TOB S4 - Viruses and Bugs in the System (from S3) Flashcards
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.
What causes infection?
Answer as if to a layperson
Pathogenic microbes
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)
What influences outcome of infection?
Answer as if to a lay person
The host’s immune system
Affected body systems
Drugs used
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
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
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
What do acid fast stain allow us to do?
Detect bacterial causes of leprosy and tuberculosis (mycobacteria) that cannot be detected by gram staining
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
What is the importance of genome composition in viruses?
RNA viruses more likely to mutate, DNA more stable
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
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
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
Give an example of a DNA/non-enveloped virus and associated conditions
HPV - warts, cervical cancer
Give 4 examples of RNA/Enveloped viruses and their associated conditions
HIV - AIDS
Rubella - rash, congenital rubella syndrome
Rotavirus - diarrhoea
Coronavirus - SARS
