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Bacteriology Flashcards

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1
Q

Who introduced the term microbiology and what did he demonstrate and in what year

A

French Chemist, Louis Pasteur who demonstrated that fermentation was caused by growth of bacteria and yeasts (1857-60).

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2
Q

Who started the controversy of origin of microorganisms and what was their theory

A

Louis Joblot (1718) and John Needham (1749)-

Spontaneous generation.

LJ and JN

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3
Q

Who settled the controversy of origin of microorganisms and what was their theory

A

Lazzaro Spallanzani (1765 and 1776) and Louis Pasteur (1860-64) settled the controversy with the specific conditions required for sterility (115-120oC).

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4
Q

Who first saw microorganisms and in what year and what did he call them

A

Anthony van Leuwenhoek
animalcules
1675

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5
Q

Who discovered heat resistance spores

A

Ferdinand Cohn (1876) discovered heat resistant spores.

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6
Q

Who developed a method for isolation of pure cultures from mixed cultures on nutrient agar in dried film stained with aniline dyes

A

Robert Koch in 1877

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7
Q

Baxter are prokaryotes true/false

A

True

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8
Q

What is the size of bacteria and give an example of the largest bacteria

A

0.5 mm- 0.5 µm

>0.5 mm is Thiomargarita namibiensis and Epulopiscium fishelsoni

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9
Q

How many bacteria are on earth

A

5 x 10^30

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10
Q

What are mycoplasmas and eg

A

Prokaryotes that differ from true bacteria in their smaller size and their lack of rigid cell wall

E.g. M. genitalium, M. pneumoniae, M. pulmoni

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11
Q

What leads to extreme pleomorphism and sensitivity to external osmotic pressure in mycoplasma

A

Lack of rigid cell wall

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12
Q

What is the diameter of mycoplasma and what is he advantage of their diameter

A

Diameter of 0.15-1 μm

capable of passing through filters that retain bacteria

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13
Q

Where are mycoplasma cultivated

A

Cell free nutrient media

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14
Q

Which organisms are Smallest and simplest organisms capable of autonomous growth

A

Mycoplasma

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15
Q

What are Rickettsiae and where do they grow

A

Ricketsia are rod-shaped, spherical or pleomophic Gram-negative organisms
●Smaller than true bacteria but are observable in light microscope
●Mostly grow only in living tissues e.g Rickettsia prowazekii

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16
Q

What are chlamydiae

A

Chlamydiae are similar to reckettsiae but have a more complex intracellular cycle e.g. Chlamydia trachomatis

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17
Q

What is the function of flagella, sex pilus and common pily( fimbriae) and what is the predominant chemical composition present in all

A

Flagella-Swimming movement

Sex pili-Stabilizes mating bacteria during DNA transfer by conjugation

Common pili-Attachment to surfaces; protection against phagotrophic engulfment

Protein is the predominant chemical composition present

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18
Q

What is the function of capsule in bacteria and what is the predominant chemical composition present

A

Attachment to surfaces; protection against phagocytic engulfment, occasionally killing or digestion; reserve of nutrients or protection against desiccation

Polysaccharide and occasionally polypeptides

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19
Q

Function of plasma membrane and chemical composition

A

Permeability barrier; transport of solutes; energy generation; location of numerous enzyme systems

Phospholipids and proteins

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20
Q

Function of Gram positive cell wall and gram negative cell wall and their chemical composition

A

Gram-positive bacteria
Prevents osmotic lysis of cell protoplast and confers rigidity and shape on cells

Chemical composition-Peptidoglycan (murein) complexed with teichoic acids

Gram-negative bacteria
Peptidoglycan prevents osmotic lysis and confers rigidity and shape; outer membrane is permeability barrier; associated LPS and proteins have various functions

Chemical composition
Peptidoglycan (murein) surrounded by phospholipid protein-lipopolysaccharide “outer membrane”

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21
Q

Function of ribosome and chemical composition

A

Sites of translation (protein synthesis)

RNA and protein

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22
Q

Function of inclusions in bacteria and chemical composition

A

Often reserves of nutrients; additional specialized functions

Chemical composition
Highly variable; carbohydrate, lipid, protein or inorganic

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23
Q

Function of chromosome and Plasmid and their chemical composition

A

Chromosome-Genetic material of cell
Composition -DNA

Plasmid-Extrachromosomal genetic material

Composition -DNA

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24
Q

What is peotidoglycan or murein or mucopeptide made of

A

made of amino sugars N-acetyl glucosamine and N-acetyl muramic acid.
The bases are in an extensive cross-linking between neighbouring peptide chains.

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25
Q

What is Gram +ve wall made of

A

Peptidoglycan
Techoid acid
Polysaccharides

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26
Q

Peptidoglycan make up 50 – 90% of Gram-positive wall and how many in Gram-negatives ,

A

5-10%

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27
Q

What are techoid acids and their functions

A

polymeric complexes of ribitol phosphate or glycerol phosphate

Functions
bind and regulate movement of cations into and out of the cell

●prevent extensive wall breakdown and possible cell lysis during cell growth

●provide much of the cell wall’s antigenicity

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28
Q

Under what condition will protoplasm of bacteria remain intact and not undergo lysis

A

Can only be maintained in intact form in hypertonic solutions.

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29
Q

Which type of cell wall has more lipids and proteins but is less complex

A

Gram +ve

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30
Q

Where are the hydrophilic and hydrophilic ends of the cell membrane

A

Hydrophilic is inside

Hydrophobic is outside

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31
Q

what may facilitake rapid transfer of mRNA from the nucleus to the ribosomes.

A

nucleus

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32
Q

what is flagella and what do they do

A

long, thin (about 20 nm), whip like appendages

Locomotor organs of bacteria

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33
Q

what protein does flagella have and can it move when the cell wal is absent

A

flagellin

no it cant

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34
Q

what is characteristic about protoplast obtained from Baccillus species

A

they have normal flagella which cant move

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35
Q

give the four types of flagella an example of species

A

monotricous- Vibro cholera
lophotrichous- Bartonella bacilliforms
amphitricous- spirillum serpans
Peritricous- E,coli

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36
Q

what is the order of flagellum self assemble

A

page 38

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37
Q

what protein is in fimbrae or pilli

A

pilin

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38
Q

which bacteria are fimbrae\pilli found

A

gram negative bact

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39
Q

how do fimbrae/pilli differ from flagella

A

they play no role in locomotion

shotter thinner straigter

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40
Q

what is the use of sex pili in CERTAIN BACTERIA

A

forms congugation tubes

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41
Q

which genus of bacteria produce spores

A

Bacillus, anthrax and Clostridium

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42
Q

where are spores situated in bacteria

A

EQUATORIAL-middle
SUBTERMINAL-near end
TERMINAL-at the ends

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43
Q

what is spore feild

A

Spore field is destined to be the site of formation of the new spore

44
Q

spores arem dormant forms and they dont metabolise and reproduce T OR F

A

TRUE

45
Q

Describe the stages of spore formation

A
  • the chromatin condenses in SPORE FEILD
  • chromatin is divided by septum of plasma membrane to form the SPORANGIUM and FORESPORE
  • thesporangium engulfs the forespore and 2 layers(outer and inner) form
  • inner layer becomes spore coat and outer layer EXOSPORIUM
  • cortex is formed in betwwen the spore coat and exosporium
  • bacteria raptures and spore is released
46
Q

what is the cortex found in endospores made of

A

calcium and dipicolinic acid

47
Q

what 4 things are spores resistant to that even the vegetative forms are susceptible

A
  • heat,
  • ultra-violet irradiation
  • mechanical disruption
  • most chemical disinfectants
48
Q

what three things differ spores from vegetative forms

A

chemical composition, antigenic structures and morphology

49
Q

the cortex has low density

the cortex has high affinity for dyes
t/f

it contains most of the mucopeptide of spore

A

true

false

true

50
Q

what amino acids are spores rich in and what do these amino acids do

A

sulpher containing amino acids-eg CESTEINE

the disulphide linkages in cestein are responsible for increased radiation resistance

51
Q

what is responsible for heat resistance in spore

A

calcium dipicolinic acid chelate in exosporium

52
Q

what trigger and conditions initiate sporulation

A

condition
nutrient limitation,by unnatural means, e.g.
by mechanical abrasion or
by exposure to certain surface active compounds.

trigger nutrients
usually simple sugars, amino acids and ribosides present in the environment

53
Q

are capsule essential to life of cell?

A

no, since it can be lost spontaneously by mutation

54
Q

what component ofPATHOGENIC bacteria is viscous polysaccharide gums which give the colony of the organism a mucoid appearancE

A

CAPSULE

55
Q

WHAT DYES do capsules have low afinity to and what type os staining procedures are capsules demonstrated

A

aniline dyes

negative staining procedures

56
Q

what is the function of the forespore and sporangium

A

sporangium produces nutriets for the vegetative cell

forespore produces nutrients(proteins) for spore

57
Q

how many layers surround the genetic material of spore

A 
4
inner layer- spore wall
cortex
spore coat
 exosporium
58
Q

what are metachromatic or volutin granules

A

granules in many species of bacteria which stains basic dyes intensively

59
Q

what is unusual about the capsules of BACILLUS genus

A

they have large polypeptides instead of the usual normal polysaccharide

60
Q

what will make a bacteria avirulent

A

when it loses capsule bu enzyme or mutaion

virulence is being resistant to pathogens

61
Q

what volutin or metachromatic granule is typical of CORYNEBACTERIA

A

polyphosphate granule

62
Q

what will make volutin granules accumulate

A

when grown on rich media

63
Q

what are involution forms of volutin

A

irregular coarse spiral structures of granules

64
Q

when does binary fission occur and what are the steps

A

Occurs when cell reaches a critical size

first stage consists of a division of the nucleus
followed by division of the cell membrane and cell wall

65
Q

what is TRANSFORMATION repro in bacteria

A

Direct uptake and incorporation of exogenous genetic material from its surroundings through the cell membrane

eg of bacteria that undergo transformation-Streptococcus pneumoniae deficient in capsular material

Highly energy dependent process

66
Q

what is conjugation

A

Involves the active passage of genetic material from one cell to another by means of the sex pili
F+ strains transfer to F- strains

67
Q

if a transformation reproducing bacteria doesnt need a particular dna what does it do to it

A

it destroys it

68
Q

why are dna plasmid not incorporated into bacteria when transformation occurs

A

they can transcribe and translate(PROTEIN SYNTHESIS) on their own. if cell is undergoing transcription plasmid does same

69
Q

what is transduction

A

transfer of genetic material from Some temperate viruses, do not cause this catastrophic event when they infect their host

70
Q

what are bacteriophages

A

Viruses, called bacteriophages can attack bacteria.
The attack involves the injection of viral DNA into bacterial cells
They proceed to make new virus particles and destroy cells

71
Q

what are the three bacterial growth seen in lab

A

Development of colonies

Transformation of a clear broth medium to a turbid suspension

Biofilm formation

72
Q

what three factors inhibit bacterial growth

A

Exhaustion of nutrients

Accumulation of toxic metabolic end-products

Achievement of a maximum population density

73
Q

The time interval between one cell division and the next is called?

A

mean generation time

=time b etween divisions/ number of generations= t/y

74
Q

what is the formula for finding number of cells in a generation
what is the formula when the initial number for the first generation is unknown

A

y=number of generation
n=cell population

yth generation n= 2^y

when initial number is unknown= n, the cell population,n= n x 2^y
log n = log n* + y log 2
y = (log n – log n*) / log 2
log2= 0.301

meanGtime= t/y= 0.301t / (log n – log n*)

75
Q

What are he four main phases of bacterial growth

A

Lag phase- bacteria prepares for cell division at critical size

Exponential/Log phase - actual cell division occurs

Stationary- it only occurs when there is nutrient depletion

Death- when nutrients are finished

76
Q

What are micro capsule

Can they be seen under microscope

A

Surface antigens, which exist in a distinct layer external to the cell wall
●E.g. M antigens of the Streptococci and the Vi antigens of S. typhi

Insufficiently thick to be seen by ordinary microscopic methods

77
Q

Can cells start dividing in lag phase

A

Yes

78
Q

What are autotrophs and what do they feed on

A

Back which utilizes simple imorganic compounds(carbon and nitrogen from Co2 and ammonium salts)
They have HIGH SYNTHETIC POWER

79
Q

What are heterotrophs

A

They require ORGANIC sources of carbon

Carbohydrates, Amino Acids, Preoteins and Fatty acids

80
Q

What is a facultative organism

A

facultative can undergo aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent.

81
Q

Can Nitrate be utilized as an alternative source of nitrogen by some of the heterotrophic bacteria and if yes how

A

Yes

It has the enzyme nitratase- Nitratase reduces nitrates to ammonia

82
Q

What are the three major growth factors

A

Amino acids

Vitamins

Miscellaneous groups eg nitrogenous bases

83
Q

What are non exacting and highly exacting bacteria with egs

A

Non exacting uses a single amino acid for its growth
Eg: S. typhi (single amino acid, tryptophane)

Highly exacting uses a lot of amino acid(this may be because they are aromatic types and diffficult to synthesize)
Eg: Leuconostoc mesenteroides, which requires 17 amino acids (not self synthesize)

84
Q

Between gram positive and negative which is more exacting

A

Gram positive

85
Q

What is the use of lipoid acid vitamin

A

Oxidative decarboxylation of purification acid

86
Q

What is the use of haematin

A

Part of cytochrome and part of the enzymes PEROXIDASE and CATALASE

87
Q

What is the concentration of Co2 needed by bacteria for initiation of growth

A

Low concentration

88
Q

Which bacteria species need large amounts of Co2

A

Gonococci
Meningonococci
Brucella abortus

89
Q

What are obligatory aerobes and anaerobes

A

Obligatory aerobes, grow only in its presence of O2

Obligatory anaerobes grow only in absence of oxygen

90
Q

Why can’t ananaerobes thrive under O2

A

They don’t have enzymes catalase to break down H2O2 to O2

91
Q

What is the optimum temp for pathogenic bacteria and their limits

A

Pathogenic bacteria optimum growth temp is 37oC with upper (40 to 50oC) and lower growth limits (15 to 20oC)

92
Q

What temperatures do mesophiles, psychrophiles, and thermophiles need

A

Mesophiles: 20 - 45°C

Psychrophiles: less than then 10 - 20°C

●Thermophiles: 40 - 80°C >( or even more)
due high heat resistance of their enzymes

93
Q

What are neutrophils, acidophiles and alkaliphiles

A

●Neutralophiles or Neutrophiles: grow neutral pH 7.4 - 7.6

●Acidophiles :grow best at acidic pH < 5.5 eg: Acetobacter aceti

●Alkaliphiles: grow best at alkaline pH 8.5 – 11 eg: B. subtilis

94
Q

What are halophiles

A

tolerate high conc. of salt

●Moderate halophiles -marine bacteria (3% NaCl)

●Extreme halophiles grow well in salt concentrations in excess of 15%. Eg: Salinibacter ruber

95
Q

What are Osmotolerant bacteria, Osmophiles, Barotolerant and Barophiles

A

Osmotolerant bacteria: grow in high solute conc.

Osmophiles: grow best at high osmotic pressures

Barotolerant bacteria: grow at very high hydrostatic pressures

Barophiles: grow best at high hydrostatic pressures

96
Q

How does light kill bacteria and how do some bacteria protect themselves

A

formation of singlet oxygen (free radical) causes death of bacterial cells

Some produce pigments that protect them
●E.g. yellow, orange or red carotenoid pigments interfere with the formation and action of singlet oxygen

97
Q

Where are culture media prepared from and sources

A

Media prepared from protein by acid or enzymic digestion

sources
●Muscle tissue (meat),
●Casein (milk protein)
●Blood fibrin

98
Q

Why is Nacl added to culture media

A

To optimize the tonicity

99
Q

How can liquid media be solidified

A

may be solidified by a natural carbohydrate gelling agent, agar derived from seaweed.
(found in the cell wall of red algae, especially genus Gelidium. E.g. Palmaria polysiphonia)

100
Q

Who discovered gram staining

A

Discovered by a Danish Physician, Hans Christian Gram, in 1884

101
Q

What are the four steps of gram staining

A

Step 1: apply primary stain (crystal violet)

Step 2: apply mordant (iodine)

Step 3: apply decolourising agent (acetone/ethanol)

Step 4: apply counter/secondary/contrast stain (safranin)

102
Q

What are the basic building blocks of murein

A

NAG and N-Acetyl Muramic acid

103
Q

What is the function of the amino acids on the peptidoglycan

A

They link the peptidoglycan units together in horizontal and cross sectional bridges
Are peptide bonds

104
Q

What are the two types of technic acid

A

Wall and membrane(lipo) it hold the cell wall when the bacteria is dividing into two
Stability ,transport of certain items and have antigenic functions

105
Q

Why are gram negative said to be more complex

A

Gram negative have lps layer so are said to be biochemically complex

106
Q

What is protplast and spheroplast

A

Protoplasts is gram +ve that loses its cell wall artificially and
sphero is gram neg

107
Q

Ribosomes are in two forms, what are they and what is their sedimentation coefficient

A

he maker form has a sedimentation of 30s and the bigger form has 50 s
They combine to form 70 s

Microbiology (5 decks)

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