Microbiology I Flashcards
1
Q
What is microbiology?
A
The study of microorganisms:
- bacteria,
- protozoal parasites,
- viruses
- fungi.
These organisms can only be seen under the
microscope.
2
Q
What is the difference between prokaryotes and eukaryotes?
A
Prokaryotic cells:
- do not contain a membrane-bound nucleus
- generally smaller
- less complicated
- lack membrane-bound organelles
3
Q
What type of cells are prokaryotic?
A
- bacteria
- archaea
4
Q
What are the main steps in bacteriology?
A
- Clinical sample
- Pure culture
- Determination of antimicrobial resistance in bacteria
5
Q
State the percentages of Kingdoms on Earth.
A
78% bacteria
7.4% fungi
7.3% protists
7.3% animals
0.02% plants
6
Q
How is microbiology divided?
A
A. organisms studied
B. health related
C. processes, functions
7
Q
How is microbiology divided based on the organismsm studied?
A
- Bacteriology – study of bacteria
- Mycology – study of fungi
- Protozoology – study of protozoa
- Virology - study of viruses
- Parasitology – study of parasites
8
Q
How is microbiology divided based on its relation to health?
A
1.Etiology – identification of causative agent of disease
2.Epidemiology – study of spread, of disease
3.Immunology – study of immune system
4.Chemotherapy – treatment of disease with chemical compounds
5.Infection control – control of spread of infectious disease
9
Q
How is microbiology divided based on processes and functions?
A
- Microbial metabolism
- Microbial genetics
- Microbial ecology
10
Q
What type of cells are bacteria?
A
- simple
- single cell
11
Q
What type of cells are fungi?
A
- simple and multi-cell forms
eg. yeasts, filamentous molds, complex fungi
12
Q
What type of cells are protists?
A
- single cell or multi cell
- eg. algae, protozans, slime molds
13
Q
What type of cells are viruses?
A
- acellular
- intracellular parasites
14
Q
What type of cells are worms?
A
- multicellular
- more complex
15
Q
How are organisms named? In what form?
A
Binomial nomenclature:
- two-term naming system
- Carl Linnaeus
eg. Staphylococcus (genus) aureus (species)
16
Q
What does “Koch’s Postulate” inform us about?
A
the procedure for defining the agent of any disease.
17
Q
What are the 4 steps of Koch’s postulates?
A
- isolate the pathogen from the sick creature.
- grow the pathogen in the laboratory to obtain a pure culture.
- inoculate a healthy creature with a sample from the pure culture. The pathogen should cause the same disease symptoms as seen in the first creature.
- reisolate the same pathogen from the second sick animal.
18
Q
What are the two basic cell types of all living cells?
A
A. Eukaryotic (“true nucleus”) - more complex
B. Prokaryotic (“pre-nucleus”) - simpler, smaller
19
Q
What properties is the system of classification based on?
A
a. Type of cell - eukaryotic, prokaryotic
b. Structure - multicellular or unicellular
c. Mode of nutrition / metabolism - ingestion,
absorption, photosynthesis
d. Structure DNA.
20
Q
What do eukaryotic cells include?
A
Possess a true “nucleus”.
- Nuclear material surrounded by a nuclear membrane.
- Nuclear material organized into paired chromosomes.
- Nuclear membrane (DNA) associated with proteins called histones - form the chromosomes.
- Nucleus contains nucleolus - sites of ribosome synthesis.
Internal structure more complex - contains organelles - each have a specific function.
- Cytoplasmic streaming - continuous movement of the cytoplasm.
- Cell membranes contain complex lipids - sterols (cholesterol).
- Cell walls
- Occur only on plant cells, fungi
- Composed of cellulose, chitin.
- Division occurs by mitosis, meiosis.
21
Q
Describe the fungi kingdom.
A
- Eukaryotic, unicellular and multicellular, absorptive.
- Yeast, filamentous molds, complex fungi.
- Protista
- Eukaryotic, unicellular (few multicellular) , absorptive, ingestive, photosynthetic.
- Algae, protozoa, slime molds.
22
Q
Explain the general features of a prokaryote.
A
- Prokaryotic,
- unicellular,
- absorptive.
23
Q
What are the different types of bacteria?
A
1 ) Eubacteria - “true” bacteria
2) Archaebacteria – “ancient” (primitive) bacteria
a) Extreme acidophiles
b) Extreme thermophiles
c) Extreme halophiles
d) Methanogens
24
Q
What part of nomenclature are “Viruses”?
A
kingdom
25
What are the main differences between prokaryotes?
-morphology (size, shape, staining
characteristics)
-metabolic characteristics
-antigenic characteristics
-genetic characteristics
26
What is taxonomy?
The practice and science of orderely clasiffication of organisms into
hierarchical units tremed taxa (singular taxon).
27
What are the three interrelated parts to taxonomy?
- identification,
- nomenclature,
- classification.
28
What are most organisms grouped according to?
- genotypic characteristics
- phenotypic characteristics
29
What type of characteristics are the following?
DNA profiling, DNA-DNA hybridization, multilocus sequence typing (MLST) and percentage of guanine plus cytosine in an organism‘s DNA (GC ratio).
genotypic characteristics
30
What type of characteristics are the following?
morphology, metabolism, physiology, cell chemistry (particularly fatty acid composition in the case of bacteria) and motility.
phenotypic characteristics
31
What is the name of the ranking system of biological organisms?
Linnaean Classification
32
State the order of the 8 major taxonomic ranks.
1. domain,
2. kingdom,
3. phylum (plural, phyla),
4. class,
5. order,
6. family,
7. genus (plural, genera),
8. species.
33
What 5 kingdoms exist?
- animals,
- plants,
- fungi,
- protists
- bacteria.
34
What are the three domains?
1. Bacteria (microbial and prokaryotic)
2. Archae (microbial and prokaryotic)
3. Eukarya (eukaryotic)
35
Specify which is the generic name and species name of:
Bacillus anthracis
Bacillus = generic
anthracis = species
36
Which taxonomic rank is always capitalized?
Genus (generic name)
37
How are bacteria classified according to morphology?
1. SHAPE:
- coccus (spherical)
- bacillus (rod-shaped): short and plump
- spiral (helical or curved): spring-like
2. ARRANGEMENT
3. SPECIALIZED STRUCTURES
- flagella
- fimbriae, pilli
- capsules
38
How are bacteria classified according to the staining method?
gram positive or gram negative
39
State the main visual differences between gram positive and gram negative bacteria.
**1. Color After Gram Staining** + -
**+** purple/dark blue
**-** pink/red
**2. Cell Wall Thickness**
**+** thick peptidoglycan layer (20–80 nm)
**-** thin peptidoglycan layer (2–7 nm), located between two membranes
**3. Outer Membrane Presence**
**+** no outer membrane
**-** outer membrane present with lipopolysaccharides (LPS), making them more resistant to antibiotics
**4. Periplasmic Space**
**+** minimal or absent
**-** large periplasmic space between the membranes
**5. Teichoic Acids (Wall Polymers)**
**+** present (help in structural integrity and antigenicity)
**-** absent
**6. Resistance to Antibiotics and Disinfectants**
**+** more susceptible to antibiotics like penicillin due to exposed peptidoglycan
**-** more resistant due to the protective outer membrane
40
How are bacteria classified according to cultural characteristics?
**Colony Morphology** –
- shape,
- size,
- color,
- texture,
- margin of bacterial colonies on solid media (e.g., smooth, rough, mucoid).
**Nutrient Requirements **–
- growth on selective, differential, or enriched media (e.g., blood agar for Streptococcus).
**Oxygen Requirement **–
- obligate aerobes (require oxygen, e.g., Mycobacterium tuberculosis)
- obligate anaerobes (cannot tolerate oxygen, e.g., Clostridium botulinum)
- facultative anaerobes (can grow with or without oxygen, e.g., Escherichia coli)
**Pigment Production** –
- some bacteria produce colored pigments (e.g., Pseudomonas aeruginosa produces blue-green pigment).
**Hemolysis on Blood Agar** –
- Beta-hemolysis (complete lysis, e.g., Streptococcus pyogenes)
- Alpha-hemolysis (partial lysis, e.g., Streptococcus pneumoniae)
- Gamma-hemolysis (no lysis, e.g., Enterococcus faecalis)
**Growth in Liquid Media** –
- Turbid (cloudy) growth (e.g., E. coli)
- Pellicle formation (surface growth, e.g., Mycobacterium)
- Sediment formation (bottom growth, e.g., Clostridium)
41
How are bacteria classified according to bacteria motility?
**MOTILE BACTERIA **– Can move using flagella or other mechanisms.
**Monotrichous** – Single flagellum (e.g., Vibrio cholerae)
**Lophotrichous** – Tuft of flagella at one end (e.g., Helicobacter pylori)
**Amphitrichous** – One or more flagella at both ends (e.g., Spirillum)
**Peritrichous** – Flagella all over the surface (e.g., Escherichia coli)
Axial Filaments – Used by spirochetes for corkscrew-like movement (e.g., Treponema pallidum)
Gliding Motility – Movement without flagella, using surface proteins (e.g., Myxobacteria)
**NON-MOTILE BACTERIA**– Lack movement structures and rely on passive transport (e.g., Klebsiella pneumoniae).
- **atrichous**
42
How are bacteria classified according to enzymatic properties?
eg. ability to break down various carbohydrates
red- control
yellow- broken carbohydrate mannitol
43
How are bacteria classified according to the production of endospores?
**SPORE FORMING BACTERIA **– Can produce highly resistant endospores to survive harsh conditions.
- **Genus Bacillus** – Aerobic or facultative anaerobes (e.g., Bacillus anthracis)
- **Genus Clostridium** – Obligate anaerobes (e.g., Clostridium botulinum)
**NON-SPORE FORMING BACTERIA** – Do not produce endospores and are less resistant to extreme environments (e.g., Escherichia coli, Staphylococcus aureus).
44
What are the possible spore locations?
**Central Spores** – Form in the middle of the cell.
Example: Bacillus anthracis
**Subterminal Spores** – Form near the end but not at the very tip.
Example: Bacillus subtilis
**Terminal Spores** – Form at the very end of the cell.
Example: Clostridium tetani (gives a "drumstick" appearance)
45
How are bacteria classified according to the respiration type?
**Obligate Aerobes** – Require oxygen for survival and energy production.
Example: Mycobacterium tuberculosis
**Obligate Anaerobes**– Cannot survive in the presence of oxygen.
Example: Clostridium botulinum
**Facultative Anaerobes** – Can use oxygen when available but can also grow anaerobically.
Example: Escherichia coli
**Aerotolerant Anaerobes** – Do not use oxygen but can tolerate it.
Example: Streptococcus pyogenes
**Microaerophiles** – Require a low oxygen concentration (less than atmospheric levels).
Example: Helicobacter pylori
46
Compare the size of an eukaryote an prokaryote.
E: >5 μm
P: 0,5-3 μm
47
Compare the nuclear structure of an eukaryote an prokaryote.
E: nucleus-classic membrane, strands of DNA, diploid genome
P: no membtane nucleus, single circular DNA, haploid genome
48
Compare the cytoplasmic structures of an eukaryote an prokaryote.
E: mitochondria, golgi bodies, ER, ribosomes 80s (60+40), cytoplasmic membrane with sterols
P: ribosomes 70s (50+30), cytoplasmic membrane without sterols
49
Compare the cell wall of an eukaryote an prokaryote.
E: composed of chitin
P: complex structure (protein, and peptidoglycans, mureins)
50
Compare the reproduction of an eukaryote an prokaryote.
E: sexual and asexual
P: asexual (binary fission)
51
Compare the movement of an eukaryote an prokaryote.
E: complex flagellum
P: simple flagellum
| (only movement if flagellum is present)
52
Compare the respiration location of an eukaryote an prokaryote.
E: via mitochondria
P: via cytoplasmic membrane
53
What is the smallest bacteria type?
Chlamydia and Rickettsia (0.1-0.2
micrometer)
54
What are bacterial cell structures? State examples.
**Appendages** - flagella, pili or fimbriae
**Surface layers **- capsule, cell wall, cell membrane
**Cytoplasm** - nuclear material, ribosome, mesosome,
inclusions etc.
**Special structure** – endospore.
55
What species has most evident motility? How is this seen?
- spreads across Petri Dish
- proteus species most evident
56
What is the arrangement basis of the flagellum for classification?
* **Monotrichous**; 1 flagellum (a)
* **Lophotrichous**; tuft at one end (d)
* **Amphitrichous**; both ends (b)
* **Peritrichous**; all around bacteria (e)
57
What bacterias do not classify for gram staining? Why?
- **Mycobacteria** (waxy outer shell , distinguished by acid fast stain)
- **Mycoplasmas** (no peptidoglycan)
58
What is the order of chemicals used for gram staining?
1. crystal violet
2. iodine (mordant)
3. alcohol (decolorisation)
4. safranin (counterstain)
59
State the factors influencing a gram positive cell wall.
Peptidoglycan + (60-90 persent)
Teichoic acid (important virulance factors)
Lipoteichoic acid
Complex polisaccarides (C polysaccharides)
M protein of streptococci
R protein of staphylococci
60
What is the main difference between the gram +'ve and -'ve cell cell wall?
+'ve: thick cell wall with peptidoglycan, no outer membrane
-'ve: thin cell wall with little peptidoglycan, has outer membrane
61
State the composition of the bacterial capsule.
- large structure common to many bacteria.
- polysaccharide layer
- lies outside the cell envelope
- part of the outer envelope of a bacterial cell.
- most= polysaccharide,
- some= poly-D-glutamic acid (Bacillus anthracis)
62
Where is the capsule most commonly found?
gram negative bacteria
eg.
* Escherichia coli (in some strains)
* Klebsiella pneumoniae
* Pseudomonas aeruginosa
* Salmonella typhi
* Acinetobacter baumannii
63
Which Streptococcus produces a capsule?
Streptococcus pneumoniae
64
State the importance of spores.
- small
- oval or spherical structures
- very resistant to high temperatures, radiation, desiccation, and chemical agents.
- endospore=formed intracellularly
- vegetative cell= bacterial cell producing spore
- resistant to harsh conditions (loss of nutritional requirement)
- produce some gram-positive bacteria
- never gram-negative bacteria
- spore produces two genera: Bacillus, Clostridium
eg. Bacillus cereus, Clostridium botulinum, Clostridium perfringens
65
What is a vegetative cell?
A bacterial cell which produces spores.
66
What is an endospore?
A spore which is formed intracellularly.
67
What type of bacteria produces spores?
some gram positive bacterias, never gram negative!
68
What genera produce spores?
Bacillus
Clostridium
69
Clostridium tetani and Clostridium botulinum produce endospores at what location?
Clostridium **te**tani: **te**rminal endospore ‘drumstick’
Su**b**terminal:
Clostridium **b**otulinum
70
What are the investigation methods of microbiology?
I. **Microscopic examination**: determination of the microorganism morphology in the clinical/pathological material (light and electron microscopy).
II. **Bacteriological investigation**:
isolation of pure culture from clinical/pathological material determination of biological properties and antimicrobial susceptibility.
III. **Immunologica/serological investigation**:
detection of antibodies, agent in test substance by immunoassay
IV. **Genetic investigation**:
DNA-DNA or DNA-RNA hybridization (detection of pathogen genes in test substance).
V. **Biological investigation**
laboratory animals are infected with the material artificially induced by the infectious process and isolate and identify the disease-causing microorganisms.
