mirco test 1

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1

microbiology

the study of organisms too small to be seen by unaided eye

2

living members of the microbial world

bacteria, archaea, alga, fungi, protozoan

3

nonliving members of the microbial world

viruses, viroids, prions

4

6 applications of microbiology/microbes to our lives

1. food production
2. biodegradation
3. biotechnology
4. genetic engineering
5. synthesis of commercially valuable products
6. medical microbiology

5

when was microbiology developed?

in 1674 with the discovery of microscopes and microbes

6

Antony van Leeuwenhoek

invented microscope. observed animalcules (today known as microorganism and microbes)

7

Robert Hooke

also credited with the discovery of microbes and microscopes. describes common bread mold in 1665

8

Francesco Redi

disproved theory of spontaneous generation by demonstrating that worms on rotting meat came from eggs of flies landing on meat (1668)

9

Louis Pasteur

disproved theory of spontaneous generation by demonstrating that air is filled with microorganisms and contact of broth with microorganisms is required for the growth of microorganisms in the broth. also developed swan-necked flasks

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John Tyndall

provided by further experiments that Pasteur was correct

11

Ferdinand Cohn

discovered endospores

12

Robert Koch

demonstrated that anthrax is caused by bacteria. developed pure culture techniques

13

Joseph Lister

started the use of antiseptics in surgery

14

Hans Christian Gram

developed gram staining technique

15

Alexander Fleming

discovered the first antibiotic, penicillin

16

golden age of microbiology

1875-1903

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How do we study microorganisms?

1. by observing them using microscopes
2. by making it easier to see cell structures using dyes or stains
3. by growing them in the lab using artificial culture media

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immersion oil

used with the 100 X objective lens to maximize resolution

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contrast

the ability of a microscope to make an image clear

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resolving power

measurement of how clear the image is

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magnification

measurement of how big an image can be

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light microscopes

light passes through a specimen and then through a series of magnifying lenses, magnifying the image up to 1000X. has 6 different types

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electron microscopes

beams of electrons are passed through specimen and then a series of electromagnetic lenses, magnifying the image more than 100000X. it has 2 types

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atomic force microscopes

a very sharp probe moves across the surface of the specimen, feeling the bumps and valleys of the atoms. it can produce detailed images of individual atoms on a surface. it has a resolving power much greater than that of EM

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basic dyes

most commonly used dyes

ex. methylene blue, crystal violet, safranin

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acidic dyes

sometimes used dyes. used in negative staining

ex. india ink or nigrosine

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simple staining

a single dye is used to visualize bacteria

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differential staining

two dyes are used to distinguish between different groups of bacterial. the two most frequently used techniques are gram staining and acid-fast staining

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special staining

one, two or more dyes are used to stain specific structures inside or outside the cells

ex. capsule staining, flagellar staining, endospore staining

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fluorescent labeling

fluorescent dyes are used to stain total cells, a subset of cells, or certain proteins on cell surface

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gram staining

type of differential staining. most commonly used staining technique in microbiology. it is used to identify bacteria belonging to two major groups: gram positive and gram negative. it is based on fundamental difference in cell wall structure of bacteria belonging to these groups

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acid-fast staining

type of differential staining. it is used to detect bacteria of the genus Mycobacterium. it differentiates acid-fast bacteria from non-acid fast bacteria. acid-fast have high concentrations of mycolic acid in their cell wall

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coccus/cocci

spherical

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bacillus/bacilli

rod-shaped

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coccobacillus/coccobacilli

short rods

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vibrio

short curved rods

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spirillum/spirilla

curved rods forming spirals

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spirochetes

long helical cells with flexible cell walls

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pleomorphic

many shapes

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strepto-

chain

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diplo-

pair

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tetrads

groups of four

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sarcinae

cubical packets

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What structures are prokaryotic cells made up of?

1. cell envelope- cytoplasmic membrane, cell wall, capsule and slime layer
2. other structures outside the cell- flagella and pili
3. cytoplasm
structures inside the cell- nucleoid, plasmids, endospores, and others

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cytoplasmic membrane

STRUCTURE: a thin delicate structure that surrounds the cytoplasm. it is made up of two layers of lipid molecule (phospholipid bilayer) embedded with proteins.

FUNCTION: it is selectively permeable allowing the movement of gases water and small molecules across the PL Bilayer through simple diffusion and osmosis, the proteins embedded serve as gates for the transport of larger molecules into the cell, helps to produce energy from food through the ETC

46

electron transport chain

1. electrons are transferred from one protein to the other in the chain
2. in the process, proteins release protons to the outside of the membrane
3. the collection of protons immediately outside the membrane forms a force called proton motive force
4.the PMT is used by the cells as a source of energy

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cell wall

STRUCTURE: a strong and slightly rigid structure outside the cytoplasmic membrane

FUNCTION: gives shape to the cell, peptidoglycan provides strength to the cell wall, the outer membrane blocks many toxic compounds from entering the cell

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peptidoglycan

alternating series of subunits NAG and NAM joined to form glycan chains

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gram-positive cell wall

thick peptidoglycan layer, teichoic acid present, no outer membrane, no lipopolysaccharide, no porin proteins

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gram-negative cell wall

thin peptidoglycan layer, teichoic acid absent, outer membrane present, lipopolysaccharide present, porin proteins present

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capsules and slime layers

STRUCTURE: a distinct and regular gel-like layer outside the cell wall; an irregular gel like layer outside the cell wall. both composed of either polysaccharides or polypeptides

FUNCTION: help the bacteria attach to different surfaces, avoid the natural defense system of the host

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flagella

STRUCTURE: long protein structures that originate from the cytoplasmic membrane and protrude out from the cell surface

FUNCTION: help the bacteria move from one place to another. carries out the movement of chemotaxis

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pili

STRUCTURE: shorter and thinner than flagella. also move much slower

FUNCTION: some help bacteria cells attach to cell surfaces, some help bacterial cells move on solid surfaces, the sex pilus helps function in reproduction by joining two bacterial cells for transfer of DNA

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chromosome

known as the nucleoid. a single, circular, double-stranded DNA molecule. tightly packed in the cell. contains all the genetic information required by the cell

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plasmids

circular, double-stranded DNA molecules that can multiply independent of the chromosome. much smaller than the chromosome. most carry genes for antibiotic resistance

56

endospores

a unique type of cells produced by some bacteria. can remain dormant for a long time. they are highly resistant to high temperature, desiccation, and toxic chemicals

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taxonomy of prokaryotes

the grouping of microorganisms based on similar properties: classification, identification, and nomenclature

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how are prokaryotes classified?

1. phenotypic classification- based on morphological features and physiological characteristics (shape, size, arrangement, ect.)

2. molecular or genotypic classification- based on similarity in the nucleotide sequences (DNA and RNA)

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3 domains of living organisms

1. Bacteria ( P)
2. archaea ( P)
3. eucarya (E)

60

species

a basic unit: group of closely related isolates or strains

61

genus

a collection of similar species

62

how are prokaryotes identified?

1. phenotypic characteristics: microscopic morphology, culture characteristics, metabolic properties, unique proteins and carbohydrates, types and amounts of fatty acids

2. molecular or genotypic characteristics: the similarity in unique nucleotide sequences, the similarity in rRNA and rDNA sequences

63

microscopic morphology

determines the size, shape, and staining characteristics. gives quick information, sometimes enough to make a presumptive diagnosis

64

culture characteristics

looks at the morphology of bacterial colonies growing on culture media

65

metabolic characteristics

performs biochemical tests on bacterial samples

66

dichotomous key

a flowchart of tests that give either a positive or negative result. a number of biochemical tests are performed on the bacteria to identify them to the species level

67

how to bacteria multiply?

prokaryotic cells divide by binary fission

68

exponential growth

when cells are actively dividing, the population doubles after each division

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generation time

the time it takes for a bacterial cell to double. it depends on the bacterial species and growth conditions

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how do bacteria grow?

1. singly
2. in mixed groups--by forming biofilms

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biofilms

communities of different bacterial species encases in polysaccharides known as EPS

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the importance of biofilms on human health

1. dental plaque leads to tooth decay, gum disease
2. many infections are complicated biofilms (ear infections)
3. more resistant to treatment with antimicrobial agents

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pure culture

a population of bacteria that developed from a single bacterial cell. it is very useful in identifying and studying particular species. needs aseptic techniques (sterile)

74

batch cultures

considered closed systems as nutrients are not renewed and wastes are not removed from the culture

75

what are the phases of the bacterial growth curve?

1. lag phase
2. exponential (log) phase
3. stationary phase
4. death phase
5. decline phase

76

lag phase

phase in which the number of cells does not increase. the cells being synthesizing enzymes required for growth

77

exponential (log) phase

phase in which the cells divide at a constant rate. generation time is measured in this phase. bacteria are most sensitive to antibiotics in this phase

78

stationary phase

phase in which nutrient levels in the medium becomes too low to sustain growth. total numbers of bacteria remain constant. some bacteria die, others grow

79

death phase

phase in which the total number of viable cells decrease. bacterial cells die at a constant rate

80

decline phase

phase in which some fraction of bacteria may survive and become adapted to tolerate worsened conditions

81

continuous cultures

also known as open systems. bacterial growth is maintained at exponential phase by constantly adding nutrients to the culture medium and removing wastes from the culture medium

82

what are the environmental factors that affect the growth of bacteria?

1. temperature requirements
2. oxygen requirements
3. pH requirements
4. water availability

83

psychrophile

temperature range: -5 C to 15 C

ex. pseudomonas

84

psychrotroph

temperature range: 20 C to 30 C
optimal growth temperature: above 25 C

ex. listeria

85

mesophile

temperature range: 25 C to 45 C
optimal growth temperature: 37 C

ex. staphylococcus aurous; most disease causing bacteria belong to this group

86

thermophile

temperature range: 45 C to 70 C

ex. bacilius thermophius

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hyperthermophile

temperature range: 70 C to higher

ex. bacilius thermophilus stereothermophilius; belong to archaea

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obligate aerobe

grows only when oxygen is available. requires oxygen for respiration. produces superoxide dismutase and catalase

89

facultative anaerobe

grows best when oxygen is available, but also grows without it. uses oxygen for respiration if available. produces superoxide dismutase and catalase

90

obligate anaerobe

cannot grow when oxygen is present. does not use oxygen in the energy harvesting process. does not produce superoxide dismutase and catalase

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microaerophile

grows only if small amounts of oxygen are available. requires oxygen for respiration. produces some superoxide dismutase and catalase

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aerotolerant anaerobe

grows equally well with or without oxygen. it does not use oxygen in the energy harvesting process. produces superoxide dismutase but not catalase

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neutrophiles

grow optimally at pH 5 to 8, optimum pH is near 7. most microbes belong to this group

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acidophiles

grow optimally at pH below 5.5

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alkaiphiles

grow optimally at pH above 8.5

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halotolerant

withstand up to 10% salt concentrations

ex. staphylococcus

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halophiles

require high salt concentrations (up to 3%)

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extreme halophiles

require extremely high salt concentrations (up to or greater than 9%)

99

what are the nutritional factors that affect the growth of bacteria?

1. required elements
2. growth factors
3. energy sources

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required elements

major elements that make up cell components

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heterotrophs

bacteria that use organic carbon

102

autotrophs

bacteria that use inorganic carbon as CO2 (by carbon fixation)

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growth factors

certain molecules that some bacteria cannot synthesize and need to obtain from external sources

amino acids, vitamins, purines, pyrimidines

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non-fastidious bacteria

bacteria that can synthesize their own growth factors, and therefore, have wide metabolic capabilities

ex. E. coli

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fastidious bacteria

bacteria that have complicated nutritional systems

ex. Meisseria gonorrheae

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phototrophs

bacteria that obtain energy from sunlight

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chemotrophs

bacteria that extract energy from chemicals

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photoautotrophs

energy source: sunlight
carbon source: CO2

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photoheterotroph

energy source: sunlight
carbon source: organic compounds

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chemolithoautotroph

energy source: inorganic chemicals
carbon source: CO2

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chemoorganohetertroph

energy source: organic compounds (sugars, amino acids, ect.)
carbon source: organic compounds

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general purpose media

culture media that support the growth of all bacteria that do not have specific growth requirements

113

complex media

culture media that contain a variety of ingredients

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chemically defined media

culture media that are composed of exact amounts of pure chemicals

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selective media

special type of culture media that inhibits growth of certain species

116

differential media

special type of culture media that contains substance that microbes change in identifiable way

117

Joseph Lister

british physician who started the use of antiseptics in surgery

118

sterilization

the removal of all microorganisms--including endospores and viruses

119

disinfection

the elimination of most pathogens. some viable microbes remain

120

disinfectants

used on inanimate objects- may be called biocides, germicides, bactericides

121

antiseptics

used on living tissues

122

pasteurization

the brief heating to reduce the number of spoilage organisms, and to destroy pathogens. used on foods and inanimate objects

123

what are methods of control of microbial growth?

1. physical
2. chemical
3. other

124

physical control methods

1. using heat to destroy microorganisms and viruses: incineration, autoclaving, boiling, pasteurization
2. using filtration to remove microbes from liquid or air: membrane filters, HEPA filters
3. using radiation to destroy microbes: ionizing radiation and UV radiation

125

chemical control methods

using germicidal chemicals

126

alcohols

chemical control method which is antiseptics or disinfectants. organic solvents. destroy cells by coagulating essential proteins and damaging lipid membranes. kill vegetative cells of bacteria and fungi, but do not destroy endospores and some naked viruses

127

aldehydes

chemical control method which is a disinfectant. it destroys microbes by inactivating proteins and nucleic acids.

ex. formaldehyde, glutaraldehyde, and orthophthalaldehyde

128

ethylene oxide gas

chemical control method which is a disinfectant. used to sterilize heat or moisture sensitive items. it destroys microbes by reacting with proteins

129

halogens

chemical control method which is a disinfectant. it destroys microbes by damaging proteins and cell components.

ex. chlorine and iodine

130

chemical preservatives

food preservatives that are non-toxic and safe

ex. weak organic acids, nitrate and nitrite

131

low-temperature storage

refrigeration and freezing--hold bacteria at non growing phase

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reducing available water

salt and drying

133

how do we choose the appropriate control method?

1. the type of microbe
2. the population size of microbes
3. the type of object
4. the level of toxicity, activity, and effectiveness of the germicidal chemical
5. the cost of the treatment process

134

mycology

the study of fungi

135

mycoses

diseases caused by fungi

superficial- pertaining to the skin (external)
systemic- of the organs (internal)

136

yeasts

single-cellular fungi

137

molds

multi-cellular fungi

138

hyphae

threadlike filaments that make up fungi

139

mycelium

a visible mass of hyphae

140

spores

the reproductive organ of fungi. they germinate into hyphae

141

sporangia

a sac-like structure that the spores are produced in

ex. aspergillus and rhizopus

142

conidia

asexual spores borne on hyphae; produced by both fungi and bacteria of the genus streptomyces

143

what are two ways that fungi are useful?

1. some produce antimicrobial medicines-- penicillin
2. some can be used to produce important molecules such as human insulin and hepatitis B vaccine

144

what are three ways that fungi are harmful?

1. some can grow on or in the body and cause diseases
2. some cells or spores may cause allergic reactions
3. some produce toxins that are harmful if ingested-- aspergillus can cause cancer

145

candidial skin infection

fungal disease caused by candida albicans (yeast) on the skin

146

vulvovaginal candidiasis

fungal disease caused by candida albicans (yeast) of the vagina

147

malaria

disease caused by the protozoan plasmodium

148

giardia

disease caused by the protozoan giardiasis

149

african sleeping sickness

disease caused by the protozoan trypanosoma

150

amebiasis (diarrhea)

diseased caused by the protozoan entamoeba

151

hookworm disease

infection from a hookworm (necator americanus and ancylostoma duodenale)

characteristics: anemia, weakness, fatigue, physical and intellectual disability in children

152

tapeworm disease

infection from either a fish tapeworm or a beef tapeworm (diphyllobothrium latum or taenia saginata)

characteristics: few or no symptoms, sometimes anemia

153

cysticercosis

infection from a pork tapeworm (taenia solium)

characteristics: variable symptoms depending on location and number of eggs that form larval cysts in the body

154

african sleeping sickness

infection of trypanosomes from the tsetse fly (arthropod)

characteristics: sleepiness, headache, coma

155

malaria

infection of plasmodium species from a mosquito (arthropod)

characteristics: chills, bouts of recurring fever

156

lyme disease

infection of borrelia burgdorferi from a tick (arthropod). known as the number one vector dsease

characteristics: fever, rash, joint pain, nervous system impairment