Chapter 9 Flashcards
controlling microbial growth in environment
sterilization def
destruction of all microbes on an object
antisepsis def
removing most organisms from living tissue . especially pathogens
disinfection def
removing most/all microbes from a non-living surface
pasteurization def
heat to destroy pathogens and decrease spoilage microbes in food
-cidal means
to kill
- static means
to inhibit growth
is there a difference btw cidal and static
most show no difference
ideally agents for the control of microbes should be what :
harmless to humans, animals, and objects
inexpensive
fast-acting
stable during storage
Biosafety levels through what
1 to 4
BSL 1 is what
not known to cause disease in healthy humans
BSL 2 is what
associated with human disease
BSL 3 is what
potential for aerosal transmission, serious/fatal
BSL 4 is what
high risk of fatal infections, aerosal transmission in lab
–related agents of unknown risk of transmission
What are some physical methods of microbial control
Heat
Refrigeration and Freezing
Desiccation and Lyophilization
Osmotic Pressure
What are some chemical methods of microbial control
alcohols
halogens
oxidizing agents
radiation
what are the effects of high temp
denature proteins
lower integrity of cytoplasmic membrane and cell wall
disrupt nucleic acids
two types of heating methods
moist heat and dry heat
moist heat does what
autoclave/boil
disinfect,sanitize, sterilize, and pasteurize
denatures proteins and destroys membranes
what type of heat is more effective
moist heat
dry heat does what
for materials that cant withstand moist heat
requires higher temp for a longer time
Refrigeration and Freezing info
lower microbial metabolism/reproduction
some microbes can multiply in refrigerated foods
what is listeria
grows in cold places
desiccation def
drying inhibits growth due to removal of water
lyophilization def
freeze-drying is long-term preservation. it prevents formation of damaging ice crystals
Osmotic Pressure info
high conc of salt or sugar inhibits growth on food
cells in hypertonic solution lose water
even if bacteria survive, they are stressed and have limited replication
what does salt preservation lead to
no spoilage
what inhibits growth on food
high conc of salt or sugar
alcohols info
denature proteins and membranes
swabbbing skin removes most microbes
not effective on endospores
halogens info
damage enzymes by denaturation
many different applications. like chlorine
oxidizing agents info
kill by oxidation of microbial enzymes.
like hydrogen peroxide
radiation type
ionization and nonionization
wavelengths of ionization vs nonionizing
shorter than 1 nm in ionization
longer than 1 nm in non ionization
what does ionization radiation do to ions
disrupt H bonding, covelent bonding, denature DNA
what does nonionizing radiation do
excited electrons to form new covelent bonds
affects 3D structure of proteins and nucleic acids
non ionization radiation ex
UV light
Ionization radiation ex
electron beams, gamma rays, some X-rays
Uv light def
is known as a mutagen
causes damage to the dna
effects of dna mutations of single celled
quick imapct
effects of dna mutations on multicelled
impact over time
3 possible effects of mutation
no effect
advantageous
deleterious
codon def
set of 3 nucleotides that code for an amino acid
types of DNA mutations
point mutations (silent, missense, or nonsense)
frameshift (insertion, deletion)
Photoreactivation def
the process of light dependent repair of UV damage
Photolyase def
enzyme that reparis pyrimide dimers . they are activated by visible light
