TOB S4 - Viruses and Bugs in the System (from S3) Flashcards Preview

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Flashcards in TOB S4 - Viruses and Bugs in the System (from S3) Deck (25):
1

What is an infection? (Answer as if asked by a layperson)

The multiplication/colonisation of pathogenic microbes in a susceptible host with associated damage/dysfunction.

2

What causes infection?

Answer as if to a layperson

Pathogenic microbes

3

What makes a person susceptible to infection?
Answer as if to a layperson

Weakened immune system
Poor nutrition
Poor living circumstances
No access to healthcare (eg vaccines)
Genetic predisposition
Lifestyle (eg STDs)

4

What influences outcome of infection?
Answer as if to a lay person

The host's immune system
Affected body systems
Drugs used

5

Compare and contrast eukaryotes, bacteria and viruses
Hint: think cell coatings, organelles and genetic info

Eukaryotes:

No cell wall
No envelope
No capsid
Membrane bound organelles
Nucleus
DNA/RNA
No pili or flagella
No reverse transcriptase

Bacteria:
Peptidoglycan or lipopolysaccharide cell wall
No envelope
No capsid
No membrane bound organelles
No nucleus
Circular DNA
DNA/RNA
Pili/flagella
No reverse transcriptase

Viruses:
No cell wall
Can be enveloped
Can have capsids
No organelles - obligate parasites
DNA OR RNA
No pili or flagella
Can have reverse transcriptase

6

What is the use of the gram staining process and what is the result of gram staining?

Allows us to detect and classify most bacteria

Gram negative = stained red
Gram positive = stained blue

7

Describe the gram staining process

Crystal violet binds to negatively charged cell components

Iodine forms a complex with the crystal violet

Acetone or methanol extracts the complex through negative but not positive cells

Red dye now used to stain unstained negative cells

8

What do acid fast stain allow us to do?

Detect bacterial causes of leprosy and tuberculosis (mycobacteria) that cannot be detected by gram staining

9

What's the distinction between pathogenic and non-pathogenic micro-organisms?

Pathogenic cause disease, non-pathogenic don't. Many non pathogenic perform vital ecological roles

10

What is the importance of genome composition in viruses?

RNA viruses more likely to mutate, DNA more stable

11

What is the significance of the envelope to viral sterilisation?

Enveloped viruses easier to sterilise as if holes are punched in the envelope the virus cannot survive

12

What are the 3 different viral replication methods?

RNA viruses replicate using reverse transcriptase (eg HIV)

DNA viruses use cellular machinery to replicate (eg HPV)

Or a virus can use its own replication enzymes

13

Give 3 types of DNA/Enveloped virus and an example of a condition they cause.

Hep B - inflamed liver

Herpes - oral/genital herpes

Smallpox - smallpox

14

Give an example of a DNA/non-enveloped virus and associated conditions

HPV - warts, cervical cancer

15

Give 4 examples of RNA/Enveloped viruses and their associated conditions

HIV - AIDS

Rubella - rash, congenital rubella syndrome

Rotavirus - diarrhoea

Coronavirus - SARS

16

Give 2 examples of RNA/non-enveloped viruses and their associated conditions

Polio - inflammation of the spinal cord

Hep A - Liver disease

17

What is the target of the Beta-lactam antibacterials?

Cell Wall

18

Name some common Beta-lactam antibiotics

Penicillin
Amoxicillin
Flucloxacillin
Cephalexin

19

what are the different habitiats that microbes might be found in?

Soil
Air
Bodily fluids
Animals
Plants
Humans

20

Define the term 'reservoir'

Any substance in which an infection agent lives/multiplies

21

What is a 'Source' of microbes?

A readily avaliable form of infection agent

22

What are the different modes of transmission for microbes?

Ingestion
Inhalation
Physical contact
Inoculation
Sexual transmission

23

Define the term 'Carriage'

Passage taken by micro-organism into the body

Eg. nasal, throat

24

What are 'normal flora'?

Non-pathogenic bacteria naturally found in the body

Eg. in the gut

25

What is a 'Commensal' in terms of microbes?

A symbiotic relationship in which only one organism derives benefit (microbe) and one is unaffected (host). This is the time when the microbe might be replicating or awaiting compromise of the immune system.