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Essential nutrient
Any substance that must be provided to an organism
Macronutrients
Required in large quantities and play principal roles in cell structure and metabolism:
Carbon, hydrogen, and oxygen
Micronutrients
Present in smaller amounts and are involved in enzyme function and maintenance of protein structure:
Trace elements; manganese, zinc, nickel
Organic nutrients
Contain carbon and hydrogen atoms and are usually the products of living things
Simple organic molecules such as methane
Large polymers (carbohydrates, lipids, proteins, nucleic acids)
Inorganic nutrients
An atom or simple molecule that contains a combination of atoms
Metals and their salts (magnesium sulfate, ferric nitrate, sodium phosphate)
Gases (oxygen, carbon dioxide) and water
Found in the earth’s crust, bodies of water, and the atmosphere
Heterotroph vs. Autotroph vs. Phototroph vs. Chemotroph
Heterotroph: must obtain its carbon in an organic form
Autotroph: uses inorganic CO2 as its carbon source
Phototroph: photosynthesizes
Chemotroph: gets energy from chemical compounds
Autotroph Energy Sources: Photoautotrophs vs. Chemoautotrophs
Photoautotrophs:
Photosynthetic
Produce organic molecules using CO2 that can be used by themselves and by heterotrophs
Chemoautotrophs:
Chemoorganic autotrophs: use organic compounds for energy and inorganic compounds as a carbon source
Lithoautotrophs: rely totally on inorganic minerals and require neither sunlight nor organic nutrients
Heterotroph Energy Sources
Parasites:
Derive nutrients from the cells or tissues of a living host
Parasites: pathogens vs. Ectoparasites vs. Endoparasites vs. Obligate parasites
Pathogens: cause damage to tissues or even death
Ectoparasites: live on the body
Endoparasites: live in the organs and tissues
Obligate parasites: unable to grow outside of a living host
Carbon
Proteins, carbohydrates, lipids, and nucleic acids
Hydrogen
Helps cells maintain their pH
Useful for forming hydrogen bonds between molecules
Serves as a source of free energy in respiration.
Oxygen
Major component of organic compounds such as carbohydrates, lipids, nucleic acids, and proteins
Plays an important role in the structural and enzymatic functions of the cell.
Nitrogen
Indispensable to the structure of proteins, DNA, RNA, and ATP
Phosphorus
Key component of nucleic acids and is therefore essential to the genetics of cells and viruses
Found in ATP, serves in cellular energy transfers
Sulfur
Essential component of some vitamins (vitamin B1) and the amino acids methionine and cysteine
How Microbes Eat: Transport Mechanisms
Transport of necessary nutrients occurs across the cytoplasmic membrane, even in organisms with cell walls
Transport Processes in Cells: Passive vs. Active
Passive:
Simple diffusion
Facilitated diffusion
Active:
Carrier-mediated active transport
Cardinal temperatures: Minimum vs. Maximum vs. Optimum temperature
Minimum: lowest temperature that permits growth and metabolism
Maximum: highest temp. that permits growth and metabolism
Optimum: intermediate between the minimum and the maximum that promotes fastest rate of growth and metabolism
Psychrophiles
Obligate with respect to cold
Natural habitats of psychrophilic bacteria, fungi, and algae are lakes, rivers, snowfields, polar ice, and the deep ocean
Rarely pathogenic
Mesophiles
Majority of medically significant microorganisms
Staphylococcus aureus is psychotolerant - can grow in fridge
Thermoduric Microbes
Can survive short exposure to high temperatures but are normally mesophiles
Common contaminants of heated or pasteurized foods
Ex: heat-resistant endospore formers (Bacillus and Clostridium)
Thermophiles
Grow optimally at high temperatures
Live in soil and water associated with volcanic activity, compost piles, and in habitats directly exposed to the sun
Gases; O2
O2 is an important respiratory gas and a powerful oxidizing agent
How Microbes Process Oxygen: Singlet oxygen (O) vs. Superoxide ion (O2-) vs. Hydrogen peroxide (H2O2) vs. Hydroxyl radical (OH-)
Singlet oxygen (O): extremely reactive molecule that can damage and destroy a cell by the oxidation of membrane lipids
Phagocytes
Superoxide ion (O2–): highly reactive
Hydrogen peroxide (H2O2): toxic to cells and used as a disinfectant
Hydroxyl radical (OH–): also highly reactive
How do Microbes Protect Themselves Against Damage from Oxygen By-products?
Most cells have developed enzymes that scavenge and neutralize reactive oxygen by-products
Superoxide ions are converted into ________ ________ by ________ ________
Hydrogen peroxide; Superoxide dismutase
Hydrogen peroxide is converted into harmless ________ and ________ by ________
Water and oxygen; catalase
Aerobes use ….
Examples?
Gaseous oxygen in their metabolism and possess the enzymes needed to process toxic oxygen products
Ex: Most fungi, protozoa, and many bacteria, such as Bacillus species and Mycobacterium tuberculosis
Microaerophiles are harmed by …
Examples?
Normal atmospheric concentrations of oxygen but require a small amount of it in metabolism
Ex: Organisms that live in soil or water or in mammalian hosts, not directly exposed to atmosphere; Helicobacteri pylori, Borrelia burgdorferi
________ ________ do not require oxygen for metabolism but use it when it is present. Examples?
Facultative anaerobes
Ex: Many gram-negative bacteria, staphylococci
__________ lack the metabolic enzyme systems for using oxygen in respiration. Examples?
Anaerobes; many oral bacteria, intestinal bacteria
________ ________ do not utilize O2 but can survive and grow to a limited extent in its presence
Aerotolerant anaerobes
________ are organisms that grow best at a higher CO2 tension than is normally present in the atmosphere; Example?
Capnophiles; Steptococcus pneumoniae
pH is the degree of ________ or ________ of a solution. What is the pH of pure water? Physiological? Decreasing toward 0 means …. Increasing …
Acidity or alkalinity; 7; 7.4; Acidity increases; Alkalinity increases
Helicobacter decomposes urine and creates ________ conditions
Alkaline
Osmophiles live in habitats with ________ solute concentration
High
________ prefer high concentrations of salt
Halophiles
Obligate vs. Facultative halophiles
Obligate halophiles: Halobacterium and Halococcus grow optimally at solutions of 25% NaCl but require at least 9% NaCl
Facultative halophiles: remarkably resistant to salt, even though they do not normally reside in high salt environments
Staphylococcus aureus can grow on NaCl media ranging from 0.1% to 20%
Nonphotosynthetic microbes tend to be damaged by …
The toxic oxygen products produced by contact with light
________ use visible light rays as an energy source
Phototrophs
Barophiles thrives in ________ pressure zones
High
Symbiosis and Symbionts
Two organisms live together in a close partnership; members of a symbiosis
What are the 3 types of symbiosis?
Mutualism, commensalism, and parasitism
Symbiosis: Mutualism
Organisms live in an obligatory but mutually beneficial relationship
Symbiosis: Commensalism
Partner called the commensal receives benefits, while its partner is neither harmed nor benefited
Symbiosis: Parasitism
The host organism provides the parasitic microbe with nutrients and a habitat; host suffers from the relationship
Antagonism
Association between free-living species that arises when members of a community compete
Ambiosis
Producing inhibitory compounds (antibiotics) into the surrounding environment which inhibit or destroy another microbe in the same habitat
What is the interrelationship between two organisms that benefits them but is not necessary for survival called?
Synergism
Binary fission is when …
One cell becomes two
Steps in Binary Fission
A young cell
Chromosome is replicated and new and old chromosomes move to different sides of cell
Protein band forms in center of cell
Septum formation begins
When septum is complete, cells are considered divided. Some species will separate completely, while others remain attached, forming chains or doublets
What is generation?
Increasing the population by a factor or two
A predictable pattern of a bacterial population growth in a closed system is a …
Growth curve
Stages in normal grown curve (4)
Lag
Exponential growth
Stationary growth
Death phase
The ________ phase is a “flat” period of growth due to:
Lag; Cells not multiplying at max rate, pop of cells is sparse or diluted that sampling misses them
The ________ growth (________) phase is when the growth curve increases geometrically
Exponential; logarithmic/log
The ________ growth pase is when cell birth and cell death rates are equal, cell division rate is slowing down
Stationary
The ________ phase is when cells begin to die at an exponential rate
Death
Viable nonculturable state is when ….
Many cells in a culture in the death phase stay alive but are dormant
Microbes in the exponential growth phase are more vulnerable to …
Antimicrobial agents and heat
Cells in the growth phase are more vulnerable to conditions that disrupt …
Cell metabolism and binary fission
In general, actively growing cells are more vulnerable to …
Growth inhibition and destruction
A clear nutrient solution becomes …, or cloudy, as microbes grow in it
Turbid
Metabolism pertains to all …
Chemical reactions and physical workings of the cell
Anabolism vs. Catabolism
Anabolism: Requires energy input
Catabolism: Releases energy
Anzymes are biological …
Catalysts
Catalysts increase the ________ of chemical reactions and are not …
Rate; consumed in the process
Holoenzyme vs. Apoenzyme vs. Cofactors
Holoenzyme: is a combination of a protein and one or more cofactor
Apoenzyme: protein portion of a holoenzyme
Cofactors: either organic molecules called coenzymes or inorganic elements (metal ions)
The need of microorganisms for ________ ________ arises from their roles as cofactors for enzymes. Examples?
Trace elements; iron, copper, magnesium, zinc, cobalt, selenium, etc
________ ________ work in conjunction with an apoenzyme
Organic compounds
Many coenzymes are derived from ________
Vitamins
Activity of enzymes are influenced by …
The cell’s environment
Changes in the normal conditions cause enzymes to be …
Unstable or labile
Denaturation is when … causes …
Weak bonds that maintain the native shape of the apoenzyme are broken; distortion
Enzyme repression vs. Induction
Enzyme repression
Genetic apparatus responsible for replacing enzymes is automatically suppressed
Enzyme induction
Enzymes appear (are induced) only when suitable substrates are present
E. coli enables the organism to utilize …
A variety of nutrients
Energy is stored as …
ATP
Exergonic vs. Endergonic reactions
Exergonic - releases energy as it goes forward
Endergonic - require input of energy
Energy released during exergonic reactions is stored in … in ATP
High-energy phosphate bonds
Aerobic respiration utilizes … relies on …
Glycolysis, Krebs cycle, and the respiratory chain; free oxygen as the final electron and hydrogen acceptor
Anaerobic respiration involves … uses …
Glycolysis, Krebs cycle, and the electron transport chain; ocidized compounds as terminal electron acceptors
Fermentation is the …
Incomplete oxidation of glucose
Fermentation: Oxygen is ________
Not required
Fermentation: Organic componds are …
Terminal electron acceptors
A chain of special redox carriers are embedded in the …
Cytoplasmic membrane in bacteria
In the final step of the aerobic respiration, … producing water
Oxygen accepts electrons and hydrogen
Aerobes have ________ enzymes to deal with toxic oxygen products (Steptococcus)
Neutralizing
The terminal step in anaerobic respiration utilizes … rather than free oxygen, as the final electron acceptor
Inorganic, oxygen-containing ions
________ ________ catalyzes the removal of oxygen from nitrate, leaving nitrite and water as products
Nitrate reductase
Denitrification: Some species of … possess enzymes that can further reduce nitrite to nitric oxide (NO), nitrous oxide2(N O) , and even nitrogen gas2(N )
Pseudomonas and Bacillus
Fermentation is the incomplete oxidation of glucose or other carbohydrates in the ..
Absence of oxygen
Fermentation uses … as the terminal electron acceptors
Organic compounds
Fermentation yields a ________ amount of ATP
Small
The methods of microbial control used outside of the body are designed to result in four possible outcomes …
Sterilization - autoclave
Disinfection - not bacteria endospores; bleach, iodine, heat
Decontamination (also called sanitization); soaps, detergents
Antisepsis - living tissues; alcohol, surgical hand scrubs
Bacterial Endospores
Have been considered the most resistant microbial entities
The goal of any sterilization process is the destruction of …
Endospores
Chemical that destroys bacteria except for those in the endospore stage
Bacteristatic
Fungicide vs. Virucide vs. Sporicide vs. Germicide/microbicide
Fungicide: chemical that can kill fungal spores, hyphae, yeasts
Virucide: chemical known to inactivate viruses, especially on living tissue
Sporicide: an agent capable of destroying bacterial endospores
Germicide/microbicide: chemical agents that kill microorganisms
The growth of microorganisms in the blood and other tissues
Bacteremia
Antiseptics: chemical agents applied ________ to exposed body surfaces, wounds, and surgical incisions
Directly