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1
Q

TYPES OF MICROBIOLOGY:

A

Theoretical or Pure Microbiology Practical

Applied Microbiology

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2
Q

THEORETICAL(PURE) MICROBIOLOGY:

A

Study of occurrence, Form , Structure Classification, Physiology, Reproduction, Heredity, Variation & Evolution of microbes

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3
Q

APPLIED MICROBIOLOGY:

A

Exploitation of beneficial microbes; Control the activities of harmful microbes

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4
Q

types of applied microbiology

A

Medical Microbiology

Agricultural & Veterinary Microbiology

Food Microbiology

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5
Q

kochs postulate and the postulates

A

Koch’s Postulates: a sequence of experimental steps that verified the germ theory.
a. The causative (etiologic) agent is isolated from a sick individual. This agent is absent in healthy individuals.
b. The agent is cultured, grown outside the host.
c. When the cultured etiologic agent is introduced into a healthy individual, it becomes sick.
d. The etiologic agent is cultured from the experimental sick organism.
Nowadays, a 5th is added - specific antibody to the bacterium should be detectable in the serum during the course of the disease.

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6
Q

Exceptions to Koch’s postulates

A
  1. Microbes that cann’t be grown on artificial media
    e.g: Viruses, Rickettsia, Treponema
  2. More than one microbe produces the same disease
    e.g: Pneumonia, meningitis
  3. One microbe that causes multiple diseases
    e.g: S. pyogenes – sore throat, Scarlet fever
  4. Strictly human diseases with no animal model
    e.g: Rubella, small pox
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7
Q

classification of bacteria based on the characteristics of their cell wall is called

A

bergeys classification

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8
Q

Bergey’s classification Bacteria are divided in to 4 divisions (phyla)

A

Division I. Gram negative bacteria
Spirocetes, Rickettsia, Chlamydiae, Aerobic, Facultatve anaerobic & Anaerobic bacteria

Division II. Gram positive bacteria
Cocci: Non-spore forming
Spore forming Rods
Regular & irregular non-spore forming rods: Lactobacillus, Corynebacteria,
Mycobacteria, Nocardia, Actinomyces

Division III. Wall-less bacteria: Mycoplasma

Division IV. Archaea

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9
Q

all organisms are grouped into 1 of 3 categories or domains based onribosomal RNA(rRNA) sequences

A

Bacteria,Archaea, & Eukarya

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10
Q

prokaryotes

A

Bacteria: Eubacteria, Archaebacteria
Blue-green algae (cyanobacteria)

characteristic
Prokaryotes lack histones but eukaryotes have
Procaryotes are not compartmentalized
Cell membranes lack sterols
Ribosomes – 70S with subunits 30S & 50S

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11
Q

eukaryotes

A

Algae (except blue-green): Eg. Diatoms,
Protozoa (Parasites, E.g. Plasmodium, Amoeba)
Fungi: yeasts
Slime molds

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12
Q

archae

A

mostly unicellular, cells lack a nucleus or any other organelle, they have 70S ribosomes, and allArchaeaare microbes.

But different cell walls that is composition (lack peptidoglycan and might have pseudomurien instead).

rRNA sequences have shown that they are not closely related toBacteriaat all.

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13
Q

difference

A

Chromosome Number
Multiple, linear Single, circular

Nuclear membrane
Present Absent

Nucleus
True Nuclear material

Sexual reproduction
Present Absent (binary fission)

Ribosomes
80S 70s (30 & 50s)

Organelles*
Present Absent

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14
Q

The word bacteria

A

The word bacteria - derived from the Greek word ‘bakterion’ to mean little rod.

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15
Q

bacteria

A

Bacteria are microscopic organisms whose single cell have neither a membrane-enclosed nucleus nor other membrane-enclosed organelles like mitochondria, chloroplasts, etc.

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16
Q

The 2 bacterial kingdoms

A

Archaebacteria: without muramic acid, live in very harsh or extremely salty environments
Eubacteria (Bacteria & Cyanobacteria)

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17
Q

eubacteria

A

true bacteria

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18
Q

nomeclature

A

generic then species

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19
Q

Size of bacteria

A

Bacteria range from 0.2-2.0m in diameter & 2-8μm in length

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20
Q

Shape of bacteria

A

The 3 major morphological types/ basic forms:
Coccus (Cocci): Spherical
Bacillus (Bacilli): Rod-shaped, cylindrical
Spiral (Helical): Subtypes - spirillium, spirochaetes
Other intermediate shapes: coccobacilli, fusiform, etc

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21
Q

Arrangements of cells
Depend on the plane of successive cell divisions.
of cocci

A

Micrococcus: Single
Diplococcus: Duplicate
Streptococcus: Chain
Staphylococcus: Cluster of grape
Tetrads: Packets of 4
Sarcinae: cubical packets of 8

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22
Q

Arrangements of cells
Depend on the plane of successive cell divisions.
of bacilli

A
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23
Q

A bacterial cell consists of the following structures:

A

External structures (appendages)
cell envelope
Internal organs
others

24
Q

External structures (appendages)

A

Flagellum - Rapid motility, chemotaxis, sensing
Pilus (pili) - Adhesion, sex. Fimbriae
Capsule – Resists phagocytosis

25
Q

Cell envelope:

A

Cell wall: Useful to maintain the shape/rigidity of the bacteria
Cytoplasmic membrane – Selective permeability

26
Q

internal organs

A

Cytoplasm: the following are found in the cytoplasm
Nucleoid (nuclear material)
Mesosome (Cell division)
Ribosome (Protein synthesis)

27
Q

Other – structural changes

A

endospore

28
Q

Flagellar Antigens

A

H Antigens

29
Q

Flagella have 3 basic parts:

A

1.Filament: Outermost region.
Contains globular protein flagellin.
Not covered by a sheath like eucaryotic filaments.

  1. Hook: Wider segment that anchors filament to basal body
  2. Basal Body: Complex structure with a central rod surrounded by a set of rings
30
Q

Types /arrangements of flagella:-

A

Monotrichous - Single polar flagellum

Lophotrichous - 2 or more at 1 end (tuft at one end) s, a tuft of flagella at one end

Amphitrichous - Tufts at both polar ends, one or more flagella at each end

Peritrichous - Flagella all over the surface; Distributed around the cell, E.g – Enterobacteria

31
Q

Axial Filaments (Endoflagella)

A

Periplasmic flagella also called axial filament are found in Spirochetes: T. pallidum, Borrelia burgdorferi.

Rotation of endoflagella produces a corkscrew motion

32
Q

Functions of pili:

A

1.Adhesion to cells. Used for attachment rather than motility
Category according to functional activities:
Adhesins
Lectins
Evasins
Sex pili

  1. F-pilus; used in conjugation. Genetic transfer (sex pili)
  2. Flotation; increase boyancy
33
Q

Slime Layer

A

Thin polysaccharide substance that is loosely attached to the cell wall. Important for virulence

34
Q

Capsule

A

Gelatinous Polysaccharide substance (except in B. anthracis, which is polypeptide) that is firmly attached to the cell wall

35
Q

Capsulated strains form

A

mucoid or smooth (S) colonies.

36
Q

Capsule stain. The capsule stain is an example of a …………… staining technique. The bacterial cells and the background stain, but the capsules do not.

A

negative

37
Q

Function of capsule

A

Protects cells from drying out

Adhere bacteria to surface
S. mutans and enamel of teeth

Prevents phagocytosis
Important for virulence by protecting from phagocytosis
Complement can’t penetrate sugars

38
Q

Diagnosis of capsules

A

India ink/Negative stain: Welch method
Quellung reaction (Capsular swelling):

39
Q

Teichoic acid has the following actions:

A

Sequester / bind cations, e.g Mg2+
Serve as attachment site for bacteriophages
Serves as source of major surface Ags

40
Q

M - proteins –

A

Found in Group A Streptococcus (S. pyogenes)
Helps in adherence / colonization of the bacteria
Prevents the cell from antibiotics or other harmful substances

41
Q

Components of Gram positive bacterial cell wall

A

Peptidoglycan – thicker

Polysaccharides - (50 - 80%)

Teichoic (or teichuronic) acid - techoic has phosphate

42
Q

Components of Gram negative cell wall

A

Lipoprotein: mediates the attachment of OM to PG

outer membrane: A phospholipid-protein bilayer membrane

Peptidoglycan:- (2-10%)

Lipopolysaccharide (LPS) – Contains 3 parts -
a. O-specific chain (somatic Ag), a repeating unit: highly spp specific, contain antigenic determinant
b. Core polysaccharide: has KDO (2-ketone-3-deoxyoctanoic acid) and amino sugars.
c. Lipid A (toxic, endotoxin) made up of long chain fatty acids.

43
Q

Bacteria with defective cell wall

A
  1. Mycoplasma:- Independently existing genus.
  2. L - Forms:- Produced in the lab or by penicillin treatment in the body; can replicate in ordinary media; more stable then the next
  3. Spheroplasts:- Obtained from Gram negative cells, retain some residue but non functional cell wall; osmotically fragile, produced artificially by lysozyme or by growth with penicillin or any other agent
  4. Protoplasts:- Obtained from Gram positive cells; may be produced artificially by lysozyme and hypertonic medium (osmotically fragile)
44
Q

Function of bacterial cell membrane

A

Selective permeability & transport of solutes into the cell

Electron transport & oxidative phosphorylation.

Site of enzyme & carrier molecules: macromolecular synthesis – cell wall synthesis

Excretion of hydrolytic exoenzymes

45
Q

Mesosomes are

A

Mesosomes are convoluted invaginations of cytoplasmic membranes often at sites of septum formation.
are common in Gram-positive bacteria. bc no om

46
Q

Types 3 ans 2 Vesicular, lamellar, tubular

A

Vesicular, lamellar, tubular

septal lateral

47
Q

Bacterial spores

A

Bacterial spores are dormant forms of bacteria which are thick walled, highly refractile and resistant.

48
Q

When the supply of ………. is limited, certain bacteria develop endospores

A

C, N & P

49
Q

Endospores exhibit no signs of life, being described as

A

cryptobiotic

50
Q

The heat resistance of spores is due to their

A

dehydrated state & presence of large amount of calcium dipicolinate

51
Q

Spores may be located as:

A

Central (e.g Clostridium perfringens, C. botulinum, Bacillus anthracis)
Terminal (e.g. C. tetani)
Sub-terminal (C. speticum, C. welchii, C. sporogenes)

52
Q

Clostridal spores – bulged or not bulged; Bacillus spore – bulged or not bulged

A
53
Q

Structure of Endospore

A

Core: spore protoplast. Contain complete nuclear material, protein synthesizing apparatus
Spore wall: innermost layer surrounding the inner spore membrane. It contains normal peptidoglycan and becomes the cell wall of germinating vegetative cell
Cortex: the thickest layer of the spore envelope. Cortex peptidoglycan is susceptible to lysozyme
Coats (outer & inner): Composed of keratin like protein
Exosporium: Lipoprotein membrane containing carbohydrates

54
Q

All spore-forming bacteria are Gram ………. and spore formation depends on the ability to develop thick wall.
Spore formation is confined largely to ……………

A

positive

bacilli & few cocci.

55
Q

Exospores (conidia)

A

They are not resistant to heat and disinfectants.
Exospores, like endospores are cryptobiotic

actin and fungi

56
Q

There are 2 different enzymes that break down H2O2:

A

Catalase: Breaks hydrogen peroxide into water and O2.
Produced by humans, as well as many bacteria
Peroxidase: Converts hydrogen peroxide into water.

Micro (7 decks)

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