Microbial Growth Pt.2 Flashcards
(26 cards)
These are acid-vast, which prevents dessication
Mycobacterium
These microbes are resistant to dessication because they are non-living
Viruses
As water leaves the cell, plasma membrane shrinks away from the cell wall. Cell may not die, but usually stops growing (known as wilting in plants)
Plasmolysis
What are the three types of radiation that kill microbes
Ionizing Radiation, Ultraviolet light (Non-ionizing Radiation) and Microwave Radiation
Gamma rays, X-rays, electron beams or higher energy rays; Have short radiations; Used to sterilize disposable medical supplies
Ionizing Radiation
What is a disadvantage of using Ionizing Radiation
It penetrates human tissues; May cause genetic mutations
Damages DNA by producing thymine dimers which cause mutation; Their wavelengths are no longer than 1 nanometer; Used to disinfect operating rooms, nurseries and cafeterias
Ultraviolet light (Non-ionizing Radiation)
What is a disadvantage of using Ultraviolet light
It damages skin, eyes; Does not penetrate paper, glass or cloth
Wavelength ranges from 1 millimeter to 1 meter; Heat is absorbed by water molecules; may kill vegetative cells in most foods; Bacterial endospores are not damaged by this type of radiation; Solid foods are unevenly penetrated b/c water is not evenly distributed in solid foods
Microwave Radiation
Do not sterilize, but reduce microbial population
Disinfectant
Name some qualities of disinfectant
Does not stain the object being disinfected; Acts rapidly; Attacks a wide range of microbes; Readily mixes with water; Does not damage body tissue
What are the different types of disinfectants
Phenols and Phenolics, Halogens- Iodine and Chlorine, Alcohols, Aldehydes, Peroxygens (Oxidizing Agents)
Effective against gram-positive staphylococci and streptococci
Biphenols
Destroys plasma membranes and denature proteins; Advantages: Stable, persist for long times after applied, and remain active in the presence of organic compounds.
Phenols
Compounds with iodine that are slow releasing, takes several minutes to act. Used as skin antiseptic in surgery; Not effective against bacterial endospores.
Iodophors
When mixed in water forms hypochlorous acid:
Cl2 + H2O ——> H+ + Cl- + HOCl ; Used to disinfect drinking water, pools, and sewage; easily inactivated by organic materials
Chlorine
Kill bacteria, fungi, but not endospores or naked viruses; Act by denaturing proteins and disrupting cell membranes; Used to mechanically wipe microbes off skin before injections or blood drawing
Alcohol
Drinking alcohol
Ethanol
Rubbing alcohol
Isopropanol
Irritates mucous membranes, strong odor; Excellent disinfectant
Formaldehyde Gas
Used as an antiseptic; Not good for open wounds because quickly broken
down by catalase present in human cells
Hydrogen Peroxide
Designed to suppress growth of unwanted bacteria and encourage growth of desired microbes.
Selective Medium
Designed to make it easier to distinguish colonies of a desired organism from other colonies growing on same medium plate
Differential Medium
The time required for bacterial population to double through binary fission. Generation times can range from about 10 minutes to several days
Generation Time
