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BM211: Introduction to Microbiology > Block B Lecture 1 - Gram Positive Bacteria > Flashcards

Block B Lecture 1 - Gram Positive Bacteria Flashcards

1
Q

What is the difference between gram-positive and gram-negative bacteria?

A

Gram positive bacteria have a thick peptidoglycan layer and no outer lipid membrane whereas gram negative bacteria have a thin peptidoglycan layer and have an outer lipid membrane

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2
Q

State the 9 taxonomic ranks in order from highest to lowest.

A

Life
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

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3
Q

What are the 4 main phyla of bacteria?

A

Proteobacteria (Pseudomonas)
Actinobacteria (Actinomycetota)
Firmicutes (Bacillota)
Bacteroidetes (Bacteroidota)
(Part 1, Slide 2)

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4
Q

What feature differentiates firmicutes from actinobacteria?

A

Their g+c content in their genomes - actinobacteria has more

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5
Q

Up to what percentage of a gram positive bacterial cell can be composed of peptidoglycan?

A

Up to 90%
(Part 1,Slide 4)

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6
Q

What is commonly embedded in cell walls?

A

Teichoic acids
(Part 1, Slide 4)

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7
Q

What are lipoteichoic acids?

A

Teichoic acids covalently bound to membrane lipids
(Part 1, Slide 4)

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8
Q

What is cell morphology?

A

Cell shape
(Part 1, Slide 5)

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9
Q

What are 3 major bacterial cell morphologies?

A

Coccus (spherical or ovoid)
Rod (cylindrical shape)
Spirillum (Spiral shape)
(Part 1, Slide 5)

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10
Q

Other than coccus, rod and spirillum, what are 3 other bacterial cell morphologies?

A

Spirochetes, appendaged and filamentous
(Part 1, Slide 5)

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11
Q

What are 3 major gram positive bacterial phyla?

A

Actinobacteria
Tenericutes
Firmicutes
(Part 1, Slide 6)

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12
Q

What are 3 genera in the Actinobacteria phylum?

A

Coryneform bacteria
Mycobacterium
Streptomyces
(Part 1, Slide 6)

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13
Q

State 2 examples of Corynebacterium species and what they do.

A

C.diptheriae which causes diphtheria and C.glutamicum which is used industrially to produce monosodium glutamate (MSG)
(Part 2, Slide 2)

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14
Q

What shape are bacteria in the Mycobacterium genus?

A

Rod shaped
(Part 2, Slide 3)

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15
Q

What phylum is the mycobacterium genus in?

A

Actinobacteria phylum
(Slide 3)

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16
Q

Name 2 species in the mycobacterium genus and what they do?

A

M. tuberculosis which causes tuberculosis and M. leprae which causes leprosy
(Part 2, Slide 3)

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17
Q

What are 2 genus of bacteria in the actinobacteria phylum with the filamentous morphology?

A

Streptomyces
Nocardia
(Part 2, Slide 4)

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18
Q

What percentage of antibiotics do streptomyces and norcardia bacteria make up?

A

70%
(Part 2, Slide 4)

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19
Q

What are 2 key genera in the Tenericutes (Mycoplasmatota)?

A

Mycoplasma and Spiroplasma
(Part 2, Slide 5)

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20
Q

What are mycoplasma and Spiroplasma bacteria?

A

They are bacteria which lack cell walls, and are parasites that inhibit plant and animal hosts and are some of the smallest organisms capable of autonomous growth
(Part 2, Slide 5)

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21
Q

Mycoplasma cells are pleomorphic - what does this mean?

A

They can be different morphologies, they can be either cocci or filamentous of various lengths
(Part 2, Slide 5)

22
Q

What are 2 key genera in the firmicute phylum?

A

Lactobacillus and Streptococcus
(Part 2, Slide 6)

23
Q

What are firmicute bacteria?

A

Fermentative bacteria that produce lactic acid from lactose
(Part 2, Slide 6)

24
Q

What are lactobacillus bacteria?

A

Rod-shaped bacteria which grow in chains and are common in dairy products, they are also resistant to acidic conditions and can grow in a pH as low as 4
(Part 2, Slide 6)

25
Q

What are streptococcus bacteria?

A

Coccus-shaped bacteria which grow in chains and play important roles in the production of buttermilk, silage and other products
(Part 2, Slide 7)

26
Q

What genus in the firmicute phylum are the genus of dairy significance?

A

Lactococcus
(Part 2, Slide 7)

27
Q

What are 2 genera in the firmicute phylum which are pathogenic, and what do they cause?

A

Enterococcus - cause urinary tract infections (UTIs), bacteraemia (the presence of bacteria in the blood), endocarditis (inflammation of the endocardium), diverticulitis (inflammation of a diverticulum) and meningitis (inflammation of the protected membranes covering the brain)
Streptococcus - plaque and pathogens
(Part 2, Slide 7)

28
Q

What are staphylococcus bacteria?

A

They are common commensals of humans and animals
(Part 2, Slide 8)

29
Q

What is a commensal?

A

An organism that uses food supplied in the internal or the external environment of the host, without establishing a close association with the host
(Part 2, Slide 8)

30
Q

Where are the bacillus, clostridium and sporosarcina genera of the firmicutes generally found?

A

In soils
(Part 3, Slide 2)

31
Q

Why are spores advantageous?

A

As they are resistant to everything
(Part 3, Slide 3)

32
Q

What is B. subtilis to E.coli?

A

It’s gram positive equivalent in the context of a model organism
(Part 3, Slide 3)

33
Q

Are clostridium bacteria aerobic or anaerobic?

A

Anaerobic
(Part 3, Slide 4)

34
Q

How do clostridium bacteria produce ATP?

A

By substrate level phosphorylation, though some clostridium species undergo stickland reactions (metabolism of pair of amino acids)
(Part 3, Slide 4)

35
Q

What are 3 clostridium species that cause disease?

A

C. botulinum - causes botulism
C. tetani - causes tetanus
C. perfringens - causes gangrene
(Part 3, Slide 4)

36
Q

What does bacillus anthracis cause?

A

Anthrax
(Part 3, Slide 5)

37
Q

What is the life cycle of bacillus anthracis?

A

1.Animal ingests spores hidden in grass
2. The spores germinate inside the animal.
3. The bacilli then multiply releasing toxins and stress factors and also creates capsules and S-layers
4. The bacilli then sporulate and plant themselves in grass so the cycle can continue
(Part 3, Slide 5)

38
Q

What are the 3 forms of anthrax?

A

Cutaneous (infect bite , cut etc)
Gastrointestinal - from eating contaminated meat
Inhalational (pulmonary) - from inhaling spores
(Part 3, Slide 6)

39
Q

What can all 3 forms of anthrax progress to?

A

Fatal systemic anthrax
(Part 3, Slide 6)

40
Q

What is the structure of the bacterial capsule of bacillus anthracis?

A

A linear polymer of γ –D-glutamic acid
(Part 3, Slide 7)

41
Q

What is the purpose of the capsule of bacillus anthracis?

A

It protects it from phagocytosis and contributes to its ability to evade the host’s immune response
(Part 3, Slide 5)

42
Q

What is the structure of the S-layer of bacillus anthracis?

A

Proteinaceous procrystalline sheath
(Part 3, Slide 7)

43
Q

What is the purpose of the S-layer of bacillus anthracis?

A

It contributes to bacterial adhesion, protecting against host defences and modulation of host responses
(Part 3, Slide 5)

44
Q

What barrier must toxins cross?

A

The cell membrane
(Part 3, Slide 8)

45
Q

What are AB toxins?

A

Toxins with an intracellular target which have two functionally distinct regions (A&B)
(Part 3, Slide 8)

46
Q

What do the A and B regions of an AB toxin do?

A

The A region has enzymatic activity whereas the B region is responsible for the host cell binding or the entry of the A region into the cell
(Part 3, Slide 8)

47
Q

What 2 ways can AB toxins operate in?

A

A single polypeptide that is proteolytically cleaved at a later stage
Separate polypeptides that subsequently assemble
(Part 3, Slide 8)

48
Q

How does the Primary Antigen (PA) trigger itself, Lethal Factor (LF) and Edema Factor (EF) to enter a cell via endocytosis and afterwards how is translocation of EF and LF triggered?

A

The primary antigen (PA) is released from bacillus anthracis cell as an 83 KDa precursor, and it then binds to PA receptors on many cell types. A 20 KDa fragment is cleaved from the PA and the 63 KDa fragment heptamer, which exposes lethal factor (LF) and edema factor (EF) binding sites. EF and LF binding triggers endocytosis of the whole complex and acidic pH triggers translocation of EF and LF
(Part 3, Slide 9)

49
Q

What does Lethal Factor (LF) do after it enters the cell?

A

LF enters the cytosol, and cleaves the N terminal portion of Mitogen Activated Protein Kinases (MAPKKs)
MAPKKs are involved in signalling pathways responsible for TNF and interleukin cytokine release which can induce cellular necrosis and toxin induced shock
(Part 3, Slide 9)

50
Q

After lethal factor (LF) enters the cell, what happens to edema factor (EF)?

A

It remains membrane associated and greatly increased cAMP concentration which can also influence cytokine production. It may also increase host susceptibility
(Part 3, Slide 9)

BM211: Introduction to Microbiology (21 decks)

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