Unit 2 Exam Study Guide Micro -3 PDF

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Bio 175 Unit 2 study guide...

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Chapter Six 1. What atomic elements are required for microbial growth? (Top 6) ● Carbon ● Hydrogen ● Nitrogen ● Oxygen ● Phosphorus ● Sulfur 2. Understand the following terms: Name

Definition

Chemotroph

Use inorganic materials for energy and carbon dioxide for carbon

Phototroph

uses sunlight as energy source

lithoautotrophs

microbe which derives energy from reduced compounds of mineral origin

saprobes

feed off of dead and decaying matter; secrete digestive enzymes which breakdown living matter into small molecules so they can then transport it inside their cytoplasm where the microbial cell can then use them.

ectoparasites

live within the host ex. blood stream infection

endoparasites

live on the surface of the host

Intracellular parasites

inside the actual host cells

Obligate parasite

Require something to be able to survive (inside host, oxygen, etc.)

Photoautotroph

uses sunlight for energy and carbon dioxide for carbon

Chemoautotroph

inorganic energy source and carbon dioxide as carbon source

Photoheterotroph

sunlight for energy and organic carbon sources

Chemoheterotroph

chemicals for energy and organic source of carbon

3. Understand osmosis and how water moves across a semi-permeable membrane. Know the effects isotonic, hypertonic, and hypotonic environments have on a bacterial cell. What is plasmolysis and when does it occur? Osmosis: diffusion of water across a semi-permeable membrane. Selectively permeable membrane allows free diffusion of water, but blocks other molecules (salt, sugar). Water will

move from area of lower concentration to an area of h  igher concentration to dilute concentrated area. Plasmolysis: When water leaves the cell. Results in membrane shrinking and morphing.

Hypotonic ●

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Concentration of solutes outside cell is lower than solutes in cytoplasm Water will rush into cell because it is drawn to higher concentration Without a cell wall, too much water will rush into cell=lysis Slightly hypotonic can be favorable for bacterial cells because water keeps cell full and rigid Water vacuole of amoeba moves excess water back out of cell

Isotonic ●

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Solutes equal outside and inside cell, so water moves at equal rates Water will not build up on either side of cell Stable environment

Hypertonic ●

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Concentration of solutes inside cell higher than outside Water will be drawn into environment Plasmolysis Salt will draw water out of microorganisms on food Halobacteria adapted to live in high salt environment, absorb salt to make cytoplasm more isotonic with environment

4. Know the terms osmotic pressure, halophiles, extreme halophiles, and halotolerant. Osmotic pressure: the pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis Halophiles: Salt loving organism Extreme halophiles: Thrives in extremely high concentrations of salt Halotolerant: Can live with salt, but does not need it to survive 5. Temp requirements for growth: a. Know the temp range terms minimum, maximum, and optimum. How would these appear on a growth vs temp graph?

b. Know the characteristics for the following: psychrophiles, psychrotrophs, mesophiles, thermophiles, and extreme-thermophiles. Minimum temperature: lowest temperature that can support even the smallest amount of growth. Maximum temperature: highest temperature that can support microbial growth Optimum Temperature: temperature where species survive/grow best. This is where the highest growth rate occurs.

Psychrophiles

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Live in the coldest temperatures Reproduce at just a little above freezing Once at 10-15 degrees celsius they can no longer grow Rarely pathogenic due to location

Psychrotrophs

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Grow very well at 20-25 degrees celsius Room temp=25 degrees Skin temp=30 degrees Often food pathogens because of room temp Can multiply in fridge Grow poorly at internal body temp (37 degrees) Can cause food poisoning by secreting toxins on food

Mesophiles

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Optimal temperature=37 degrees celsius Grow well in internal body and on skin Most human pathogens are mesophiles Infection causes blood to rush to area → increasing heat → increasing microbial replication

Thermophiles

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Heat-loving 70 degrees celsius Adapted to high temperatures by having heat resistant DNA/enzymes

Extreme-Thermophiles

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Can grow at temperatures above boiling (100 degrees celsius)

6. Oxygen: understand toxin oxygen and how cells deal with this using SOD and catalase. Toxin Oxygen: As oxygen enters cellular reactions, it is transformed into several toxic products: 1. Singlet oxygen 2. Superoxide ion 3. Hydroxyl radicals 4. Hydrogen peroxide

Two Step Process: Needs to have a way to deal with toxic oxygen products. Do so with presence of enzymes. Superoxide dismutase

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Converts toxic oxygen to hydrogen peroxide Hydrogen peroxide is still irritating to cell, but less toxic than toxic oxygen

Catalase (most common)

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Converts hydrogen peroxide to water and free oxygen Peroxidase converts hydrogen peroxide into water (no oxygen released)

*without these enzymes, we know it is a species that cannot grow in presence of oxygen 7. Know what capnophiles are what they need to grow. Capnophiles: Grow best in areas with higher carbon dioxide concentrations than normal. (Neisseria gonorrhea, Streptococcus) 8. Know how oxygen affects the different types of aerobes and anaerobes.

Obligate aerobes

Cannot grow without oxygen

Facultative anaerobes

Like oxygen, but can grow without it (prefer oxygen)

Obligate anaerobes

Cannot tolerate any oxygen

Aerotolerant anaerobes

Can tolerate oxygen, but do not use it

Microaerophiles

Requires small percent of oxygen

9. pH - know where acidophiles and alkaliphiles grow and optimal range for most bacteria. Acidophiles: prefer acidic environments Alkaliphiles: prefer alkaline environments *most organisms prefer areas with a pH of 7 (neutrophiles) 10. Understand the following concepts (know any examples discussed in lecture): symbiosis, mutualism, parasitism, commensalism, biofilms, quorum sensing, synergism, antagonism

Name

Definition

Symbiosis

Where two organisms live together in close partnership

Mutualism

Two organisms benefitting from each other and providing something the other one needs

Parasitism

Two organisms but only one is benefitting while the other is being harmed

Commensalism

Examples ● ● ●

Mutualism Parasitism Commensalism

Two organisms where one is benefitting while the other gains/loses nothing

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S. aureus releases nutrient, so Haemophilus influenzae grows near it

Biofilms

Example of synergism. Beneficial for bacterial survival. May become resistant to antibiotics and disinfectants

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Can grow on teeth, lungs, catheters, pacemakers, respiratory tubing

Quorum sensing

Way bacterial cells can detect chemicals in environment that act as an indicator of population size, triggers cells to produce substances beneficial for community

Synergism

Members cooperate and share nutrients

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Gum disease, dental caries, and some bloodstream infections involve mixed infections of bacteria acting synergistically

Antagonism

An association between free-living species that arises when members of a community compete

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Competing for nutrition or colonization space

11. Understand the process of binary fission and exponential growth. Binary fission: most common method for bacterial reproduction and is asexual. 1. Bacterial cell replicates its chromosome and elongates 2. Two chromosomes migrate to opposite ends and septum forms pinching the cell wall and plasma membrane until 2 cells form 3. One parent cell and two daughter cells 4. One cell with original chromosome and other cell with only a copy Exponential growth: binary fission results in exponential growth because entire population doubles -Doubling is represented as 2^n, where n=generation number 12. Understand a bacterial growth curve and what happens during lag phase, log phase, stationary phase, and death phase.

Lag phase: no increase in bacterial numbers, but metabolic activity is happening Log phase (exponential growth phase): population doubles at every generation Stationary phase: nutrients and space becomes limited. The number of new cells equals the number of dying cells. Death phase: number of dying cells exceeds number of new cells

13. Know the ways that bacterial numbers can be determined, specifically using turbidity, a Hemocytometer, and plating for CFU.

Tubidity ●

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Hemocytometer

Turbidity = cloudiness in liquid media caused by bacterial growth Turbidimeter measures bacterial growth by measuring amount of light passing Less light that passes through = more bacteria

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Plating for CFU

Hemocytometer = glass slide with a geometrical grid etched on it Grid is extremely small and can only be viewed under a microscope Can add a small, known volume of bacterial sample onto slide and then view it Etched grid allows for easier counting

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CFU = colony forming unit (1 single bacterial cell) Can place sample on agar and incubate overnight Each bacterial cell will grow into individual colony that can be counted next day

Chapter Nine 1. What are the possible outcomes from control of microbial growth? “-cidal” ● ● ●

“-static”

Bactericidal - killing of a bacteria cell Fungicidal - killing of a fungus Virucidal - killing of a virus

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Bacteriostatic - preventing growth of bacteria Fungistatic - preventing growth of a fungus

2. Know the following terms: sterilization, disinfection, sanitization, antisepsis/degermination, bactericidal (and “-cidal”), bacteriostatic (and “-static”), sepsis, asepsis, aseptic techniques, antiseptics, disinfectants Sterilization

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Destruction of all viable microorganisms and endospores. 100% removal. For objects, not living tissue.

Disinfection

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Destroys most vegetative microbes, but not endospores Not 100% removal, typically 98-99% For surfaces

Sanitization

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Mechanical removal of microbes to safe levels

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Not 100% removal

Antisepsis/Degerminati on

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To decrease number of microbes on skin For living tissue Ex: hand sanitizer or soap

Bactericidal

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To kill bacteria

Bacteriostatic

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To prevent multiplication of bacteria

“-cidal”

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To kill

“-static”

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Ability to prevent growth/multiplication

Sepsis

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Growth of microbes in blood or tissue

Asepsis

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Prevent entry of infectious agents into sterile tissue

Aseptic Technique

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Derived from asepsis Techniques such as hand washing and sterilization to prevent contamination to patients or ourselves

Antiseptics

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denoting substances that prevent the growth of disease-causing microorganisms.

Disinfectants

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a chemical liquid that destroys bacteria.

3. What factors do we have to consider when looking at the effectiveness of a treatment on microbial death rate? 1. Nature of microbes - gram positive/negative, forming endospores, etc. 2. Material - perishable or can it be placed in an autoclave 3. Contamination levels - low or high level of contamination 4. Agent used - do we use bleach, peroxide, etc. 4. What aspects of a bacterial cell are potential targets for antimicrobial treatment? Understand each of these. Cell Wall

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Block cell wall synthesis → prevents cell from repairing or adding to cell wall

Cell Membrane

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Loss of selective permeability → cannot control what enters or

Cellular Synthetic Processes ●

Agent can disrupt synthesis, which affects cell’s ability to multiply or

Protein Function

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Most proteins need to be folded (right after they are synthesized) Some agents

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Digest cell wall components → holes that impact structural integrity of cell Break down its surface → making it weaker, which makes it susceptible to cell lysis Results in death

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leaves the cell Lysis occurs by water diffusing unregulated Detergents Results in death

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their metabolism Damage to DNA affects replication and can cause mutations Both result in cell death

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are able to unfold/denatur e proteins, which will deactivate their function Once a protein is unfolded, it is almost always impossible to refold Altering folding will also affect active site on protein → loss of function for enzyme

5. Describe the principle and value behind sterilization using an autoclave, the standard autoclave conditions (temperature, pressure, time) Autoclave: ➢ Common method of moist heat ➢ Similar to home pressure cooker ➢ Provide an environment that can increase pressure levels higher than atmospheric pressure → increased temperature previously impossible ➢ Good for killing endospores ➢ Standard conditions: 15 psi, 121 degrees Celsius, 15 minutes 6. What are thermal death time and thermal death point? Thermal Death Time (TDT): shortest length of time required to kill all microbes at a specified temperature Thermal Death Point (TDP): lowest temperature required to kill all microbes in a sample in 10 minutes 7. How do the following methods work to control growth? Are they bactericidal or bacteriostatic? What do they impact? What is the mode of action? You should know these to the level discussed in lecture. Moist Heat

Boiling ● ● ●

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Pasteurization

Bactericidal Causes protein denaturation → death Cannot call sterilization because of open nature of process Most effective for disinfection, not as effective for sterilization 30 minutes = highest level of disinfection

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Autoclave

Bactericidal Does not kill all microbes and does not kill endospores Reduce number of microbes to level to retain liquid’s quality Effective way to disinfect liquid Process of gently heating and cooling until organisms have been killed

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Bactericidal Impact endospores Provide an environment that can increase levels of pressure higher than the atmospheric pressure → increased temp previously impossible Used for sterilization, 15 minutes efficient

Dry Heat Hot Air Sterilization (oven) ● ● ●

Use for heat resistant items Takes hours Destroys endospores

Incineration (flame) ● ● ●

Microbes to ashes and gases Common practice in micro labs Destroys everything

➢ Dry heat dehydrates and denatures proteins + oxidizes cells via burning ➢ Moist heat works faster and at a lower temperature than dry heat ➢ Heat treatment of perishable substances (food products, pharmaceuticals) must rid substance of disease causing agents of microbes Low Temperature Control Desiccation ● ● ●

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Process of drying out → deadly Neisseria gonorrhoeae die just after a few hours of drying Bacillus and Clostridium endospores are viable for thousands of years

Lyophilization ● ● ●

Process of freeze drying using extreme cold + drying techniques Not deadly This preserves microbes by reducing them to a freeze dried powder

Osmotic Pressure Pressure cells undergo when water exerts pressure on the membrane This can be in hypertonic or hypotonic environments Salt curing makes outside environment hypertonic Not sterilization

Filtration ➔ ➔ ➔ ➔ ➔ ➔

Mechanical removal of microbes Not a sterilization process Does not slow growth Physically removes microbes from substance Used for liquids/ gases - must be passed through a filter with extremely small pores For gas, can be an efficient way to remove airborne pathogens Radiation Ionizing radiation

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High energy Very penetrating Damages DNA backbone, causing permanent damage For food, poultry, drugs/medical supplies, mail Gamma, x-rays

Nonionizing radiation ● ● ●

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Uses ultraviolet light Also damages DNA, but in a different manner Does not penetrate well, so it is often used for surface disinfection, not sterilization Can destroy endospores at longer exposures Damage is called Thymine dimer production When two T’s are next to each other, they can be linked by non-ionizing radiation For hospital rooms, schools, food prep areas, dental offices

8. Chemical microbial control methods: Know how the following work to kill/controls growth Halogens (iodine, chlorine)

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Phenols - know Tricolsan

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Halogens impact protein function Iodine - tincture in health care ○ Can be a disinfectant or an antiseptic depending on use ○ Low levels can be used to disinfect water sources, higher levels can be used as a topical antiseptic Chlorine - strictly disinfectant ○ Very effective at destroying bacteria, fungi, viruses, and endospores Disrupt cell walls and membranes

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Chlorhexidine

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Alcohols

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Detergents

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Hydrogen peroxide

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and coagulate proteins Tricolson - antimicrobial product included in a lot of household products ○ Alters hormone regulation in animals, was under FDA investigation ○ Largest concern is with antibiotic resistance ○ FDA recent ban on these in soaps and soap products Used mostly for skin cleansing Antiseptic product that targets some membranes and impacts protein structure Bactericidal for both gram negative/positive, but does not work on endospores Used to prep skin before procedures and as an obstetric antiseptic Mild, low toxicity, rapid action → ideal for common use Most effective at concentrations of 50%-95% Kills by dissolving membranes and coagulating proteins Only ethanol and isopropanol have activity suitable for microbial control Not effective against endospores Work best against vegetative cells Hand sanitizer: 65%-75% QUATS are found in detergents Provide low level of disinfection by disrupting membrane integrity Best used for everyday processes such as hand-washing With addition of deterge...