Bacteriology Flashcards

1
Q

What are the differences between eukaryotic and prokaryotic cells?

A

Eukaryotic:

  • Nuclei with linear chromosomes
  • Organelles: mitochondria, Golgi apparatus, lysosomes and relatively large ribosomes
  • Larger size: 0.1 – 100 μm
  • Individual cells replicate by mitosis

Prokaryotic :

  • Lack true membrane - bound nuclei
  • Genetic information is contained in a single haploid circular chromosome
  • Small size: 0.5-5 μm
  • Bacteria: Unicellular organisms that replicate by binary fission - Bacteria: extrachromosomal DNA - plasmids
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2
Q

What are the similarities between eukaryotic and prokaryotic cells? (3)

A
  • Cell membrane
  • Cytoplasm
  • DNA present in both (just different location)
  • Ribosomes (but different structure)
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3
Q

What are the different structures of the bacterial ? (the ones they all have) (5)

A
  • Cytoplasm
  • Ribosomes
  • Nucleoid
  • Plasma membrane
  • Complex and rigid cell wall
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4
Q

What are the structures the bacterial can sometimes have? (3-4)

A
  • Capsule
  • Flagella
  • Pili/Fimbriae
    (Endospores)
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5
Q

(OLD) What does the cytoplasm contains?

A
  • MACROMOLECULES (proteins, mRNA, tRNA) + Nucleoid (DNA) and ribosomes (protein synthesis).
  • SMALL MOLECULES : energy sources, precursors of macromolecules, metabolites or vitamins.
  • INORGANIC IONS : for enzymatic activity.
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6
Q

(OLD) What is the functions of the cytoplasm?

A
  • Facilitate chemical reactions

- Dissolve solutes (ex. carbohydrates and proteins)

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7
Q

What is the nucleoid in the prokaryotic cells?

A

It is the location in the prokaryotic cell where primary genetic material is found. Takes 1/3 of the cell.

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8
Q

What is the chromosomal DNA made of?

A

Single haploid circular chromosome containing double-stranded DNA. (Haploid meaning : no additional copies).

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9
Q

What are the ribosomes? Function?

A
  • PROTEINS and RNA

Function: involved in protein synthesis!

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10
Q

What is the plasmid?

A

It is a circular molecule of DNA that replicates separately from the genome.
(several different types may be present in one cell)

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11
Q

Is the plasmid part of the nucleoid?

A

NO!

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12
Q

Is the plasmid genes essential under normal conditions?

A

No, it is not essential.

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13
Q

(Old) What is the functions of the plasmid? (2)

A
  • SPECIAL GENES REPLICATION:
  • Virulence factors: associated with disease
  • Resistance genes: to survive in presence of antibiotics and other toxic compounds.
  • CONJUGATIVE PLASMIDS: cell-to-cell transfer by conjugation (transfer DNA).
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14
Q

(Old) How can we relate ribosomes to medicine? How can they be used?

A

They can be the target for antibiotics.

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15
Q

(Old) What are the different components of the bacterial envelope?

A
  • Cytoplasmic or plasma membrane.
  • Cell wall (peptidoglycan layer)
  • Periplasmic space
  • Capsule (some bacteria)
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16
Q

(Old) Where the plasma membrane located?

A

Innermost membrane, next to cytoplasm.

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17
Q

(Old) What type of bacteria has a periplasmic space?

A

Gram negative

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18
Q

(Old) What are composed the components of the plasma membrane?

A

Phospholipid bilayer (head hydrophilic and tail hydrophobic).

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19
Q

(Old) What can pass by passive diffusion the plasma membrane?

A

Only hydrophobic coumpounds.

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20
Q

(Old) What the different proteins inside the plasma membrane?

A
  • TRANSPORT PROTEINS : for specific transport of molecules into and out of the cell.
  • ENERGY GENERATION COMPONENTS : used to generate ATP.
  • Proteins to work as anchors or assembly of external structures.
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21
Q

What is the main functions of plasma membrane?

A
  • Selective permeable membrane
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22
Q

What are the components of the cell wall? How are they arranged?

A

Peptidoglycan (unique to prokaryotic cells) : NAG + NAM.

Arranged in a mesh-like structure alternating NAG-NAM-NAG-NAM.

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23
Q

(Old) What is the link between each NAG and NAM?

A

Cross-linked with peptides by transpeptidase enzymes called: penicillin-binding proteins (PBPs).

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24
Q

What is the function of the cell wall?

A
  • RIGIDITY

- PROTECTION against mechanical damage and osmotic lysis

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25
Q

What does contains the cell wall of gram +, gram - and mycobateria ?

A

Gram + : (Lipo)teichoic acid: strongly antigenic
–> High resistance to physical disruption and drying

Gram - : Lipopolysaccharides (LPS)
–> Low resistance to physical disruption and drying

Mycobacteria: mycolic acid as virulence factor
–> will not stain = need acid fast stain!

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26
Q

Is there an outer membrane in every bacteria?

A

No, usually common to Gram-negative bacteria.

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27
Q

What are the 2 part of LPS in Gram - ? What is the most important of the 2? What is its function?

A
  • Lipid A : endotoxin that activates immune system and exert harmful effects
  • Polysaccharide chain: antigenicity
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28
Q

What is the function of outer membrane?

A
  • Selective permeability
  • Resistance to large or hydrophobic toxic compounds
  • Tolerance to detergents and bile salts
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29
Q

Is the gram + or gram - that has the thickest cell wall (peptidoglycan layer)?

A

Gram +

30
Q

Is the capsule present in all bacteria?

A

No!

31
Q

What is the capsule?

A

Polysaccharide outer layer!

32
Q

What is the functions of the capsule?

A
  • PROTECTION from adverse environmental conditions
  • Facilitate ADHERENCE to surfaces
  • Help EVADE phagocytosis
  • NUTRIENT RESERVE
33
Q

In what type of cell state are found endospores?

A
  • Cryptobiotic state of DORMANCY –> most durable type of cell found in nature
34
Q

What is the main function of endospores?

A

Ensure survival during adverse environmental conditions

dormant highly resistant bodies

35
Q

What are the only 2 genera that can transform into endospores when exposed to adverse conditions?

A

Clostridium and Bacillus

36
Q

Where is the flagella? Which bacteria specie is most commonly presenting with flagella?

A

On the surface of the bacteria.

–> Present in many species of Gram -

37
Q

Is there always only one flagella and at the same place?

A

No! It can have number of flagella and at different position.

38
Q

What is the function of the flagella?

A

Locomotion or bacterial motility

39
Q

What does the pili/fimbriae look like?

A

Fine, straight, hair-like appendages attached to cell wall.

40
Q

What’s an endoflagella? What movement does it do?

A

Flagella in the periplasmic space = corkscrew-like motility (e.g. spirochete)

41
Q

What are the 2 functions of pili/fimbriae?

A
  • Adhesion to host tissues

- Contribute to antigenicity

42
Q

(Old) What structures contribute to bacterial survival ?

A
  • Plasmid (resistance genes: can survive in presence of antibiotics and other toxic compounds)
  • Endospores (ensure survival adverse environmental conditions)
  • Capsule (protects from adverse environmental conditions)
  • Outer membrane : resistance to large or hydrophobic toxic compounds
  • Cell wall : protects against mechanical damage and osmotic lysis.
43
Q

(Old) What structures contribute to pathogenesis?

A
  • Plasmid : genes associated with disease (virulence factors)
  • Capsule : virulence factor that facilitate adherence to surfaces and interfere with phagocytosis.
  • Pili/Fimbriae : contribute to antigenicity
44
Q

What are the different types of bacterial shapes?

A
  • Cocci
  • Bacilli
  • Budding and appendaged bacteria
  • Others +++ (look at ppt)
45
Q

(+/- old) What are the different types of bacterial arrangements?

A
  • Alone (e.g. coccus)
  • Two (e.g. diplobacilli)
  • Chain (e.g. streptococci or streptobacilli)
  • Encapsulated (e.g. diplococci)
  • Organized bundle (e.g. staphylococci or pallisades in bacilli)
46
Q

What are the 3 exceptions to general bacterial properties?

A
  • Mycoplasma: does not have a cell wall
  • Leptospira: two circular chromosomes
  • Borrelia burgdorferi: linear chromosomes
47
Q

(Old) If you grow two bacteria from the same species, will they absolutely be the same morphology? Why?

A

No, it depends on the culture medium, incubation time, temperature, oxygen or genetic differences.

48
Q

What are the different type of sources of metabolic energy?

A
  • Fermentation
  • Respiration
  • Photosynthesis
49
Q

What are the different nutrients required for different bacterial groups?

A

Carbon and Nitrogen (about 99,9% of bacteria need those nutrient)

50
Q

What are the different types of oxygen requirement fro growth? (4)

A
  • Obligate aerobes (die without O2)
  • Obligate anaerobes (die with O2)
  • Facultative anaerobes (can switch to O2 metabolism to CO2 metabolism)
  • Microaerophile: need a little O2

(Old) Aerotolerant anaerobes (use fermentation, so don’t use O2, but can survive and grow with O2)

51
Q

What are the different classifications of bacteria based on temperature range of growth (from cold to warm)?

Most of them are…

A
  • Psychrophiles (10°C)
  • Psychrotropes (20°C)
  • Mesophiles (35°C)
  • Thermophiles (60°C)
  • HYperthermophiles (90°C)

Most of them are… Mesophiles (like about 37°C)

52
Q

(Old, but good summary) What is the different cell envelope type for the different classes of cell (gram +, gram -, mycobacteria, mollicutes)? From cytoplasm to outside (ECF) for each.

A
GRAM POSITIVE :
- plasma membrane
- periplasmic space (with lipoprotein)
- peptidoglycan
- ECF
GRAM NEGATIVE :
- plasma membrane
- periplasmic space (with lipoprotein)
- peptidoglycan
- another periplasmic space
- outer membrane
- ECF
MYCOBACTERIA : 
- plasma membrane
- periplasmic space (with lipoprotein)
- peptidoglycan
- Mucolic acid on the cell
- ECF
MOLICUTES : 
- plasma membrane, BUT with sterols
- periplasmic space (with lipoprotein)
(No peptidoglycan layer)
53
Q

What color do the gram + and gram - stain?

A

Gram - : pink

Gram + : purple

54
Q

True or false : does bacterial growth curve replicate like virus, by assembly line.

A

False, they replicate by binary fission.

55
Q

(Old) How long can it take to create 2 daughter cells (generation time)?

A

30 minutes to 20 hours.

56
Q

During which phase in bacterial growth curve occurs cell multiplication is at maximal rate?

A

Exponential phase or Logarithmic phase (2nd)

57
Q

During which phase in bacterial growth curve is there no cell division, only increase in size?

A

Lag phase (1st) (active metabolism of cells, but no division yet)

58
Q

In which phase exhaustion of nutrients or accumulation of toxic products occur? And what happens because of it?

A

Maximal stationary phase (3rd).
The growth will cease.
There’s a balance between slow multiplication and death rate.

59
Q

When does the cell division starts to occur?

A

Exponential phase or Logarithmic phase (2nd)

60
Q

What happens after exhaustion of nutrients phase?

A

Decline phase or death phase: progressive death of cells (4th, Last phase)

61
Q

What are the main differences between exotoxins and endotoxins?

A

Exotoxins: proteinaceous toxins made inside the bacteria and released in extracellular enviro.

  • -> exert action on specific cells
  • -> Heat labile

Endotoxins: toxins in the cell wall of the bacteria (e.g. LPS)

  • -> induce inflammation by stimulating the immune system
  • -> Heat stable
62
Q

What is the biofilm made of?

A

Bacteria aggregation (all holding hands!) –> on a surface and enclosed into in a bipolymer matrix surface

63
Q

What is the main function of the biofilm? And where do you usually find it?

A

Because they are all enclosed in the same bipolymer matrix surface they can exchange nutrients
+ they can produce LPS

Usually found in… dental plaques, catheter, urinary tract infection

64
Q

What is quorum sensing? How does it work?

A
  • -> Bacteria produce small signal molecules (pheromones, autoinducers) by which they communicate
  • -> When the population reaches a defined density (a bacterial quorum), instant changes occur in their behaviour (virulence), appearance and metabolism.
65
Q

What the different group behaviors from quorum sensing?

A
Symbiosis
Virulence
Conjugation
Biofilm
Motility
ATB production
Sporulation
Competence
66
Q

How can bacteria transfer virulence between bacteria?

A

By conjugation, transformation or transduction!
• Plasmids (small circular DNA) and bacteriophages (viruses of bacteria) may carry genes for antibiotic resistance, toxins

Most common: conjugation!

(capsules and fimbriae can mediate transfer)

67
Q

See PPT for Fungi, but here are the main points!

A
  • Eukaryotic, non-photosynthetic microorganisms widely distributed in the environment
  • Heterotrophs: produce exoenzymes to obtain nutrients by absorption
  • Cell wall contains chitin (plant-like cell wall).
  • Two major forms: branching hyphae (moulds) and unicellular yeasts
  • Reproduce both sexually (spores) and asexually (spores, budding or fragmentation)
    • Resistant to antimicrobial drugs**
  • Vast majority of fungi are saprophytes and non-pathogenic.
  • Fungal infections are far less common than bacterial infections.
  • Fungi grow aerobically and many are strict aerobes (NEED O2)
  • Mechanisms involved in fungal diseases
    • Tissue invasion (mycosis): E.g. dermatomycoses, dermatophytoses
    • Toxin production (mycotoxicosis): E.g. ingestion of fungal toxins pre-formed in stored food or standing crops
    • Induction of hypersensitivity (less common): E.g. chronic pulmonary disease in cattle and horses
68
Q

True or False. An infection does not always result in disease! But all infectious diseases are
communicable and not all communicable (reportable) diseases are infectious.

A

False!
(true part: An infection does not always result in disease!)
–> All communicable (reportable) diseases are infectious, but not all infectious diseases are
communicable

69
Q

Bacteria are usually intracellular or extracellular?

A

Extracellular!

70
Q

What is the purpose of being a pathogen or at times adopting a pathogenic lifestyle?

A

Enhance transmission!

71
Q

WHERE or WHEN would you like to collect fungi and bacteria?

A

Fungi: specimens should be collected from the periphery of active lesions

Bacteria: collect before starting any antimicrobial therapies