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Microbiology > 1st colloquium > Flashcards

1st colloquium Flashcards

1
Q

Definition of microbiology

A

It is the study of microorganisms, researches the ecology, morphology, physiology and genetics of them as well as their interaction with others.

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2
Q

Medical microbiology object, tasks and its connection with other fields of biology and medicine (3)

A

Researches:

  • organisms that are pathogenic to humans
  • commensal microbial flora of humans and it’s implication to diseases
  • develops the isolation and identification methods of medically important organisms
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3
Q

Origins of microbiology. Historical stages of microbiology development

A

Anton Van Leeuwenhoek

the 1st one to make lenses and observe microorganisms

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4
Q

Louis Pasteur, his works and their influence on medical microbiology development (4)

A
  • He came up with the food preparing known as pasteurization
  • Developed vaccination for anthrax and rabbies
  • His discoveries provided suppor for the germ thoery of disease and it’s application in medicine
  • He discovered the existence of life without oxygen. Bacteria can survive in anaerobic conditions.
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5
Q

Robert Koch, his works and their influence on medical microbiology development (3)

A
  • Founder of modern bacteriology
  • Developed a way of staining bacteria to improve it’s view under the microscope
  • identified the specific causative agents of tuberculosis
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6
Q

Classification and nomenclature principles of bacteria

-Criteria for classification (5)

A

Criteria for classification

  • Morphology
  • Staining properties
  • Physiology
  • Biochemical properties
  • Genotypic characteristics
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7
Q

Classification of bacteria

  • Taxonomic categories
  • Species criteria
A
  • group of bacteria which have certain characteristics of homogeneity (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species)
  • entire group of organisms with common origin and close genotype (degree of DNA homology is more than 60%)
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8
Q

Prokaryotes - characteristics (6)

A
  1. DNA is circular, free-floating in the cytoplasm
  2. No nucleus or membrane bound organelles
  3. Small (1-5um)
  4. Always unicellular
  5. Asexual
  6. Contain pili
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9
Q

Eukaryotes - characteristics (6)

A
  1. DNA is linear, found in nucleus
  2. It has membrane bound organelles
  3. Larger (10-100um)
  4. Can be unicellular or multicellular
  5. Sexual OR asexual
  6. Do not contain pili
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10
Q

Morphology and Arrangement of bacteria (3)

A

Spherical
Rod
Spiral

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11
Q

Spherical bacteria (5)

A 
Diplococci
Streptococci
Tetrad
Sarcinae
Staphylococci
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12
Q

Rod-shaped bacteria

A

According to length –> long (more than 3um), short (1.5-3um), very short (less than 1um)
According to their cell ends –> round, sharp, cutted, thickened, barrel
According to diameter –> thin (0.25-0.5um), thick (0.5-1.5um)

Arrangement –> single bacillus, diplobacilli, sterptobacilli, coccobacillius

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13
Q

Spiral bacteria

A

Vibrio
Spirillum
Spirochete

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14
Q

Dark-field microscope

A

A light source is present and after that condenser lens which condenses the beam of light into a point, over the specimen there are objective lens which will collect the rays. It can be used to observe light bacteria motion

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15
Q

Electron microscope

A

Uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of photons. These microscopes have a higher resolving power than light microscope.

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16
Q

Stereoscopic microscope

A

Uses light reflected from the surface of an object rather than transmitted through it. It uses two separate optical paths with 2 objectives and eyepices to provide a slightly different viewing angles to the left and right eyes. This produced a 3D visualization of the sample.

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17
Q

Phase-contrast microscope

A

It has two components –> annular ring (present in the condenser) and phase ring (present in the objective).
When light passes through the specimen, the phase shifts and there will be refraction in different directions.
When the refracted light hits the phase ring, the phase shift of light increases and that region will be dark. If it does not hit the ring, then that region will be seen light.

18
Q

Fluorescent microscope

A

Involves staining organisms with a special fluorescent dye and then examining them with a specially designed microscope

19
Q

Simple and complex staining methods

A

Simple –> uses a single dye. It shows only sizes, shapes, arrangements of the cell

Complex –> uses 2 or more dyes that react differently with various kinds or parts of bacteria, allowing them to be distinguished

20
Q

Gram staining method (4)

A
  1. Bacterial cells take up crystal violet
  2. Iodine is added
  3. Gram - bacteria cannot retain crystal violet, so they are decolorized by alcohol, losing the color of the primary stain
  4. After decolorization, a counterstain is used –> Safranin

Gram - –> stain red/pink due to the countertaining safranin
Gram + –> stain purple due to the retaining of the primary dye –> crystal violet

21
Q

Wirtz staining method (3)

A
  • Identified specialized structures.
  • Endospores retain malachite green stain and vegetative cells accept safranin counterstain and appear red
  • allows visualization of hard- to- stain bacterial endospores.
22
Q

Ziehl-neelsen staining method (3)

A
  • Distinguishes members of genera mycobacterium and non-cardia from other bacteria
  • Acid fast bacteria retain carbolfuchsin and appear red.
  • Non-acid fast bacteria accept the methylene blue counterstain and appear blue
23
Q

Neisser staining method (3)

A
  • It is a test for the presence of polyphosphates stored in the cells
  • Filamentous bacteria will stain purple –> crystal violet
  • Others used are –> methylene blue, chrysoidin
24
Q

The bacterial cell envelope (3)

A

Cytoplasmic membrane - lipid bilayer structure with proteins, it contains NO sterols.
- Function: active transport of metabolites, synthesis of cell wall components, sensory function, electron transport, secretory function

Cell wall - porous layer.
- Function: helps to maintain cell shape, allows diffusion of metabolites, protects the cell from excess of water.

Slime layer - gelatinous layer, composed of polysaccharides and water.
- Function: provides adhesion to various surfaces, inhibits phagocytosis, accumulates water

25
Q

Internal components of bacterial cell (5)

A

Cytoplasm –> similar to the eukaryotes, but more dense and viscous

Bacterial chromosome –> composed of a single, double-stranded, circular DNA located in the nucleoid

Plasmids –> circular, extrachromosomal DNA that can be transferred from one bacterium to another via the horizontal way

Ribosomes –> consist of 50S and 30S subunits forming the 70S ribosome responsible for protein synthesis

Inclusion granules –> they are accumulation of nutrients. Ex: glycogen.

26
Q

External components of bacterial cell (2)

A

Flagella - long filaments of twisted fibrils, begins from the basal body in cytoplasmic membrane and protrudes to the outside.
- Function: movement of bacterium

Pili - hair- like, composed of the fibrous proteins called pilins.
- Function: responsible for the adhesion of bacteria to natural surfaces and horizontal transfer of genes between bacteria

27
Q

Classification according to the number and arrangement of flagella (4)

A

Monotrichous
Amphitrichous
Peritrichous
Lophotrichous

28
Q

Bacterial spores (6)

A
  • dehydrated, multi-shelled structures
  • Function: protects and allows bacteria to live under extreme conditions and exists in the dormant state
  • contains a complete set of chromosomes
  • contains a small concentration of essential proteins and ribosomes and a high concentration of calcium
  • spore forms will NEVER be gram -
  • two peptidoglycan layers and an outer keralin like protein coat
29
Q

Sporogenesis

  • what triggers it
  • 8 steps
A

Depletion of specific nutrients from the growth medium triggers it

  1. DNA condenses and aligns itself in the center of the mother cell
  2. DNA duplicates and the mother cell membrane invaginates to form the developing spore
  3. The mother cell membrane engulfs the developing spore
  4. Peptidoglycan is layed down between the 2 mmebranes to form the cortex
  5. Dipicolinic acid is formed and calcium enters from the outside
  6. As calcium enters, water is removed
  7. A keratin-like protein coat forms and the spore becomes mature
  8. Enzymes destroy the mother cell and the spore is released
30
Q

Germination of bacterial spores (3)

A
  • It is stimulated by disruption of outer coat by mechanical stress, pH, heat….
  • Requires water and a triggering nutrient. Ex: alanine
  • After the process begins, the spore will take up water, swell, shed its coats and produce one new vegetative cell
31
Q

Classification of fungi

A

Look at my summary

32
Q

Morphology and structure of fungi

A

Morphology - yeast, pseudohyphae, hyphae

Structure - look at the pic

33
Q

Classification of protozoa (7)

A

Belong to the kindgom Protista, classified into 7 phyla:

  1. Metamonada: protozoa with flagella
  2. Parabasala: protozoa with flagella
  3. Percolozoa:protozoa with flagella
  4. Euglenozoa: protozoa with flagella
  5. Amoebozoa: protozoa that move like amebae
  6. Sporozoa: non-motile protozoa
  7. Ciliophora: protozoa that move using cilia
34
Q

Morphology and structure of protozoa

A
  • They may contain flagella, cilia or pseudopodia
  • Reproduce asexually
  • Trypanosome brucei gambiense, plasmodium vivax, toxoplasma gondii, leishmania donovanii

-Look at the pic for the structure!!!!!

35
Q

Mycoplasmas (4)

A
  • Smallest free living bacteria
  • Varying shapes –> from 0.2 to 0.3 coccoid forms to rods 0.1 to 0.2 width and 1 to 2 long
  • dont have a cell wall and their cell membranes contain sterol
  • divide by binary fission
36
Q

Spirochetes (4)

A
  • have an endoflagella
  • they rotate as they move
  • undergo asexual transverse binary fission
  • Treponemes, borreliae, leptospires
37
Q

Rickettsiae

  • Morphology (4)
  • Structure (1)
  • Biological properties (3)
A
  • Small, pleomorphic bacteria, they are obligate intracellular parasites, dont have flagella, seen best with Giemsa or Gimenez stains
  • Structurally similar to gram - bacteria
  • Enter eukaryotic cells by attaching to host cell surface receptors and stimulating endocytosis, depend on their host cells for many functions, are able to produce ATP
38
Q

Chlamydiae (4)

A

Pleomorphic bacteria that exists in 2 forms:

  • Metabolic inactive, infectious forms (elementary body with size 0.3-0.4um)
  • Metabolic active, non-infectious forms (reticulate body with size 0.8-1um)
  • Cell wall is composed of a double-layer outer membrane consisting of lipopolusaccharide and major outer membrane protein
  • they are energy parasites because they use host cell ATP for their energy requirements
  • they are obligate intracellular parasites, because they cannot reproduce outside the host cell
39
Q

Life cycle of chlamydiae (6)

A
  1. Elementary body attach to host cell
  2. Elementary body enter host cell by endocytosis
  3. Elementary body is converted to reticulate body
  4. Reticulate body replicate
  5. Reticulate body condensates to form elementary bodies
  6. Elementary bodies are released
40
Q

Actinomyces (6)

A
  • Anaerobic gram + rods
  • they are not acid fast
  • grow slowly in culture
  • lack mitochondria and nuclear membrane
  • inhibited by penicillin but not anti-fungal antibiotics
  • Ziehl-neelsen staining method –> methylene blue, stain blue
41
Q

Acid-fast bacteria (4)

A
  • non-motile, non-spore forming, aerobic rods
  • cell wall is rich in lipids
  • once stained, the rods cannot be decolorized with acid solutions
  • Ziehl-neelsen staining method –> carbolfuchsin, stain red
42
Q

Difference in the cell wall of Gram - and Gram + bacteria

A

Gram - –> contains a thin layers of peptidoglycan, an outer membrane composed of lipopolysaccharides, teichoid acid is ABSENT

Gram + –> cell wall is thick, contains a very thick layers of peptidoglycan, contain teichoid acid running perpendicular to the peptidoglycan sheets

Microbiology (5 decks)

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