Life Sciences 2 - Test 3 - Short Answer Questions Flashcards
How does bacteria cause disease? and what are the 4 ways bacteria can spread?
Using cells for food: The bacteria break down healthy cells for food, destroying tissues.
Releasing toxins: The bacteria produce a toxin (poisonous protein) that is released into the bloodstream where it can travel throughout the body, disrupting normal activity and damaging tissues.
4 ways diseases can spread:
- Airborne/droplet
- Contact
- Vectors
- Ingested
Explain Sporulation. What are the steps?
Begins when a sporangium divides asymmetrically to produce the mother cell and the forespore, separated by a septum.
The mother cell engulfs the forespore and a double-membrane bound forespore is formed.
Coat assembly begins just after the initiation of engulfment and continues throughout sporulation.
The peptidoglycan cortex between the inner and outer forespore membranes is assembled during late sporulation.
Finally, the mother cell lyses to release a mature spore.
Who is Robert Koch and What are the 4 postulates of Robert Koch
Robert Koch was a German physician. He became famous for isolating Bacillus anthracis (1877), the tuberculosis bacillus (1882) and vibrio cholerae (1883) and for his development of Koch’s postulates.
Koch’s Postulates:
1. The suspected microorganism is present in every case of the disease absent from health animals.
2. One must isolate and grow the microorganism in pure culture.
3. Injection (infection) of a health host with the microorganism in pure cultures must cause disease.
4. One must be able to isolate the microorganism from the new host.
What are the 4 exceptions to Koch’s Postulates?
Exceptions to Koch’s Postulates:
1. not all pathogens thrive in lab culture,
2. some are species specific,
3. some are synergistic,
4. some become less pathogenic when grown in vitro
What are Koch’s postulates for distinguishing a pathogenic from adventurous microbes?
1- The microbe is regularly found in the lesions of the disease.
2- It can be isolated in a pure culture on artificial media.
3- Inoculation of this culture produces a similar disease in experimental animals.
4- The microbes can be recovered from the lesions in these animals.
Describe the different mechanisms of bactericidal and bacteriostatic antibiotics. Give examples.
Bactericidal antibiotics: Kills bacteria, reduces bacterial load, by affecting bacterial peptidoglycans cell wall.
Examples: penicillin, amoxicillin.
Bacteriostatic antibiotics: Inhibit growth and reproduction of bacteria by affecting bacteria protein production, DNA synthesis, bacterial metabolic activities.
Examples: tetracyclines, erythromycin.
What is the difference between Narrow Spectrum and Broad Spectrum Antibiotics?
Narrow Spectrum Antibiotics: work against a limited group of bacteria and has lower resistance potential. Example: Penicillin G.
Broad Spectrum.
Antibiotics: work against a larger group of bacteria, but can overuse drive resistance. Example: Tetracyclines.
Describe Epidemic / outbreak, cluster, endemic, pandemic and R0 value.
Epidemic or Outbreak: disease occurrence among a population that is in excess of what is expected in a given time and place.
Cluster: group of cases in a specific time and place that might be more than expected.
Endemic: disease or condition present among a population at all times.
Pandemic: a disease or condition that spreads across regions.
R0:
* Basic reproduction number
* How many people each infected person will further infect
* R0 indicates how contagious a disease is
* R0 is an estimate of the speed at which a particular infectious disease can currently spread through a given population.
* The R0 varies, between < 1 if the disease is controlled or not spreading too quickly.
What advantage does spore formation offer bacteria?
To ensure survival in a harsh environment
Highly resistant to heat, chemicals and radiation.
