-
–Nutrients
- are acquired from the environment
- and used for cellular activities
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•Essential nutrient:
any substance that must be provided to an organism
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•Macronutrients
- –Required in relatively large quantities
- and play principal
- roles in cell structure and metabolism
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•Micronutrients (trace elements)
- –Present in smaller amounts
- and involved in
- enzyme function and maintenance of protein structure
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•Inorganic nutrients
- Simple
- molecule that contains a combination of atoms other than carbon and hydrogen
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•Organic nutrients
Contain carbon and hydrogen atoms and usually the product of living things
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•Growth factor
- –An organic compound that cannot be
- synthesized by an organism and must be provided by the environment
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•Autotroph
- “Self-feeder”
- Organism that uses inorganic CO2 as
- its carbon source
- Have the capacity to convert CO2 into
- carbon compounds
- Not dependent on other living things
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•Heterotroph
- An organism that must obtain its carbon in organic form
- Dependent on other life forms
- Most carbon sources exist in a form that is simple enough for absorption
- Many carbon sources must be digested by the cell in order to be absorbed
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Saprobic
Microorganisms
- Decomposers of plant litter, animal matter, and dead microbes
- have a rigid cell wall and cannot engulf large particles of food
- Release enzymes into the environment to digest food
-
Parasitic
Microorganisms
- Live on or in the body and cause some degree of harm to the host
- pathogens
- –Ectoparasites: live on the body
- –Endoparasites: live in organs and tissues
- –Intracellular
- parasites: live within cells
- –Obligate parasites: unable to live outside of a living host
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•Diffusion
- movement of molecules in a gradient from
- an area of higher density to an area of lower density
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•Osmosis:
- the movement of water across a selectively
- permeable membrane
-
•Facilitateddiffusion
- Mediated transport
- Utilizes a carrier protein that will bind a specific substance
- Binding changes the conformation of the carrier proteins so that the substance is moved
- across the membrane
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•Active Transport:
- Transports nutrients against a
- concentration gradient or with a concentration gradient at a faster rate
- Presence of specific membrane proteins
- Expenditure of energy
-
•Optimum
temperature
- –Promotes
- the fastest rate of growth and metabolism
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•Singlet oxygen (O)
- –Extremely reactive molecule produced both by living and nonliving processes
- –Produced by phagocytes to kill invading microbes
- –Buildup of singlet oxygen and the oxidation of membrane lipids and other molecules can
- damage or destroy a cell
-
•Superoxide ion (O2-), hydrogen peroxide (H2O2), and hydroxyl radicals (OH-)
- –Destructive metabolic byproducts of
- oxygen
- –Cells use enzymes to scavenge and
- neutralize them
- •Catalase
- •Superoxide dismutase
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•Aerobe
- –Can
- use gaseous oxygen in its metabolism
- –Possesses
- the enzymes needed to process toxic oxygen products
- Obligate aerobe:
- an organism that cannot grow without oxygen
-
•Microaerophile
- –Does not grow at normal atmospheric
- conditions of oxygen
- –Requires a small amount of oxygen
- in its metabolism
- -live in a habitat that provides a small amount of oxygen but is not directly exposed to the atmosphere
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•Facultative anaerobe
- –An aerobe that does not require oxygen for its metabolism
- –Capable of growth in the absence of oxygen
- –Metabolizes by aerobic respiration when oxygen is present
- –Adopts fermentation when oxygen is absent
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•Anaerobe
- –Lacks the metabolic enzyme systems
- for using oxygen in respiration
- –Strict or obligate anaerobes
- cannot tolerate free oxygen and will die in its presence
- •Live in highly reduced habitats
- such as lakes, oceans, and soil
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•Aerotolerant anaerobes
- –Do not utilize oxygen
- –Can survive and grow to a limited
- extent in its presence
- –Not harmed by oxygen because they
- possess alternative mechanisms for breaking down peroxides and superoxide
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•pH:
- the degree of acidity or alkalinity of a
- solution expressed on a scale from 0 – 14
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•Obligate acidophiles
- –Require an acidic environment for growth
- Molds and yeasts tolerate acid and are common spoilage agents of pickled foods
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•Alkalinophiles
- –Live in hot pools and soils that
- contain high levels of basic minerals
- –Bacteria that decompose urine create alkaline conditions
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•Obligate Halophiles
- –Require high concentrations of salt
- for growth
- –Have significant modifications to
- their cell walls and membranes
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•Halotolerantor Facultative halophiles
- –Resistant to salt, even though they
- do not normally reside in high-salt environments
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•Protective measures against radiation
- –Yellow carotenoid pigments absorb
- and dismantle toxic oxygen
- –Other microbes use enzymes to
- overcome the damaging effects of UV radiation on DNA
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