Block 2 - Control of Microbial Growth Flashcards
(57 cards)
When microbes are referred to as “ubiquitous”, where can they be found?
everywhere in the environment
What are microbes defined as if they are present at a given place and time and they are undesirable or unwanted?
contaminant
How many Biosafety Levels are there?
The microbes in BSL-4, are considered what?
4
highly infectious exotic microbes and toxins for hich there is no vaccine or effective treatment.
HIV is within what BioSafety Level?
BSL-2
What term means to “kill or remove the microbes”?
sterilization
True or False:
Disinfected implies that the item is sterile.
False; disinfected is NOT synonomous to sterile.
The use of chemical agents on the skin or other living tissue to eliminate or inhibit microorganisms refers to what term?
antisepsis
What is the term for the process of applying mild heat to kill, or significantly reduce the numbers of, microbes which may spoil food or beverage?
pasteurization
Define the terms thermolabile and thermostable.
thermoabile: easily altered, decomposed or destroyed by heat
thermostable: not easily altered, decomposed or destroyed by heat
True or False:
Bacterial endospores are less resistant than enveloped viruses.
False; they are more resistant.
True or False:
Regarding to microbial death, vegetative cells die more rapidly than spores.
True.
If there is damage to the microbial cell wall, what cellular processes are effected?
What is an example of something that can damage a microbial cell wall?
It blocks its synthesis, digests it, or breaks down its surface.
antibiotics / lysozyme / detergent
If there is a disruption to the cytoplasmic membrane, what cellular processes/structures are effected?
What are some examples that can cause a disruption in the cytoplasmic membrane?
The disruption causes loss of membrane integrity and selective permeability.
detergents (surfactants), heat
If the synthesis of proteins and nucleic acids are inhibited, what cellular processes are effected?
It interferes with gene translation, thus preventing protein synthesis.
If the microbial function and structure of its proteins and nucleic acids are altered, what occurs?
What substances alter the function/structure of proteins and nucleic acids?
Altered structure inactivates or denatures functions of enzymes and nucleic acids.
heat, strong organic solves, phenolics, metallic ions, antibiotics
What does the “refrigeration” of a microbe effect?
What does the “freezing” of a microbe effect?
It slows the metabolism of the microbe but does not kill them for both refigeration and freezing.
What can cause cells to lose the selective permeability of their cell membranes?
Heat
Heat can inactivate proteins and nucleic acids by doing what on the molecular level?
breaking their hydrogen bonds thus unfolding proteins and separating double-stranded nucleic acids.
Sterilization depends on:
- __________
- __________
- __________
temperature
duration of heating
humidity
What common sterilizing machine uses steam under pressure (121*C for 15 minutes)?
autoclave
Within the radiation method of physical control of microbes, there are 3 types of radiation used. What are these three types?
ionizing radiation - gamma
ionizing radiation - electron beam radiation
non-ionizing radiation - ultraviolet
Which type of radiation treatment has “low penetrating power”?
non-ionizing radiation - ultraviolet
With regard to membrane micropore filters, what is the membrane made out of?
How does this particular complex system trap microbes?
cellulose acetate and cellulose nitrate
…traps by pore size and chemical affinity to the matrix
HEPA filters have two uses described in the PDF, these two uses are:
air filters for respiratory protection
biological safety cabinet
