Unit2-2 Flashcards
(25 cards)
Who invented the first homemade microscope and observed microbes?
Antonie van Leeuwenhoek.
What are Koch’s postulates used for?
To establish a causal relationship between a microorganism and a disease.
List Koch’s four postulates.
- Microorganism present in all cases of disease.
- Isolated and grown in pure culture.
- Causes disease in a healthy host.
- Re-isolated from newly diseased host.
What is a biofilm?
A surface-coating colony of prokaryotic cells that engage in metabolic cooperation.
What are the three main shapes of bacteria?
Cocci (spherical), Bacilli (rod-shaped), Spirilli (spiral-shaped).
What component is found in bacterial cell walls but not in Archaea?
Peptidoglycan.
What color do Gram-positive bacteria stain?
Purple.
Why are Gram-positive bacteria more susceptible to penicillin?
They have a thick peptidoglycan wall that penicillin targets.
What color do Gram-negative bacteria stain?
Pink.
Why are Gram-negative bacteria often more pathogenic?
They have an outer membrane that protects them and can produce endotoxins.
What is transformation?
Uptake of foreign DNA from the environment.
What is transduction?
Transfer of DNA via bacteriophages.
What is conjugation?
DNA transfer between prokaryotes via a pilus.
What are the three parts of a prokaryotic flagellum?
Filament, hook, and motor.
What are pili used for?
Attachment and DNA transfer during conjugation.
What is binary fission?
Asexual reproduction in prokaryotes.
What are the four major nutritional modes in prokaryotes?
- Photoautotrophs (light + CO₂)
- Chemoautotrophs (chemicals + CO₂)
- Photoheterotrophs (light + organic compounds)
- Chemoheterotrophs (organic compounds for energy + carbon)
What type of nutrition do most pathogens use?
Chemoheterotrophy.
Which domain is more closely related to Eukarya: Bacteria or Archaea?
Archaea.
What makes Archaea membrane lipids unique?
They have ether bonds and may form monolayers with tetraether lipids.
Name three types of extremophiles.
- Halophiles (salt-loving)
- Methanogens (produce methane)
- Hyperthermophiles (heat-loving)
What is the human microbiome?
The collection of all microbes living in and on the human body.
What is the difference between exotoxins and endotoxins?
Exotoxins are secreted; endotoxins are part of the outer membrane of Gram-negative bacteria.
What bacterium is a major concern in hospitals due to antibiotic resistance?
Clostridium difficile (C. diff).
