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Foundations of health and disease > Bacteria > Flashcards

Bacteria Flashcards

1
Q

Describe the differences between eukaryotic and prokaryotic cells

A
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2
Q

what is the microbiome

A

The microbiome is the genetic material of all the microbes -bacteria, fungi, protozoa and viruses - that live on and inside the human body

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3
Q

List the major types of micro-organism which cause human infectious diseases

A

viruses
prokaryotes
eukaryotes

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4
Q

what are prokaryotes

A

Simple, unicellular organisms lacking a defined nucleus, mitochondria or other membrane-bound organelles

protect skin/epithelial tissue from invasion

help food digestion Biotechnology industry

bacteria

archaea

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5
Q

what are the subdivisions of eukaryotes

A

**eukaryotes**

fungi

protists

  • protozoa
    • A huge family of single-celled eukaryotic parasites
    • Major tropical and zoonotic diseases
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6
Q

How are bacteria named

A

Shape
Round - ‘coccus / cocci’
e.g Streptococcus sp, Enterococcus sp

Long – ‘bacillius / bacilli’
E.g. Enterobacter sp.

A few are spiral / branched (filamentous), comma shaped

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7
Q

what is gram staining

A

Ability to take up stain based on the thickness and accessibility of cell wall peptidoglycans

  • gram-positive bacteria have a cell wall mainly consisting off peptidoglycan
  • gram-negative bacteria have a very thin peptidoglycan layer and an outer membrane
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8
Q

how do you gram stain

A

Dry on glass plate
Stain with ‘crystal violet’ and set with iodine
Decolourise with alcohol/ acetone
Counterstain with safranin (pink colour)

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9
Q

what are examples of gram positive and negative bacteria

A
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10
Q

why do mycobacteria have different gram stains?

A

Basically a Gram positive cell wall
Don’t stain Gram positive
Very thick lipid membrane (mycolic acid mycomembrane) anchored to peptidoglycan layer
Intracellular survival

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11
Q

what is an o antigen

A

repeating glycan polymer (varies based on strain). Immunogenic.

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12
Q

what is lipid A

A

anchor for Lipopolysaccharide. Immunogenic

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13
Q

features of a bacterial capsule

A
  • Polysaccharide coat
  • ‘hides’ immunogenic cell wall
  • Immunity requires antibodies to the capsule
  • Metabolic burden on the bacterium
  • Confers virulence e.g.
    • Haemophilus influenzae
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14
Q

explain the mobile genetic element- ribosome

A

Engines of protein synthesis
70S (sedimentation rate)
Smaller than in eukaryotes (80S)
Subunits 50S and 30S
Each contains RNA and proteins
Bacterial RNA
Target of antibiotics
Diagnostic tests

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15
Q

explain the mobile genetic element- plasmid

A

Circular ‘extra-chromosomal’ DNA
Independently replicating
Passed down to progeny

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16
Q

explain the mobile genetic element- transposons

A

DNA sequences that are able to move location in the genome.
Encode transposase
Plus other genes
Mobile between
genomic and plasmid DNA

17
Q

gene regulation in bacteria

A

Bacteria sense and adjust to their environment
Altered growth rate
Regulation of metabolic pathways
Regulate virulence factors
Adhesion molecules
Enzymes to degrade host proteins
Degrade immune mediators
Lyse host cells
Exponential phase ≈ superficial infection / bacteraemia
Stationary phase ≈ abscess

18
Q

how do bacteria grow?

A

Bacteria may grow in clusters or chains
Especially important for Gram positive cocci

19
Q

bacterial growth patterns

A

Microscopic view:
Form chains / clusters

On solid culture medium:
Form colonies – different sizes / shapes
Excrete enzymes, waste products etc into environment

20
Q

requirements for bacterial growth

A

Atmosphere
Nutrients

21
Q

what are features of aerobes

A

Use O2 as final electron acceptor (very efficient)
E.g., oxidation of glucose to CO2 and H2O
Some are anaerobes (obligate anaerobes)
Fermentation - final electron acceptor is organic molecule
E.g., glucose to lactic acid
ok when substrates are plentiful
Oxygen is usually toxic to anaerobic bacteria
Some are facultative anaerobes
Can switch between aerobic and anaerobic metabolism

22
Q

what molecules do bacteria have to import

A

Purines and pyrimidines
Amino acids
Vitamins
Escherichia coli (E.coli)
Needs glucose and inorganic salts only
Very easy to grow in the laboratory
Treponema pallidum (cause of syphilis)
Specialised enriched medium
Difficult to grow

23
Q

what is the lag phase

A

No increase in cell numbers
Adjustment to new environment
Gene regulation

24
Q

what is the stationary phase

A

Nutrients become depleted
Metabolites build up
Division stops
Gene regulation

25
Q

what is the rate of exponential growth

A

The rate of exponentialgrowthof abacterial cultureis expressed as generation time, also the doubling time of thebacterialpopulation. Generation time (G) is defined as the time (t) per generation (n = number of generations).

26
Q

what is the exponential phase

A

Cell doubling
Slope of the curve = growth rate of the organism in that environment

27
Q

what is the death phase

A

Exhaustion of resources
Toxicity of environment

28
Q

what are the rod-shaped bacteria called

A

bacillus

29
Q

what are the 3 types of bacillus

A
30
Q

what is a spherial shaped bacteria called

A

coccus

31
Q

what is a curved shaped bacteria called

A

vibrio

32
Q

what is a oblong shaped bacteria called

A

coccobaccilus

33
Q

what is a losely coiled bacteria called

A

spirillum

34
Q

what is a tightly coiled bacteria called

A

spirochette

35
Q

what are the 6 different types of cocci bacteria

A
36
Q

what are the growth requirements of bacteria in a lab

A

Gram staining for bacteria
Samples from sterile site
A single pathogen expected

37
Q

what is chemotherapy

A

use of synthetic chemicals capable of destroying infectious agents

Foundations of health and disease (21 decks)

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