controlling bacteria growth
No description yet. This curated deck is ready for daily study.
Card preview (24)
where are antiseptics used
on living tissues to reduce or prevent infection
where are disinfectants used
non living surfaces to kill microbes
how do antibacterial chemicals work
Damages cell membranes Denaturing proteins Destroys internal structure of cell
what is moist heat sterilisation
Steam under pressure, effective at denaturing proteins
what is dry heat sterilisation
hot air, longer time, oxidises cell components
what is Radiation sterilisation
uv light damages DNA
what type of radiation is used for used for ionising radiation and what is it used for
gamma rays, penetrates deeply, used for sterilising medical equipment.
what does Filtration sterilisation do and what is it used for
Removes microbes physically from liquids or air using membrane filters. Used for heat-sensitive materials like vaccines or enzymes.
what is Chemical sterilisation
Use of gases or liquid chemicals that disrupt cell function.
what is disinfection
Removal and destruction of microorganisms except bacterial spores as these are resistant used only on non living things
how are chemicals used as disinfectants
Not used as much as they can only be relied on to kill vegetative cells, effectiveness depends on:
what does effectiveness of chemicals as disinfectants depend on
How much organic matter Concentration of active ingredient Organism present
what are antiseptics used for
living tissue
what does a Bacteriostatic substance do
stop growth of bacteria but don’t necessarily kill them. Too diluted or used incorrectly and bacteria growth will continue again
what does a Bactericidal substance do
destroys bacteria, more effective
what is sterilisation
Destruction of microorganisms including bacterial spores
what does dry heat do
Destroys infected materials destroys bacteria by oxidising their protoplasm Hot air is a poor conductor of heat so high temp and long time is needed
what does boiling for 5 mins do
kills vegetative bacteria, not guaranteed to kill endospores
what does boiling at 100° for 10 mins do
destroys non sporing bacteria, after 10 mins sporing will also be destroyed
what can increase the effectiveness of boiling for sterilisation
2% sodium carbonate
what is an autoclave and what does it do
Pressurised vessel Equip treated with water above normal boiling temp, usually 121 degrees for 20 mins Microorganisms are less resistant when wet
what type of radiation is used for sterilisation and what
gamma rays
what is sterilised using radiation
plastic equipment
what wavelength is lethal to bacteria and where is this used
250nm incubation chambers and cabnits