Lecture 14- Physical and Chemical methods Flashcards
What is the destruction of all microorganisms on inanimate objects?
What type of method is this?
Sterilization
Physical method
What is the destruction of most microorganisms on inanimate objects?
What type of method is it?
Disinfection
Physical and Chemical method
What is the destruction of most microorganisms on living surfaces?
What type of method is it?
Antiseptic
Chemical method
What are the physical methods of microbial control?
Heating and radiation
Tell if these physical methods are sterilizing:
- Incineration
- Dry oven
- Steam pressure
- Boiling water
- Ionizing radiation
- Non-ionizing radiation
- Incineration= sterilization
- Dry oven= sterilization
- Steam pressure= sterilization
- Boiling water= non-sterilization
- Ionizing radiation= sterilization
- Non-ionizing radiation= non-sterilization
Give the order of resistance (most resistant to least) of these microbes:
- Gram-negative bact.
- Gram-positive bact.
- enveloped viruses
- naked viruses
- prions
- fungi
- bacterial endospores
- Prions
- Bacterial endospores
- Gram-positive bacteria
- Fungi
- Naked viruses
- Gram-positive bacteria
- Enveloped viruses
What are these terms:
- Bactericidal
- Bacteriostatic
- Bactericidal =
Destroys the bacteria
- Bacteriostatic
Prevents growth of bacteria
What are the 4 modes of action, chemicals have against microbes?
- Against bact. cell wall
- Against cytoplasmic membrane
- Against bacterial processes (DNA, RNA)
- Against bacterial proteins
How do agents that work against cell wall work?
What is the result?
- Block cell wall synthesis
- Digest the cell wall
Cell lyses
How do agents that work against the cytoplasmic membrane work?
- What is an example?
Bind lipid bilayer, make it leaky.
- Surfactants are amphiphatic
How do agents that work against bacterial processes work?
- What results?
Bind DNA to prevent transcription/translation
Bind ribosomes to stop peptide bonds from forming
- Can’t make proteins
How do agents that work against bacterial proteins work?
- What results?
Denature proteins (become inactive)
- loss of metabolism
What are the effects of heat and cold on bacteria?
Higher temperatures= bacteriocidal
Colder temps= bacteriostatic
What types of bacteria are most resistant to heat and least resistant?
most resistant= endospores
Least resistant= vegetative cells
How does ionizing radiation work?
What are examples?
Ejects electrons from atoms to form ions.
(Bad for mutations/proteins, changes organelles)
- Gamma and x-rays
