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Foundations of Microbiology 8th ed


process by which chemical substances (nutrients) are acquired from the environment and used in cellular activities

Essential nutrients

must be provided to an organism.
2.micronutrients or trace elements


required in large quantities;play principal roles in cell structure and metabolism(proteins, carbohydrates, nucleic acid)


(trace elements)-required in small amts; involved in enzyme function and maintenance of protein structure(manganese, zinc, nickel)metals

2 types of nutrients

1. organic nutrients
2. inorganic nutrients

organic nutrients

C & H atoms-usually products of living things.(methane, carbohydrates, lipids, proteins, nucleic acids)

inorganic nutrients

NO C & H - atom or molecule that contains a combination of atoms other than carbon and hydrogen(metals,and their salts-magnesium sulfate, ferric nitrate, sodium phosphate), gases (oxygen, carbon dioxide) and water.

chemical analysis of cell contents

70% water
proteins-main macromolecule/most abund. in cell
96% other elements

source of essential nutrient-carbon source

1.Heterotroph-obtain by an organic form made by other living organism(proteins, carbohydrates, lipids, and nucleic acids.
2. Autotroph- photosynthesis,uses CO2(from atmoshpere), an inorganic gas as carbon source
ex. archaea- use inorganic chemicals coming out of vents


obtain CARBON SOURCE by an organic form made by other living organism(proteins, carbohydrates, lipids, and nucleic acids.


obtain CARBON SOURCE by;photosynthesis,uses CO2(from atmoshpere), an inorganic gas as carbon source
ex. archaea- use inorganic chemicals coming out of vents

Growth factors

Essential organic nutrients:
organic compounds that cannot be synthesized by an organism because they lack the genetic and metabolic metabolic mechanisms to synthesize them.
-must be provided as a nutrient(essential amino acids, vitamins)

nutritional types

Carbon source-heterotroph,autotroph
Energy source-chemotroph,phototroph

source of essential nutrient-energy source

1.Chemotroph-gain energy from chemical compounds(humans)
2.Phototrophs-gain energy through photosynthesis


gain energy from chemical compounds(humans)


gain energy through photosynthesis

autotrophs and their energy source

1.oxygenic photosynthesis-algae,plants
2.anoxygenic photosynthesis-green & purple sulfur
2.chemoautotrophs-(lithoautotrophs) survive totally on inorganic substances(methanogens, a kind of chemoautotroph, produce methane gas under anaerobic conditions.

heterotrophs and their energy source

majority are chemoheterotrophs
-aerobic respiration
1. saprobes-free living microorganisms that feed on
organic detritus from dead organisms(decomposers)
-opportunistic pathogen
-facultative parasite/not obligate
2.parasites-derive nutrients from host(living host)
-some are obligate parasites


sunlight or organic matter (purple and green sulfur photosynthetic bacteria)


sunlight-photosynthetic organisms, such as algae, plants, cyanobacteria


simple inorganic chemicals, only certain bacteria, such as methanogens, deep-see vent bacteria


metabolic conversion of the nutrients from other organisms,protozoa, fungi, many bacteria, animals
1. saprobe-organic matter of dead organisms (decomposers)
2. parasite- tissues fluids of living host(various parasites & pathogens;can be bacteria, fungi,protozoa, animals

2 types of movement of chemicals across the cell membrane

1. passive transport-NO ATP, moves in gradient areas of higher concentration-areas of lower conc.
2. osmosis-diffusion of water
3.facilitated diffusion-requires carrier(protein channel)
2. active transport-ATP and carrier proteins(gradient INDEPENDENT) translocation-transported molecule chemically altered as enter cell.
2.bulk transport-endocytosis,exocytosis,pinocytosis, bring in a lot of substance at one time
3.carrier mediated active transport-membrane proteins (permeases) have attachment sites for essential nutrient molecules. (ex.ATP or PROTON MOTIVE FORCE)


bringing substances into the cell through a vesicle or phagosome
1.phagocytosis-ingests substances or cells(when vacuole fuses w/ lysosome)
2.pinocytosis-ingests liquids


totality of adaptions organisms make to their habitat

Environmental factors affect the function of

metabolic enzymes (proteins)

Factors that influence microbes

2.oxygen requirements
4.Osmotic pressure
5.Barometric pressure

3-cardinal temperatures

1.minimum temperature-lowest temp that permits a microbe's growth and metabalism
2.maximum temperature-highest temp that permits a microbe's growth and metabalism
3.optimum temperature-promotes the fastest rate of growth and metabolism

3-temperature adaption groups

psychrophiles-cold, freezing
mesophiles-most humans

toxic products of oxygen

singlet oxygen,superoxide ion,peroxide, hydroxyl radicals

enzymes that neutralize toxic products of oxygen

superoxide dismutase, catalase

categories of oxygen requirments

Aerobe,obligate aerobe,facultative anaerobe,microaerophilic, anaerobe, obligate anaerobe, aerotolerant anaerobes


utilizes oxygen and can detoxify it

obligate aerobe

cannot grow without oxygen

facultative anaerobe

utilizes oxygen but can also grow in its absence


requires only a small amount of oxygen


does not utilize oxygen

obligate anaerobe

lacks the enzymes to detoxify oxygen os cannot survive in an oxygen environment

aerotolerant anaerobes

do not utilize oxygen but can survive and grow in its presence


grows best at higher CO2 tensions than normally present in the atmosphere(less oxygen more CO2)

effects of Ph

acidophiles-grow in extreme acid pH
alkalinophiles-grow in extreme alkaline pH


grow at a pH between 6-8


grow at extreme acid pH


grow at extreme alkaline pH


require a high concentration of salt


do not require high concentration of solute but can tolerate it when it occurs


can survive under extreme pressure and will rupture if exposed to normal atmospheric pressure

microbial asssociations

symbiotic-organisms live in close nutritional relationships;required by one or both members
nonsymbiotic-organisms are free-living;relationships not required for survival


organisms live in close nutritional relationships;required by one or both members


organisms are free-living;relationships not required for survival

3 types of symbiotic associations

1.mutualism-obligatory, dependent;both members benefit (both benefit)
2.commensalism-commensal benefits;other member not harmed (1 gains/other not harmed)
3.parasitism-obligate,parasite is dependent and benefits;host harmed (1 gains/other harmed)

2 types of nonsymbiotic associations

1.synergism-members cooperate and share nutrients,produce result that none of them could do alone.
2.antagonism-some members are inhibited or destroyed by others(competition) antibiosis

interrelationship between microbes and humans

human body is a rich habitat for symbiotic bacteria, fungi, and a few protozoa-NORMAL MICROBIAL FLORA
-commensal, parasitic,synergistic


human body is a rich habitat for symbiotic bacteria, fungi, and a few protozoa


result when organisms attach to a substrate by some form of extracellular matrix that binds them together in complex organized layers

quorum sensing

communicate and cooperate in the formation and function of biofilms(use chemical signals) cooperate to produce enzymes

inducer molecule

in quorum sensing-stimulates expression of a particular gene and synthesis of a protein product, such as an enzyme

2 levels of microbial growth

cellular level-increase in size

division of bacterial cells occurs mainly through

binary fission(transverse)

binary fission

(transverse)-parent cell enlarges, duplicates its chromosome, and forms a central transverse septum dividing the cell into 2 daughter cells
-doubles each time(exponential generation time)

exponential generation time

the doubling of cells each time in binary fission

generation or doubling time

time required for a complete fission cycle
minutes or days

exponential growth

each new fission cycle increases the population by a factor of 2


Nf=total # cells in population
ni=starting # cells
n=denotes generation time(specific for organism)
2n=number of cells in that generation

population growth curve

1.lag phase-flat,period of adjustment,enlargement, little growth
2.exponential growth phase
3.stationary phase
4.death phase

methods of analyzing population growth

1.viable plate count
3.enumeration of bacteria-viable colony count,direct cell count

growth curve

in laboratory studies, populations typically display a predictable pattern over time


all chemical and physical workings of a cell

2 types of chemical reactions

1.catabolism-release energy,degredation
2.anabolism-needs energy,biosynthesis(making building)

energy of activation

enzymes are biological catalyst that increase the rate of a chemical reaction by lowering the ___________.

simple enzyme

consist of protein ALONE

conjugated enzyme

holoenzyme-contain protein and nonprotein molecules


protein portion of enzyme


nonprotein portion of enzyme (INORGANIC ION)
act as carriers to assist the enzyme in its activity.
1.metallic cofactors-INORGANIC ION; iron,copper, magnesium(trace elements)
2.coenzymes-ORGANIC MOLECULES;vitamins(growth factors)

coenzyme cofactors

ORGANIC MOLECULES;vitamins (growth factors)

metallic cofactors

INORGANIC ION; iron,copper, magnesium(trace elements)

catalase enzyme

breaks down hydrogen peroxide
metallic cofactor required-iron

oxidase enzyme

adds electrons to oxygen
metallic cofactor required-iron,copper

hexokinase enzyme

transfers phosphate to glucose
metallic cofactor required-magnesium

urease enzyme

splits urea into an ammonium ion
metallic cofactor required-nickel

nitrate reductase enzyme

reduces nitrate to nitrite
metallic cofactor required-molybdenum

DNA poymerase complex

synthesis of DNA
metallic cofactor required-zinc and magnesium

active site

catalytic site-site for substrate binding

induced fit

a temporary enzyme-substrate union occurs when substrate moves into active site
-appropriate reaction occurs;product is formed and released

location of enzyme action



transported extracellularly, where they break down large food molecules or harmful chemicals


retained intracellularly and function there (majority)

regularity of enzyme action

1.constitutive enzymes
2.regulated enzymes

constitutive enzymes

always present, always produced in equal amounts or at equal rates, regardless of the amount of substrate

regulated enzymes

not constantly present;production is turned on (induced)or turned off(repressed)in response to changes in the substrate concentration

synthesis or condensation reactions

release water,anabolic reactions to form covalent bonds between smaller substrate molecules, require ATP, release 1 molecule of water for each bond formed

hydrolysis reactions

need water, catabolic reactions that break down substrates into small molecules;requires the input of water to break bonds


chemically UNstable enzymes
caused by;
changes to temperature, pH, osmotic pressure of organisms habitat
Ex. denaturation-weak bonds that maintain the shape of the apoenzyme are broken


weak bonds that maintain the shape of the apoenzyme are broken

multienzyme systems

metabolic pathways
product of substrate input=substrate for next enzyme

competitive inhibition`

substance that resembles the normal substrate competes with the substrate for the active site

noncompetitive inhibition

(allosteric inhibition)
enzymes are regulated by the binding of molecules other than the substrate away from the active site

enzyme repression

inhibits at the genetic level by controlling synthesis of the enzymes

enzyme induction

enzymes are made only when suitable substrates are present


the capacity to do work or to cause change

endergonic reactions

(anabolic)-consume energy
energy + A + B--enzyme--C

exergonic reactions

(catabolic)-release energy
X + Y--enzyme--Z + energy

energy released in temporarily stored in high energy ______molecules.

the energy of these molecules is used in endergonic cell reactions.

redox reactions

-always occurs in pairs
-electron acceptor and electron donor
-process salvages electrons & their energy
-released energy can be captured to phosphorylate ADP or another compound

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