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Microbio L7
| Question | Answer |
|---|---|
| Generation time | time to double a population Varies between species Impacted by nutrient availability |
| Growth in Pure Closed Culture 4 Steps | Lag phase Log phase Stationary phase Death phase |
| Lag phase- | Cells adjust to their environment |
| Log phase- | Exponential cell growth |
| Stationary phase- | Numbers of cells dividing = number of cells dying |
| Death phase- | cells die as waste accumulates and nutrients are depleted |
| Prokaryotes must | adapt to their environment Cant move quickly |
| How do prokaryotes adapt to heat? | Adaptations: alter lipid composition of membrane |
| Psychrophiles | live at cold temperatures |
| Mesophiles- | live at normal temperature (best to live in humans!!) |
| Thermophiles- | live at hot temperatures |
| Prokaryotes must | maintain cytoplasmic pH (for protein structure and function) |
| Acidophiles: | pH 1-5 Positive membrane to repel protons |
| Neutralopiles: | pH 5-8 |
| Alkaliphiles: | pH 8011 Acids in membrane to neutralize/attract more protons |
| Growth Conditions: Salt | If too salty, water leaves the cell via osmosis Causes shrinking Plasmolysis |
| Halophiles | grow in high salt |
| Facultative halophiles | grow in normal conditions, but can survive high salt |
| Oxygen readily forms | reactive oxygen species (ROS) |
| 2 ROS | Superoxide and peroxide |
| What do ROS's do? | Degrades proteins and other macromolecules (BAD) |
| Organisms that live in the presence of oxygen must | Use enzymes to “defuse” ROS Without these enzymes, oxygen is deadly |
| Obligate Aerobe | Obligated to live in oxygen air. Organisms that depend on oxygen. They NEED oxygen, actively using it in their metabolic processes |
| Obligate Anaerobe | Can not tolerate oxygen. They don’t use it, and they do not need it. Do not have reactive oxygen species |
| Microaerophile | Use small amounts of oxygen. Too much will kill them. |
| Aerotolerant Anaerobe- | They don’t use oxygen, but it does not kill them |
| Facultative Anaerobe | They use oxygen, but can live with out it |
| Where can pathogens typically be found on this oxygen spectrum? | Pathogens can be anywhere on this spectrum, and it depends on what tissue it is they effect |
| Growth factors | things required to grow |
| Phototropophs | light |
| Chemotrophs | chemicals |
| Autotrophs | make their own food “fix carbons” |
| Heterotrophs | must find their own food |
| Chemoheterotrophs | animals |
| Photoautotrophs | plants |
| Most pathogens are | chemotropics- can’t use light as a resource if they are taking nutrients inside a body They live in a host who are rich in these organic nutrients |
| Complex media | lots of nutrients, but exact concentration/identity unknown |
| Defined media | lots of nutrients, but all identities and concentrations known Tells you exactly whats in the media |
| Differential media: | will change color depending on species being grown |
| Selective media: | only lets certain species/strains grow |
| Sterilization | removing all microbes |
| Disinfection | Reducing the number of microbes (not to zero) Many ways to achieve this (physical and chemical) |
| Using heat on microbes? | Heat denatures membranes and proteins, killing cells Some microbes more heat resistant than others Endospores especially resistant |
| Thermal death point: | minimum temp to kill 100% of microbes in 10 minutes |
| Autoclaves: | use high heat and pressure to sterilize equipment Kills spores as welll!! |
| Boiling: | 5 minutes kill most microbes, but spores remain |
| Dry heat: | Oven, flames |
| Using radiation | Introduces mutations that cause cell death |
| Ionizing: | passes through packaging (x-rays) |
| Non-ionized: | only decontaminates surface (UV) |
| Using filtration | Small pores to capture airborne/liquidborne microbes The smaller the pore, the longer it takes for the gas to flow through and be steralized |
| Germicides: | chemicals that kill/remove microbes |
| Disinfectans: | used on inanimate objects |
| Antiseptics: | on living surfaces (skin) |
| Microbiocidal: | kill microbes |
| Microbiostatic: | prevent growth Generally considered capable of disinfections, not sterilizing (unless in high concentrations) |
| Alcohol | Denatures proteins and lipids Example: Ethanol, isopropanol (rubbing alcohol) 60-90% is best Pro: clean flat surfaces and skin. Dries quickly Con: Flammable, can react with plastic and rubbers |
| Aldehydes | Make proteins and nucleic acids non-functionals Example: Formaldehyde, gluteralhyde Pro: steralize surgical equipment Con: toxic to humans |
| Phenols | Tear apart cell wall and proteins Example: Lysol, some mouthwashes Pro: surface disinfection and non-critical equipment Con: Absorbs by porous surfaces, can irritate skin Must be rinsed off before medical use |
| Halogens | Oxidize proteins and nucleic acids Example: bleach (and chlorines), iodine wipes Chlorine Pro: disinfect surfaces, low amounts in water Chlorine Con: toxic! Inactivated by organics |
| Peroxygens | Kill via ROS Example: hydrogen peroxide, peracetic acid Peroxid Pro: useful to disinfect contact lenses, surfaces, skin Peroxide Con: Inactivated by organic |
| Detergents | Amphipathic molecules that target membranes Example: Sodium laurel sulfate (SLS, soaps) quaternary ammonium compounds (QACs) SLS pro: disinfecting skin and hair SLS con: does little to spores |
Created by:
liladdoyle