Microbiology Midterm/Final Q2 Flashcards
Movement of water when a bacterial cell is isotonic
Isotonic: Equilibrium (solute outside cell= same concentration as inside)
Cell in isotonic solution remains unchanged
Water enters and leaves the cell at the same rate (no net change)
exercising the same osmotic pressure that are within the cell
Movement of water when a bacterial cell is hypertonic
Bacterial Cell in a hypertonic solution= moisture leaves the cell and shrivel up
The solute concentration outside of the bacterial cell is higher than the solute concentration inside of the bacterial cell
Hyper (above or more)
Most bacterial cells placed in a hypertonic solution shrink and collapse or undergo plasmolysis
Movement of water when a bacterial cell is hypotonic
Will implode (solute outside cell= lower than inside cell)
Cell in hypotonic solution= enters the cell and fills
The solute concentration outside of the bacterial cell is lower than the solute concentration inside of the bacterial cell
Hypo (less or under)
Most bacteria live in hypotonic solutions, and swelling is contained by the cell wall
Cells with weak walls may undergo osmotic lysis
Cell may expand and burst; plamoptysis; osmotic lysis
Metabolism
the sum of all the chemical reactions within a living organism
Catabolism
✅destructive phase of metabolism
- furnish the energy needed to drive anabolic reactions
- the reactions are exergonic(produce more energy than they use)
- Catabolic reactions are coupled to ATP synthesis
Anabolism
✅ constructive phase of metabolism
- Anabolic reactions are coupled to ATP breakdown
- reactions are endergonic (require an input of energy)
Enzymes
biological catalysts
enzymes are specific in the kind of substrate that they will catalyze
Format for naming enzymes
Substrate name as the prefix
Suffix usually “ase”
duration of an enzyme
the loss of an enzymes characteristic three dimensional shape
Lock and Key Mechanism
enzyme and the substrate have a specific complementary geometric shapes that fit exactly into one another
Denaturation
- the process of necrosis that includes cellular swelling
✅ changes of the nature of cellular proteins - molecular structure is changed due to: heat, radiation, pH changes, or other mechanisms that destroy or diminish their original properties
Sterilization
removal or destruction of all forms of microbial life; including endospores
Disinfection
destruction of vegetative pathogens; destruction of pathogenic organisms
Disinfectant
The chemical or physical agent would be called a disinfectant
Generally used on inanimate objects or surfaces
Contamination
act of introducing disease or infectious microorganisms into or on normally sterile objects
Germicide
Agents that kill a variety of different types of microorganisms, but not necessarily their spores.
bactericide
Agents that kill bacteria but not necessarily their spores.
Fungicide
agent that destroys a fungus; molds and yeasts
Viricide
Agents that destroys viruses.
Insecticide
Agents that kill insects.
Larvacide
Agents that kill larvae, which are wormlike forms of newly hatched insects.
Fumigation
use of poisonous fumes or gases to destroy living organisms; especially rodents, insects (vermin); may be used to disinfect an entire room
Infestation
invasion by animal parasites/ macroscopic organisms (ie., helminths like tapeworms, roundworms, and flukes)
Bacteriostasis
inhibiting the growth of bacteria
Sepsis
microbial contamination
Antisepsis
- The process of microbial growth being inhibited
- The absence of microbial contamination
- A condition free from germs, infections, or any form of microbial contamination
Methods of microbial control
Scrubbing
Heat
Dry Heat
Cold
Desiccation
Osmotic Pressure
Radiation or Light
Scrubbing
Method of microbial control
Washing hands
Washing inanimate objects or surfaces
Moist Heat
Method of microbial control
- Boiling water
- More effective then dry heat
- Destroys most microorganisms, but may not kill some spores and viruses
Free flowing steam
Method of microbial control
Type of Moist Heat
- 100 degrees Celsius for 30 minutes to kill most vegetative pathogens
- Destroys most microorganisms, but may not kill some spores and viruses
Autoclave
Method of microbial control
Type of Moist Heat
- apparatus for sterilization utilizing steam under pressure
- reliable sterilization technique
Dry Heat
Method of Microbial Control
✅ Direct flaming for sterilization
- Mechanism: oxidation of cellular compounds and enzymes
- reliable sterilization technique
Cold
Method of microbial control
✅ Refrigeration or freezer
✅ Bacteriostatic: enzyme activity diminishes, and only slows microbial growth
Desiccation
Method of microbial control
✅ Absence of water
- Water is required for most chemical metabolic reactions in bacteria
- Microorganisms cannot grow where water is very limited or absent
Osmotic pressure
Method of microbial control
✅ The pressure required to prevent the net flow of water across a semi-permeable membrane.
- Osmotic pressure is high in many embalming fluids, which is one of the reasons that it retards microbial decomposition and decreases the spread of infectious disease from the deceased to the public.
Radiation or light
Method of microbial control
✅ UV light damages the DNA
- Visible light; ROY G BIV (violet is most destructive)
Key factors influencing the action of disinfectants
- Nature of the disinfectant
- Concentration of the disinfectant
- Nature of the material to be disinfected
- Number and kind of microorganisms
- Time of exposure (contact time)
- Temperature during exposure
- pH of the disinfectant
Desirable qualities of an ideal disinfectant
Ability to attack most types of microorganisms
Rapid action
Low toxicity to body tissues
Effective in the presence of organic matter
Stability
Harmless to fabric and metal
readily available and inexpensive
High penetrating power
Disinfectants that may be used in a mortuary setting
Halogens
Hypochlorites (chlorine)
Iodophores (iodine)
Alcohols
Aldehydes
Phenolic compounds
Quaternary ammonium compounds
✅ SURFACE TENSION REDUCERS; Benzylalkonium Chloride
- Also Named: QUATS
- they work their way between microbes and a surface and “lift” the microbes so that they can be removed with the wash water, water spreads more easily over a surface; lipolytic
Halogens
✅ oxidizing agents (alter cellular enzymes, and inhibit protein function)
- Group VII of the Periodic Table
- Halogens are extremely reactive elements because of their electron configuration
Hypochlorites (chlorine)
- Sodium hypochlorite (NaOCl)
- Chlorine is used in the form of sodium hypochlorite in a 5 percent concentration in household bleach
Iodophores (iodine)
✅ Iodine in a detergent or tincture of iodine
- detergent loosens microbes from the skin surface and the iodine kills them
Alcohols
✅ DENATURE proteins; lipolytic
- 70% aqueous solution more effective than a concentrated solution
-may be used as an antiseptic on the skin or as a disinfectant by immersing instruments in it - Mechanism: denature enzymes; and aqueous solutions are more effective than concentrated solutions because the water aids in the denaturation process; also dissolves lipids
Ethyl Alcohol
Type of alcohol
(ethanol; grain alcohol)
usually in a 70 percent solution
Isopropyl alcohol
Type of alcohol
(isopropanol; rubbing alcohol)
Aldehydes
- REDUCING AGENTS; inactivate proteins by forming covalent cross links between proteins
- Very effective antimicrobials
- Mechanism: inactivates proteins by forming covalent cross-links with organic functional groups on proteins; aldehydes react with amino groups (in proteins) and nucleotides, linking them together and changing the structure of the chemical compound
Formalin
Type of Aldehyde
(formaldehyde solution)
37% aqueous solution of formaldehyde gas by weight; 40% by volume
Glutaraldehyde (cold or liquid sterilizer)
Type of Aldehyde
Sporicidal in 3-10 hours
- commonly used as a cold sterilizing agent for surgical instruments
Phenolic compounds
✅ denaturing enzymes; lipolytic
- Phenol (carbolic acid)
- Phenol derivatives are used in mouthwashes, soaps, lotions, toothpastes, many household cleaners
Phenol coefficient
✅ Comparing the effectiveness of a water-soluble disinfectant to the effectiveness of phenol
- Equal to 1 – disinfectant has the same effectiveness as phenol
- Less than 1 – disinfectant is less effective than phenol
- Greater than 1 – disinfectant is more effective than phenol
cresol
Type of Phenolic compound
Lysol
Good surface disinfectants
hexachlorophene
Type of Phenolic compound
Good antiseptic
Normal Flora
microorganisms that establish residence but do not produce disease under normal conditions.
Microbial antagonism:
✅ inhibition of one microorganisms growth (pathogens) by the presence of another (normal flora).
- Normal flora benefit the host by preventing the overgrowth of harmful microorganisms
- mutual opposition or contrary action
- Competing for nutrients and space; Producing toxins; Producing pH changes
Commensalism
Type of Symbiotic Relationship
✅ one organism benefits and the other is unaffected
- commensalism exists when one organism gains some benefit, such as protection or nourishment, and the host is not harmed.