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EMS - Mechanisms of Disease > Human Microbiota Intro (9) > Flashcards

Human Microbiota Intro (9) Flashcards

1
Q

What are micro-organisms that cause disease called?

A

Virulent/pathogenic

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2
Q

Akaryote

A

Without a nucleus

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3
Q

Prokaryote

A

Genetic material in a single DNA chain, not enclosed in a nucleus (bacteria)

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4
Q

Eukaryote

A

Distinct nucleus (protocists, fungi, plants, animals)

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5
Q

Koch’s postulates

A

Robert Koch’s criteria used to decide if microorganism caused a disease

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6
Q

Koch’s postulate for genes

A

Genes encode virulence factors
- The gene encoding the trait of interest should be present and transcribed/translated in a virulent strain and be silent in a strain that does not cause disease; disruption of the gene in a virulent strain should result in the formation of a strain that is incapable of casing disease;

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7
Q

Problems with Koch’s postulates

A
  • Difficulty of isolation the causative agent
  • Impossible to grow some pathogens in artificial culture
  • Ethical objections
  • Animal models not sufficient/don’t behave same as humans
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8
Q

What are Viruses?

A

Obligate intracellular parasites

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9
Q

What are viruses comprised of?

A

Nucleic acid (DNA/RNA) core wrapped in a protein coat (capsomeres), some have a lipid envelope

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10
Q

Why are retroviruses unusual?

A

The virion carries an RNA copy of the genome but upon infection a host cell cDNA copy of virus genome is made using reverse transcriptase

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11
Q

Bacteriophage

A

Attacks bacteria

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12
Q

Bacterial shapes

A

Round, rod-shaped, icosahedral, brick-shaped, bullet-shaped

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13
Q

Viroids

A

Naked, infectious RNA molecules - plants suffer

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14
Q

Prions

A

Causes spongiform encephalopathies e.g. BSE/CZJ

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15
Q

Microfungi

A

Eukaryotic

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16
Q

What are most microfungi’s cell wall made of?

A

Chitin (polymer of N-acetyl glucosamine)

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17
Q

Where else is chitin found?

A

Exoskeleton of arthropods e.g. insects

18
Q

Moulds

A

Fungi that grow in mats of tiny filaments (hyphae), form mats (mycelia), can be subdivided into separate compartments by cross walls (septa), multicellular organisms related to mushrooms

19
Q

What genus is most common fungi?

A

Cladosporium

20
Q

Yeast

A

Unicellular fungi e.g. Saccharomyces cerevisiae

21
Q

What diseases do moulds form?

A

Superficial infections e.g. ringworm and athlete’s foot

22
Q

What diseases do yeast form?

A

Thrush by Candida albicans

23
Q

Protista

A

Unicellular eukaryotes, many free-living, some cause serious infections, can infect any human tissue

24
Q

How are protista spread?

A
  • Produce cysts to survive outside the body
  • Insects
  • Sex
25
Q

Classes of protista

A
  1. Apicomplxa (sporozoa)
  2. Flagellate protista
  3. Ciliate protista
  4. Amoebae
26
Q

Examples of infections caused by protists

A

Toxoplasmosis, amoebic meningitis, malaria, trypanosomiasis, leishmaniasis (Kala-Azar), amoebic dysentery, diarrhoea

27
Q

Protista and vaginal infections

A

Caused by Trichomonas vaginalis, causes foul-smelling vaginal discharge, men can be asymptomatic carrier/balantis

28
Q

Bacteria

A

Lack a membrane-bound nucleus/prokaryotes, small minority cause disease

29
Q

Common shape of bacteria

A

Round/cocci or rod-shaped/bacilli, few are comma-shaped/spiral

30
Q

Gram reaction

A

Ability to retain crystal violet-iodine dye complex when treated with acetone/alcohol

31
Q

Gram +ve bacteria

A

30-40 layers of peptidoglycan

32
Q

Gram -ve bacteria

A

Outer contains lipopolysaccharide, lipid A on surface acts as endotoxin > gram-negative shock

33
Q

How are bacteria motile?

A

Flagella

34
Q

What are fimbriae?

A

Hair-like structures that aid adhesion (gram -ve)

35
Q

What are pili?

A

Tubes the join two cells together during conjugation to exchange genetic material (gram -ve)

36
Q

What is a capsule?

A

Protects bacterium, even within phagocytes, preventing death

37
Q

Why do some bacteria produce slime?

A

Helps stick to surface

38
Q

What are endospores?

A

Resist a range of hazardous environments and protect against heat, radiation and desiccation (only few species have)

39
Q

Spread of infection

A
  • Droplet
  • Faecal-oral
  • Sexually
  • Direct inoculation
  • Animals
  • Zoonoses (infection through animals being a reservoir)
  • Fomites
  • Intoxication
40
Q

Examples of diseases acquired through drinking water

A

Typhoid, cholera, dysentery, hepatitis A and poliomyelitis

41
Q

Virulence factors

A

Traits used to complete the cycle of infection

EMS - Mechanisms of Disease (21 decks)

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