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Microbes can grow under a wide range of ______ concentrations.
Microbes can grow under a wide range of ______ concentrations.
solute
The availability of water affects the growth of all ______.
The availability of water affects the growth of all ______.
cells
Higher ______ concentration leads to lower water activity.
Higher ______ concentration leads to lower water activity.
solute
A hypotonic solution has a ______ extracellular solute concentration.
A hypotonic solution has a ______ extracellular solute concentration.
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An isotonic solution has the same ______ concentration in and out.
An isotonic solution has the same ______ concentration in and out.
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A hypertonic solution has a ______ extracellular solute concentration.
A hypertonic solution has a ______ extracellular solute concentration.
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Molecular chaperones help to ______ damaged proteins.
Molecular chaperones help to ______ damaged proteins.
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Lipids in membranes are stabilized with ______ linkage instead of ester.
Lipids in membranes are stabilized with ______ linkage instead of ester.
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Enzymes ___________________ are catalase positive.
Enzymes ___________________ are catalase positive.
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Superoxide dismutase (SOD) breaks down ___________________ into oxygen and water.
Superoxide dismutase (SOD) breaks down ___________________ into oxygen and water.
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Microbes that grow in extremely high temperatures are called ___________________.
Microbes that grow in extremely high temperatures are called ___________________.
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The bacterium ___________________ is a source of Taq Polymerase.
The bacterium ___________________ is a source of Taq Polymerase.
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Microbes that grow in temperatures between 20-45°C are called ___________________.
Microbes that grow in temperatures between 20-45°C are called ___________________.
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High temperature disrupts membranes, denatures ___________________ and DNA.
High temperature disrupts membranes, denatures ___________________ and DNA.
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Microbes that grow in low temperatures are called ___________________.
Microbes that grow in low temperatures are called ___________________.
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Catalase breaks down ___________________ into water and oxygen.
Catalase breaks down ___________________ into water and oxygen.
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Halophile microorganisms require high ______ to grow
Halophile microorganisms require high ______ to grow
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Osmotolerant microorganisms can grow over a wide range of ______
Osmotolerant microorganisms can grow over a wide range of ______
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Xerophile microorganisms grow best at low ______
Xerophile microorganisms grow best at low ______
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Microbes survive in highly concentrated environments by using ______ solutes
Microbes survive in highly concentrated environments by using ______ solutes
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Examples of compatible solutes include potassium chloride, betaken, and some ______ acids
Examples of compatible solutes include potassium chloride, betaken, and some ______ acids
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Osmotolerant microorganisms, such as Staphylococcus, are ______ tolerant
Osmotolerant microorganisms, such as Staphylococcus, are ______ tolerant
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Cronobacter microorganisms thrive in ______ conditions
Cronobacter microorganisms thrive in ______ conditions
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Mannitol Salt Agar is used to select for ______-tolerant microorganisms
Mannitol Salt Agar is used to select for ______-tolerant microorganisms
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What type of transport does not require energy and relies on a gradient from higher to lower concentrations?
What type of transport does not require energy and relies on a gradient from higher to lower concentrations?
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What is the primary function of active transport in microbes?
What is the primary function of active transport in microbes?
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What is the name of the primary active transport mechanism that uses ATP to move substances across the cell membrane?
What is the name of the primary active transport mechanism that uses ATP to move substances across the cell membrane?
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What is the key difference between primary and secondary active transport?
What is the key difference between primary and secondary active transport?
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What type of transport uses membrane carrier proteins to facilitate the movement of molecules across the cell membrane?
What type of transport uses membrane carrier proteins to facilitate the movement of molecules across the cell membrane?
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What is the name of the process that involves the movement of molecules across the cell membrane without the use of energy?
What is the name of the process that involves the movement of molecules across the cell membrane without the use of energy?
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What is the term for the movement of molecules against their concentration gradient using energy from the proton gradient?
What is the term for the movement of molecules against their concentration gradient using energy from the proton gradient?
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What is the name of the process that involves the transport of molecules across the cell membrane coupled with a chemical reaction, such as group translocation?
What is the name of the process that involves the transport of molecules across the cell membrane coupled with a chemical reaction, such as group translocation?
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What is the main function of Uptake ABC transporters in bacterial cells?
What is the main function of Uptake ABC transporters in bacterial cells?
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What is the primary mechanism of Multidrug Efflux pumps in bacterial cells?
What is the primary mechanism of Multidrug Efflux pumps in bacterial cells?
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What is the energy source used in Secondary Active Transport?
What is the energy source used in Secondary Active Transport?
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What is the role of the phosphotransferase system in bacterial cells?
What is the role of the phosphotransferase system in bacterial cells?
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How do microbes acquire iron, a essential nutrient, from their environment?
How do microbes acquire iron, a essential nutrient, from their environment?
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What is the difference between catabolism and anabolism in cellular metabolism?
What is the difference between catabolism and anabolism in cellular metabolism?
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What is the primary function of siderophores in microbial cells?
What is the primary function of siderophores in microbial cells?
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What is the importance of enzymes in cellular metabolism?
What is the importance of enzymes in cellular metabolism?
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How does an enzyme lower activation energy to increase the rate of reaction?
How does an enzyme lower activation energy to increase the rate of reaction?
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In oxidation-reduction reactions, what is the direction of electron movement?
In oxidation-reduction reactions, what is the direction of electron movement?
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What is the significance of redox reactions in metabolism?
What is the significance of redox reactions in metabolism?
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What is the definition of oxidation in the context of redox reactions?
What is the definition of oxidation in the context of redox reactions?
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In redox reactions, what is the term for the substance that loses electrons?
In redox reactions, what is the term for the substance that loses electrons?
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Rhizobium is in ______ with plants
Rhizobium is in ______ with plants
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Azotobacter is ______ living in soil
Azotobacter is ______ living in soil
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Passive transport does not require ______ energy
Passive transport does not require ______ energy
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Facilitated diffusion is a type of ______ transport
Facilitated diffusion is a type of ______ transport
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ABC transporters are found in all ______ of life
ABC transporters are found in all ______ of life
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Food must enter the cell ______ membranes
Food must enter the cell ______ membranes
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Active transport moves nutrients ______ the concentration gradient
Active transport moves nutrients ______ the concentration gradient
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The more negative the ______ the better the donor.
The more negative the ______ the better the donor.
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Half reactions are written as: Acceptor + #e -> ______.
Half reactions are written as: Acceptor + #e -> ______.
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Couples with more negative ______ will donate e- to couples with more positive E0.
Couples with more negative ______ will donate e- to couples with more positive E0.
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The Electron Tower shows the ______ potential of various redox couples.
The Electron Tower shows the ______ potential of various redox couples.
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Freely diffusible electron carriers include ______ and NADP+.
Freely diffusible electron carriers include ______ and NADP+.
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Membrane-bound electron carriers include flavoproteins, cytochromes, and ______.
Membrane-bound electron carriers include flavoproteins, cytochromes, and ______.
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The reduced forms of freely diffusible electron carriers, such as NADH and ______, are the reducing power of the cell.
The reduced forms of freely diffusible electron carriers, such as NADH and ______, are the reducing power of the cell.
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Membrane-bound electron carriers are important components of ______ Transport Chains.
Membrane-bound electron carriers are important components of ______ Transport Chains.
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Metabolism involves ______ reactions and electron carriers.
Metabolism involves ______ reactions and electron carriers.
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In ______ reactions, electrons move from donor to acceptor.
In ______ reactions, electrons move from donor to acceptor.
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Oxidation is the removal of ______, while reduction is the addition of ______.
Oxidation is the removal of ______, while reduction is the addition of ______.
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The substance oxidized is the ______, and the substance reduced is the ______.
The substance oxidized is the ______, and the substance reduced is the ______.
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Oxidation-reduction reactions can result in ______ release, which can be used to form ATP.
Oxidation-reduction reactions can result in ______ release, which can be used to form ATP.
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Redox reactions often involve the transfer of ______ and ______ (H atom, example: NAD+/NADH).
Redox reactions often involve the transfer of ______ and ______ (H atom, example: NAD+/NADH).
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Study Notes
Enzymes and Microbial Growth
- Enzymes catalyze chemical reactions, with Catalase being an example of an enzyme that breaks down hydrogen peroxide (H2O2) into water and oxygen.
- Superoxide dismutase (SOD) is another enzyme that converts superoxide ions into hydrogen peroxide and oxygen.
Microbial Growth Temperature
- Microbes can grow under a wide range of temperatures, including:
- Hyperthermophiles: 85-113°C (e.g. Thermus aquaticus, source of Taq Polymerase)
- Thermophiles: 45-85°C (e.g. Thermus aquaticus)
- Mesophiles: 20-45°C (e.g. Escherichia coli)
- Psychrophiles: 0-20°C (e.g. Chlamydomonas)
Microbial Adaptation to High Temperature
- High temperatures can disrupt membranes, denature proteins and DNA, but thermophiles adapt by:
- Using solutes to maintain cellular structure and function
- Producing heat-shock proteins to stabilize cellular components
Solute Concentration and Water Activity
- Microbes can grow under a wide range of solute concentrations, which affects water activity (aw)
- Halophiles require high salt concentrations to grow
- Osmotolerant microbes grow over a wide range of aw (e.g. Staphylococcus, salt tolerant)
- Xerophiles grow best at low aw (e.g. Cronobacter, grows in dry conditions)
Microbial Survival in Concentrated Environments
- Microbes survive in highly concentrated environments by using compatible solutes (e.g. potassium chloride, betaine, some amino acids)
Microbial Nutrition
- Microbes require a supply of raw materials and nutrients to obtain energy and construct new cellular components
- Nutrients are substances used in biosynthesis and energy release, and are required for growth
- 95% of the microbial cell dry weight is made up of a few major elements
Microbial Response to Stress
- Microbes respond to stress by:
- Stabilizing proteins through increased hydrogen and covalent bonds, and molecular chaperones
- Stabilizing DNA by synthesizing proteins to coat it
- Stabilizing membranes by using lipids with ether linkages instead of ester linkages
Types of Microbes
- Rhizobium: in symbiosis with plants
- Azotobacter: free-living in soil
Acquiring Nutrients
- Rapid growth of microbes presents challenges in acquiring nutrients
- Food must enter cells at high rates, across membranes, in a selective fashion, and often against a concentration gradient
- Passive and active transport systems are used to acquire nutrients
Passive Transport
- No energy required
- Requires a gradient from high to low concentrations
- Facilitated diffusion: uses membrane carrier proteins
- Passive diffusion: only for small molecules and certain gases
Active Transport
- Energy-dependent
- Moves nutrients against a concentration gradient
- Uses ATP or proton motive force
- Two types: primary and secondary
Primary Active Transport
- ATP-binding cassette (ABC) transporters
- Found in all domains of life
- Can move substances in or out of cells
- Uptake ABC transporters: move nutrients in
- Export ABC transporters: move substances out, also known as multidrug efflux pumps
Secondary Active Transport
- Uses potential energy of ion gradients
- Example: Lac permease
- Electron transport generates a proton gradient, which can be used to do work
Active Transport: Group Translocation
- Example: phosphotransferase system in bacteria
- Nutrient is chemically altered
- Energy from phosphoenolpyruvate attaches to sugars
- Phosphoenolpyruvate is a key intermediate in glycolysis
Iron Uptake
- Problem: little free iron available, often in insoluble form (ferric iron, Fe3+)
- Solution: microbes release siderophores to acquire Fe
- Siderophore-Fe complex is then transported into cells, often using ABC transporters
Introduction to Metabolism
- Metabolism: all chemical reactions in a cell
- Catabolism: breakdown of complex molecules into smaller ones with release of energy for anabolism
- Anabolism: reactions that build cells
Metabolism Requirements
- Metabolism requires a flow of energy (capacity to do work) and the participation of enzymes
- Enzymes increase local concentrations of substrate and orient substrates properly for reactions to proceed
Metabolism Involves Oxidation-Reduction (Redox) Reactions and Electron Carriers
- Electrons move from donor to acceptor
- Utilize carriers
- Redox reactions can result in energy release, which can be used to form ATP
Oxidation-Reduction Reactions
- Oxidation: removal of electrons
- Reduction: addition of electrons
- Substance oxidized is donor, substance reduced is acceptor (pair = redox couple)
- Often involve not just the transfer of electrons but also an electron and proton (H atom)
Reduction Potential (E0)
- Measures the tendency of a donor to lose electrons
- More negative E0 indicates a better donor, while more positive E0 indicates a better acceptor
Half Reactions and Redox Couples
- Half reactions are written as: Acceptor + #e -> Donor
- A redox couple (or pair) consists of an acceptor and a donor
- Couples with more negative E0 will donate electrons to couples with more positive E0
The Electron Tower
- The electron tower shows the energy released when electrons move from a donor to an acceptor
- The greater the difference in E0, the more energy is released
Electron Carriers in Redox Reactions
- Electron carriers can be divided into two classes: freely diffusible and membrane-bound
- Freely diffusible carriers, such as NAD+ and NADP+, are found in the cytoplasm and provide reducing power to the cell
- Membrane-bound carriers, such as flavoproteins, cytochromes, and quinones, are important components of electron transport chains
Acquiring Nutrients
- Rapid growth of microbes presents challenges in acquiring nutrients
- Nutrients must enter the cell at high rates, across membranes, in a selective fashion, and often against a concentration gradient
- Both passive and active transport systems are used to acquire nutrients
Passive Transport
- No energy is required for passive transport
- Passive transport requires a gradient from high to low concentration
- Examples of passive transport include passive diffusion and facilitated diffusion
Active Transport
- Energy is required for active transport
- Active transport moves nutrients against a concentration gradient
- ATP or proton motive force is used to drive active transport
- There are two types of active transport: primary and secondary
ABC Transporters
- ABC transporters are a type of primary active transport
- They use ATP to drive the transport of nutrients across the membrane
- ABC transporters are found in all domains of life and can move substances in or out of cells
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Description
This quiz explores the role of enzymes in catalytic reactions, including the actions of superoxide dismutase and catalase. Test your understanding of these biochemical processes.
