bacterial Growth Curve and Kinetics
How does the concentration of a limiting nutrient affect microbial growth?
Final net growth increases with the initial amount of the limiting nutrient present.
p.39
Nutritional Requirements of Bacteria
What is the role of purines and pyrimidines in bacterial growth?
They are needed for nucleic acid synthesis.
p.30
Quantification of Bacterial Growth
How are cells collected for dry weight measurement?
By centrifugation, followed by washing, drying in an oven, and weighing.
p.44
Energy Utilization in Bacteria
What constitutes the energy currency in flagellar rotation?
Proton movements, not ATP.
p.11
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What is SCDI in the context of microbial growth?
Stationary phase contact-dependent inhibition.
p.12
Bacterial Growth Curve and Kinetics
What does the expression N = N0 * 2^n represent?
The relationship between the initial number of cells (N0) and the final number of cells (N) after n generations.
p.22
Quantification of Bacterial Growth
What is examined to determine population size?
Commonly employed techniques.
p.42
Energy Utilization in Bacteria
What is ATP formed by in bacterial cells?
Energy producing reactions.
p.36
Nutritional Requirements of Bacteria
What are micronutrients?
Nutrients required by microorganisms in small amounts, also known as trace elements.
p.59
Energy Utilization in Bacteria
What is required for the interconversion and biosynthesis of chemical substances in microbes?
The expenditure of energy.
p.10
Phases of Bacterial Cell Cycle
What is the rate of cell death during the death phase?
Cells die at a constant rate.
p.45
Transport Mechanisms for Nutrient Uptake
What is the difference between passive and active transport in bacteria?
Passive transport does not require energy, while active transport requires energy to move substances against their concentration gradient.
p.51
Transport Mechanisms for Nutrient Uptake
Is energy required for facilitated diffusion?
No, there is no energy input required.
p.23
Quantification of Bacterial Growth
What are the advantages of using a counting chamber?
It is easy, inexpensive, and relatively quick, providing information about size and morphology of microorganisms.
p.43
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What macromolecules are continuously broken down and need replacement in bacterial cells?
Nucleic acids and proteins.
p.42
Energy Utilization in Bacteria
What other metabolic processes utilize ATP in bacterial cells?
Maintaining physical and chemical integrity, transport of solutes, and activity of locomotor organelles.
p.42
Energy Utilization in Bacteria
What role does ATP play in the transport of solutes across membranes?
It provides the energy required for the transport processes.
p.16
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
Why is the determination of yield coefficient important?
It decides how productive and cost-viable the medium used is.
p.31
Quantification of Bacterial Growth
How is light scattering related to biomass in a microbial population?
It is directly proportional to the biomass of cells present.
p.44
Energy Utilization in Bacteria
How is the rod of the flagellar motor connected?
It is fixed rigidly to the M ring, which rotates freely in the cytoplasmic membrane.
p.35
Nutritional Requirements of Bacteria
What role does Potassium (K+) play in microbial cells?
Required for activity by a number of enzymes, including those involved in protein synthesis.
p.39
Nutritional Requirements of Bacteria
Why are amino acids important for bacteria?
They are needed for protein synthesis.
p.20
Continuous Culture Systems: Chemostats and Turbidostats
How do turbidostats differ from chemostats?
The dilution rate in a turbidostat varies, while it remains constant in a chemostat.
p.35
Nutritional Requirements of Bacteria
What is the function of Magnesium (Mg2+) in microbial cells?
It acts as a cofactor for many enzymes, complexes with ATP, and stabilizes ribosomes and cell membranes.
p.31
Quantification of Bacterial Growth
What condition must be met for population size to be easily measured using turbidity?
The population must be high enough to give detectable turbidity.
p.19
Continuous Culture Systems: Chemostats and Turbidostats
What is the formula for calculating the dilution rate (D) in a chemostat?
D = f / V, where f is the flow rate and V is the vessel volume.
p.53
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What are the products formed in the reaction described?
Sugar phosphate and pyruvate.
p.50
Transport Mechanisms for Nutrient Uptake
What distinguishes facilitated diffusion from passive diffusion?
It involves a specific protein carrier molecule (porter or permease).
p.28
Quantification of Bacterial Growth
What is done to the bacteria after they are trapped on the membrane filter?
They are stained with nucleic acid fluorescent stains.
p.26
Quantification of Bacterial Growth
Why do traditional methods for counting microbes yield higher cell densities?
Because they do not distinguish dead cells from culturable cells.
p.54
Transport Mechanisms for Nutrient Uptake
What does Enzyme II combine with during the transport process?
It combines with the phosphate group carried by the activated HPr.
p.58
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What is the role of ATP in biosynthetic processes?
To convert one chemical substance into another and to synthesize complex substances from simpler ones.
p.16
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What does the equation x = Yx/s(S – Sr) represent?
It represents biomass concentration (x), yield coefficient (Yx/s), initial substrate concentration (S), and residual substrate concentration (Sr).
p.55
Transport Mechanisms for Nutrient Uptake
What occurs during the second step of active transport?
Translocation of the solute-carrier complex across the membrane.
p.52
Transport Mechanisms for Nutrient Uptake
What is an example of a system involved in group translocation?
Phosphoenol pyruvate dependent sugar-phosphotransferase system.
p.8
Bacterial Growth Curve and Kinetics
What occurs during the exponential phase of microbial growth?
Microorganisms grow and divide at the maximal rate possible given their genetic potential, medium nature, and environmental conditions.
p.55
Transport Mechanisms for Nutrient Uptake
What is the purpose of coupling translocation to an energy-yielding reaction in active transport?
To lower the affinity of the carrier protein for the solute at the inner membrane surface, allowing the release of solute to the cell interior.
p.53
Transport Mechanisms for Nutrient Uptake
What happens to the sugar after it combines with enzyme II?
It is transported to the inner membrane surface.
p.58
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What happens if amino acids are not freely available in the medium?
Microorganisms may have to liberate amino acids from proteins using proteolytic enzymes.
p.39
Nutritional Requirements of Bacteria
What are growth factors?
Organic compounds essential for cell components that cannot be synthesized by the organism.
p.6
Bacterial Growth Curve and Kinetics
What are the five distinct phases of the bacterial growth curve?
Lag Phase, Exponential Phase, Stationary Phase, Death Phase, Long-Term Stationary Phase.
p.39
Nutritional Requirements of Bacteria
What are the three major classes of growth factors?
Amino acids, Purines and Pyrimidines, and Vitamins.
p.11
Microbial Metabolism: Non-Biosynthetic and Biosynthetic Pathways
What does GASP stand for?
Growth Advantage in Stationary Phase.
p.24
Quantification of Bacterial Growth
How is the number of cells in a sample determined using flow cytometry?
By counting the number of light-scattering events.
p.20
Continuous Culture Systems: Chemostats and Turbidostats
What is the nutrient condition in a turbidostat?
All nutrients are in excess, meaning none are limiting.
p.24
Quantification of Bacterial Growth
What is often used to enhance the analysis of cells in flow cytometry?
Fluorescent dyes or fluorescently labeled antibodies.
p.24
Quantification of Bacterial Growth
What valuable information can flow cytometry provide?
Characteristics of the population of cells.
p.38
Nutritional Requirements of Bacteria
Which microbes are representative of Photoorganoheterotrophy?
Purple nonsulfur bacteria, green nonsulfur bacteria.
p.30
Quantification of Bacterial Growth
What can chlorophyll determinations measure?
Phototrophic protist and cyanobacterial populations.
p.38
Nutritional Requirements of Bacteria
What type of electron donor is used in Photolithoautotrophy?
Inorganic electron donor.
p.30
Quantification of Bacterial Growth
What does an increase in microbial population indicate?
Higher total protein levels.
p.38
Nutritional Requirements of Bacteria
Which bacteria are examples of Chemolithoheterotrophy?
Some sulfur-oxidizing bacteria (e.g., Beggiatoa).
p.9
Phases of Bacterial Cell Cycle
What factors influence the final population size in the stationary phase?
Nutrient availability, other factors, and the type of microorganism.
p.9
Phases of Bacterial Cell Cycle
What may cause the stationary phase to occur?
A balance between cell division and cell death, or ceasing to divide while remaining metabolically active.
p.38
Nutritional Requirements of Bacteria
What type of electron donor is used in Chemolithoautotrophy?
Inorganic electron donor.
p.18
Continuous Culture Systems: Chemostats and Turbidostats
How can continuous culture systems model interactions between microbial species?
By simulating environmental conditions resembling those in a freshwater lake.
p.18
Continuous Culture Systems: Chemostats and Turbidostats
Why are continuous culture systems important for microbial research?
They allow the study of microbial growth at very low nutrient levels, similar to natural environments.
p.12
Bacterial Growth Curve and Kinetics
What do the variables N, N0, and n stand for in the growth equation?
N is the final cell number, N0 is the initial cell number, and n is the number of generations.
p.12
Bacterial Growth Curve and Kinetics
How is the generation time (g) calculated in an exponentially growing population?
g = t/n, where t is the duration of exponential growth.
p.38
Nutritional Requirements of Bacteria
Which types of microbes are included in Chemoorganoheterotrophy?
Most nonphotosynthetic microbes, including most pathogens, fungi, many protists, and many archaea.
p.9
Phases of Bacterial Cell Cycle
What can lead to the cessation of population growth besides nutrient limitation?
Accumulation of toxic waste products.
p.9
Phases of Bacterial Cell Cycle
What happens to population growth in a closed system like a batch culture?
Population growth eventually ceases and the growth curve becomes horizontal.
p.18
Continuous Culture Systems: Chemostats and Turbidostats
What two major types of continuous culture systems are commonly used?
Chemostats and turbidostats.
p.18
Continuous Culture Systems: Chemostats and Turbidostats
In what areas are continuous culture systems essential?
Microbial ecology, food microbiology, and industrial microbiology.
p.12
Bacterial Growth Curve and Kinetics
What is the significance of knowing the initial and final cell numbers in a bacterial culture?
It allows for the calculation of the number of generations (n) and the generation time (g).
p.12
Bacterial Growth Curve and Kinetics
What does the variable t represent in the context of bacterial growth?
The duration of exponential growth expressed in days, hours, or minutes.
