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BFI: Biology > Bacteria > Flashcards

Bacteria Flashcards

1
Q

Cell

A

Basic unit of life

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2
Q

2 groups based on cellular organisation

A

Prokaryotes - bacteria

Eukaryotes - Animals, plants, fungi, algae

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3
Q

Why isn’t a virus a group?

A

It relies on the host’s molecular mechanism

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4
Q

What bacteria does not have a cell wall?

A

Mycoplasmas - obligates intracellular parasites

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5
Q

Function of cell wall

A

Define shape, gives rigidity + resists turgor pressure

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6
Q

Cell wall made up of?

A

Semi - rigid wall composed of peptidoglycan (murein)

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7
Q

Mycobacteria

A

Cell wall rich in mycelia acid + PDC

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8
Q

What bacteria takes up more gram stain?

A

Gram-positive

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9
Q

Transpeptidation

A

process of cross-linking peptidoglycan chains

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10
Q

What does PDC monomer consist of>

A 
NAG = N-acetylglycosamine
NAM = N-acetylmuramic acid
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11
Q

What binds NAG + NAM?

A

Glycosidic acid

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12
Q

Gram-positive

A

Thickest bacterium = many interconnecting layers of peptidoglycan (20-80nm)
Teichoic + Lipoteichoic acid is embedded in wall
- they help movement of molecules in + out bacterium
Various protein embedded
- Adhesins = adhere to host
- Enzymes = damage host tissues
- Invasins = invade host cells
Cocci

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13
Q

Gram-negative

A

Thinner bacterium - get layers of PDC (2-3nm)
Outer membrane = rich lipopolysaccharide (LPS)
- LPS linked to PDC by lipoprotein anchor
various proteins in outer membrane

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14
Q

What has an acid fast wall cell wall

A

Mycobacterium (gram-positive)

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15
Q

What stain does mycobacterium take up?

A

Ziehl-Neelsen stain

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16
Q

Function of Mycolic acid

A

Disrupt entry of molecules causing slow growth, giving greater resistance to chemical agents + enzymes

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17
Q

Unique chemical structures in prokaryotic cells

A
  • Fimbriae/pili
  • Capsule/slime layers
  • Flagella
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18
Q

Fimbriae/pili

A

involved in attachment of surfaces - other cells

  • mainly gram-negative
  • coated with proteins
  • communication + exchange of genetic information
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19
Q

Capsules/slime layers

A

Protection from immune evasion (phagocytosis) + attachment

- Biofilms

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20
Q

Biofilms

A

Collection of microorganism surrounded by the slime they secrete - attached to inert/living species

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21
Q

Flagella

A

Cells swim through environment

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22
Q

Endospores

A

major source of infection - produced when starved or adverse environment
Exists in state of dormancy - persist for long periods of time
Highly resistant to extreme pH, temperature, radiation, desiccation, chemical agents
not all gram-positive bacteria form spores

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23
Q

What bacterium form spores?

A

Bacillus anthraces
Bacillus cereus
Clostridium difficile
Clostridium tetani

24
Q

Bacterial microflora

A

The bacteria all over the body may not be damaging but protective or beneficial.
Also called microbiome + commensal bacteria
- tend to be low virulence
- loose interaction with epithelial surfaces ( Skin, GI tract)
- essential for normal wellbeing
- kept in balance by host immune responses
- reduce risk of colonization by pathogenic bacteria

25
Exotoxin pathogenicity
made by bacteria + secreted out f the bacterium produce local/systemic infections different types Bacteria secrete enzymes + molecules which - damage immune response molecules - damage cell + tissue
26
Different types of exotoxins
Cytolytic toxins - damage cell membrane A-B toxins - disrupt protein synthesis Super antigen - activation of T cell response in antigen absence / diversion of immune response
27
Different types of exotoxins
Cytolitic toxins - damage cell membrane A-B toxins - disrupt protein synthesis Super antigen - activation of T cell response in antigen abscence / diversion of immune response
28
Endotoxins pathogenicity
``` Lipopolysaccharide in gram-negative (released upon lysis of bacterial cell) + contains - lipid A - core polysaccharide - O-polysaccharide Endotoxins cause: - immune system activation - fever/diarrhoea - release cytokines - inflammation ```
29
What has a similar response as endotoxins pathogenicity?
Teichoic acids in gram-positive
30
Environmental changes where microbes are found to cause bacterial infections
Invasion of wound Antibiotic therapy Nosocomial infections Latrogenic infections
31
Incidental exposure to cause bacterial infections
``` GI infections - E.coli - Campylobacter - Vibrio Cholera Person-person - Neisseria meningtidis - Chlamydia trachmatis - Mycobacterium tuberculosis - Neisseria gonorrhoea Environmental - Clostridium retain lives in soil - Legionella = failure to maintain air condition ```
32
How do we identify?
Samples | Methods
33
Methods of identification
Microscopy, culture, serology, molecular
34
Samples of identification
Timing, biopsy, environmental, body fluids, collection/transport
35
Symptoms of infection depend on
1) Site of infection 2) No. of pathogens/site of inoculums 3) ability of pathogens to colonise host 4) Virulence factors produced toxins 5) Ability to evade immune response 6) Age/condition of host
36
Asymptomatic carriers
Carry pathogenic bacteria but no sign of disease
37
Infectiousness
Ease of spread in a population
38
Pathogenicity
Ability to cause disease
39
Pathogenicity factors
e.g. adherence, colonisation, invasion, toxins
40
Virulence
Power to cause severe disease e.g. toxin, resistance
41
Intoxication/food-poisoning
Ingestion of bacterial-derived toxin, often in absence of bacterium e.g. toxin in/on food
42
Infection
Microorganism established, growing and/or spreading on or within host
43
Attached to each NAM is...
5 amino acids | - but 1 amino acid is removed during assembly = NAM-tetrapeptide
44
How to reduce risk of colonization by pathogenic bacteria
Modify local pH Block host binding sites Secrete toxic metabolites
45
What can start a systemic cellular responsed
Bacterial derived toxins
46
Disease
Recognisable + defined damage/injury to host that impairs host function
47
Biological agent
Any microorganism, cell culture or toxin able to enter human body + cause harm
48
Typing of E.coli strain O157:H7
Entero-haemorrhagic E.coli 170 O antigens (LPS) 100 K antigens (Capsule) 50 H antigens (Flagella)
49
How can bacterial infections arise
Incidental exposure/poor or inadequate hygiene/precautions - GI infections - person - person - Environmental Environmental change where microbe is found - Wound invasion - Antibiotic therapy - Nosocomial infections - Latrogenic (caused by doctors) infection
50
How does Clostridium difficile spread
Poor hygiene + inadequate disinfection
51
How can resistance arise in Clostridium difficile
Inappropriate use of antibiotics + some bacteria have natural resistance (waxy cell wall of Mycobacteria disrupt entry of antibiotics)
52
Routes of entry of into host, cycling + transmision
1 )Exposure 2) Adherence 3) Invasion 4) Colonisation + growth 5) Toxicity 6) Tissue damage + disease 5) Invasiveness 6) Tissue damage + disease / further exposure back to (1)
53
Cytolytic toxin
Disrupt cell membrane
54
A-B toxins
disrupt protein synthesis
55
Super-antigen toxins
activate T cell response in antigen absence

BFI: Biology (9 decks)

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