(6,7) TOB Bacteria and Viruses Flashcards
What is infection?
The multiplication/colonisation of a pathogenic microbe on/in a susceptible host with associated dysfunction/damage.
What causes infection?
Pathogenic microbes
What three stipulations are used to determine whether a pathogen causes a disease?
- The agent must be shown to be present in every case of the disease by isolation in pure culture
- The agent must not be found in cases of other disease
- Once isolated, the agent must be capable of reproducing the disease in experimental animals, and must be recovered from the experimental disease produced.
Why do particular individuals get particular infections?
- Weakened immune systems
- Poor nutrition
- Poor living circumstances
- No access to health care (vaccinations)
- Genetic predisposition
- Lifestyle (e.g. STDs)
What influences the outcome of infection?
The host’s immune system, the affected body systems and the drugs used.
What are the key properties of a Eukaryote?
No cell wall No envelope No capsid Membrane bound organelles Nucleus DNA and RNA No pili or flagella No reverse transcriptase
What are the key properties of a Bacterium?
Peptidoglycan or lipopolysaccharide cell wall No capsid No membrane bound organelles No nucleus – Circular DNA DNA and RNA Pili, flagella No reverse transcriptase
What are the key features of a virus?
Can be enveloped No organelles – obligate intracellular parasites Can have capsids DNA or RNA No pili or flagella Can have reverse transcriptase
What does gram staining allow us to do?
detect and begin to classify most bacteria
What are the two classifications of bacteria within gram staining?
. Bacteria can be classified as Gram positive or negative depending on its cell wall.
What colour are gram negative bacteria in a Gram stain and vice versa?
Gram negative bacteria are stained red whereas Gram positive bacteria are blue after staining.
Describe the process of gram staining
- Positively charged crystal violet binds to negatively charged cell components
- Iodine forms a large molecular complex with crystal violet
- Acetone or methanol extract the complexes through the Gram-negative cell wall but not through the Gram-positive
- A red dye is used to stain the now unstained Gram-negative cells
What do acid fast stains allow us to do?
detect the bacterial causes of tuberculosis and leprosy (mycobacteria) – bacteria that cannot be identified by gram staining.
What is a pathogen?
a bacterium, virus, or other microorganism that can cause disease
What is a non pathogen and what roles do they peform?
a bacterium that doesn’t cause disease. Many non-pathogens perform essential ecological roles.
What is the significance of genome compositon in the classification and detection of viruses?
RNA viruses are more likely to mutate, as RNA is less stable. DNA more stable.
What is the significance of a viral envelope, and whether it is present for the classification and detection of viruses?
If a virus has an envelope it’s more easily sterilised as if holes are punched in the envelope the virus cannot survive
What is the significance of replication strategy for classification and detection of viruses?
RNA viruses can use reverse transcriptase (HIV), DNA viruses can use cell machinery (HPV), or a virus can carry its own replication enzymes.
Classify Hepatitis B virus and give disease association
DNA Enveloped
Inflamed liver
Classify Herpes virus and give disease association
DNA Enveloped
Oral/genital
Classify smallpox virus and give disease association
DNA enveloped
Smallpox
Classify and give disease association of HPV
DNA non-enveloped
Warts, Cervical Cancer
Classify and give disease association of HIV
RNA enveloped
AIDS
Classify and give disease association of Rubella
RNA enveloped
Rash, congenital rubella syndrome
