Intro to Micro Part II
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What type of media is MacConkey Agar (MAC)?
selective and differential
How is MAC Agar selective and how is it
selective and differential
How is a MAC Agar selective and how is it differential?
Selective because it selects Gram - bacteria and differentiates between lactose fermenters and non-lactose fermenters.
Name the selective agents in a MacConkey Agar?
Bile salts and crystal violet.
If the bacteria is a lactose fermenter what color will the colonies turn?
What does Triple Sugar Iron (TSI) help us identify?
TSI helps us identify catabolic activities and shows what sugars are being metabolized
Name the four basic shapes of viruses
- Icosahedral (ex: Poliovirus, Hepatitis A ) honeycomb
- Helical (ex: Tobacco Mosaic Virus) double helix
- Complex (ex: Bacteriophage) Jimmy Neutron
- Bullet (ex: Rabies) a bullet
What is the pH indicator for MacConkey Agar?
What are the two obligate intracellular parasites?
Naked viruses and envelope viruses. Envelope viruses have an envelope bilayer membrane which make them more virulent.
How does a virus obtain an envelope?
A virus coats on your cell membrane and uses the lipid bilayer membrane as its own to protect itself from the environment as well as disguise it from your antibodies.
Virus vs. Virion
Techniqualy a Virus is inside yourself and a virion is outside your body.
Spikes on a naked or enveloped virus are made up of what and function to do what?
protein structures that allow the virus to attach to the cell.
Why would you chose ether or chloroform as treatment for a virus?
Ether and chloroform are solvents so they will remove a viruses envelope if it is there.
Solvents break down lipids
What happens if you add ether or chloroform to a flower contracted with a naked virus?
The flower will die because it had no pathogenic envelope
What are the classifications for viruses?
- Nucleic Acid
- Envelope or Naked
- Host range
- Host specificity
- Burst size
What does the term host range mean?
Host range is looking for how many different species a virus will infect. Usually talk about them being narrow(1-4) HIV or broad (> 4) Influenza.
Host specificity is the cell type: what are those three types?
Ebola virus will give you
(always add virus onto the disease or "-ridae"
What is an oncovirus?
A virus that can cause cancer. They inject their RNA into you causing your cells to morph.
Radiation that kills microorganisms is of two types. What are they?
- Ultra violet radiation
- Ionizing Radiation
Ionizing, destruction of DNA, and Non-ionizing, damage of DNA
Gamma rays, X rays and high electron beams are all examples of ionizing or non ionizing radiation?
What is the principal effect of ionizing radiation?
The ionization of water, which forms highly reactive hydroxyl radicals. These radicals react with organic cellular components, especially DNA
High electron beams have low penetrating power but can sterilize with a few seconds of exposure. What does it sterilize?
Pharmaceuticals, disposable dental and medical supplies, such as syringes. surgical gloves, suturing materials and catheters.
Give an example of non-ionizing radiation
Ultraviolet light (UV radiation)
How does UV radiation effect the cell? And what is the process called?
UV light damages the DNA of exposed cells by causing bonds to form between adjacent pyrimidine bases, usually thymines, in DNA chains (thymine dimers) The process is called frameshift mutation.
The enzyme microbes use to protect themselves against thymine dimers
The main function of thymine dimers is...
to inhibit correct replication of the DNA during reproduction of the cell.
The most effective wavelength for killing microorganisms are ___ and why?
260 nm because this is the wavelength absorbed specifically by cellular DNA
Alcohol is a disinfectant which effectively kills ___ and ___ but not _______ and __________.
Alcohol is a disinfectant which effectively kills bacteria and fungi but not endospores and non envelope viruses.
How is alcohol a disinfectant along skin oils?
Example: ethanol and isopropanol
Alcohol denatures protein and can disrupt membranes and dissolve many lipids including the lipid component on an envelope virus.
How is alcohol an unsatisfactory antiseptic when applied to wounds?
Alcohol causes coagulation of a layer of protein under which bacteria continue to grow.
The recommended optimum concentration of ethanol is ___ but concentrations between __ and ___ seem to kill as well.
The recommended optimum concentration of ethanol is 70% but concentrations between 60% and 95% seem to kill as well.
Why is our ethanol less effective than aqueous solutions (ethanol mixed with water)?
Because denaturation requires water
Surfactants can decrease surface tension among molecules of a liquid. Another name for surfactant is
Good surface-active agents include
- soaps and detergents
- acid anionic sanitizers
- quaternary ammonium compounds (quats)
Give the percentages for how many microbes hypocholorites, peroxides, QUATS, alcohol and other
- Hypocholorites- 53%
- Peroxides- 5%
- QUATS- 9%
- Alcohol- 26%
- Other- 7%
An inanimate object or substance capable of transmitting infectious disease from one individual to another is called ___
How does disinfectant effectiveness depend on the amount of protein-containing material present?
Protein based materials absorb and inactivate some chemical disinfectants
Does chlorine inhibit non-eveloped or enveloped viruses?
True or False: Iodine and chlorine are inactivated in the presence of organic matter?
Chlorhexidine is a ____
Chlorhexidine is a biguanide
The activity of peroxides is greatest against aerobic, anaerobic, or micro anaerobic microbes?
Phenols are especially effective against gram + or gram - bacteria and non-enveloped or enveloped viruses?
gram positive bacteria and enveloped viruses
Quaternary ammonium compounds (Quats) are good surface- active agents because they
disrupt plasma membranes and denature proteins and enzymes
The chemical process of breaking down oily film into tiny droplets is called
Soap and detergents physically remove and chemically affect microbes. How?
Soap emulsifies the oily film on skin/ objects into tiny droplets. Then, together, water and soap lift up the emulsified oil and debris rinsing off the microbes.
How does moist heat kill microorganisms?
Moist heat coagulates proteins(denaturation) which is caused by breakage of the hydrogen bonds that hold the proteins in their three dimensional structure.
Ex: watching an egg white fry
Boiling is a form of moist heat sterilization. Boiling kills
vegetative forms of bacterial pathogens, almost all viruses, and fungi and their spores within 10 minutes
How effective UV radiation is depends on a few things. Such as...
- time of exposure and bacteria species.
- Some bacteria species produce pigments for protection.
Ex: melanin for humans
The equipment used for sterilization by steam under pressure
Autoclaves are used to sterilize
- culture media
- transfusion equipment
Autoclave can take 1 hour or more to sterilize and operate at this psi and temperature
15 psi and 121 C
Autoclaves can kill all microorganisms and endospores except
Filtration removes microbes from
liquids and gasses
Name two types of filters used in sterilization
- High-efficiency particulate air filters (HEPA)
- Membrane filters
High-efficiency particulate air filters (HEPA) are used for microorganisms larger than ___ and lower the number of ___ microbes.
0.3 um in diameter and lower the number of airborne microbes
Membrane filters are useful for bacteria because of the pore size on the filter paper.
0.22 um and 0.45 um
When using a membrane filter why is it best to use 0.22 um pore size?
Most bacteria is in starvation mode which causes the bacteria to shrink. To be on the safe side we use 0.22 um.
Another form of dry heat sterilization is hot-air sterilization. Explain the process.
Items to be sterilized are placed in a dry oven at 170 C.
Does high pressure dehydrate or denature proteins?
True or False: Endospores die from high pressure
False. Endospores are relatively resistant to high pressure
True or False: Osmotic pressure dehydrates bacteria.
True. Osmotic pressure dehydrates bacteria by plasmolysis. Plasmolysis is the process where the plasma membrane is pulled apart from the cell wall causing the bacteria to shrivel up.
How do the chemical agents phenols and phenolics denature proteins?
Phenols and phenolics damage the lipids in the plasma membrane allowing cellular contents to leak.
What gives water its characteristic taste?
What is the difference between hard water and soft water?
Hard water has an appreciable quantity of minerals. Soft water is treated with only one cation, Sodium.
Water is a non-polar or polar solvent?
What is a bacteriophage?
A bacteriophage is a virus that infects bacteria
Where would you find the chemical agent bisphenols?
soap and skin lotions
The chemical agent biguanides is used for inhibiting microbial growth and especially effective against; Gram positive or Gram negative bacteria and naked or enveloped viruses?
- Gram positive and Gram negative and enveloped viruses
How do aldehydes inactivate proteins and enzymes?
Aldehydes cross-link with functional groups such as NH2, COOH, OH
How is garlic a natural antimicrobial chemical?
Garlic is acidic (most virulent microbes are neutraphiles so acid kills them) and has a protein called allicin.
How is cranberry a natural antimicrobial chemical?
Cranberry is acidic, inhibits fimbrae formation and is a diuretic
How is echinacea (purple cone flower) a natural antimicrobial chemical?
Probiotics are beneficial gut bacteria. What do they eat for food?
Prebiotics such as garlic, onion, echinacea, tea tree oil, cranberry are used to support probiotics function.
True or False: DNA pairs are held together primarily through covalent bonds
FALSE: DNA pairs are held together by hydrogen bonds.
True or False: Messenger RNA is formed by (translation) of a gene on the DNA template strand?
A bacteriophage is activated when its tail fiber comes into contact with a bacteria. The bacteriophage then attaches itself to an anchor site on the bacterium and punctures the cell wall and cell membrane. It then injects its DNA and takes over the bacterias reproductive machinery. It creates an enzyme to kill the bacteria. Once bacteria lyses it bursts open with the new bacteriophage babies
Prokaryotes have __ chromosome while eukaryotes may have ___
Prokaryotes have one chromosome which contain entire genome while eukaryotes may divide their genome into many
_____ are non-essential, circular pieces of DNA
Nucleotides are composed of
- 5 carbon sugar
- Phosphate group
- Nitrogenous base
What is genetic recombination?
Genetic recombination refers to the exchange of two DNA molecules resulting in new combinations of genes on the chromosome.
Describe the process of recombination
a chromosome segment enters the cell and aligns with its homologous segment on the bacterial chromosome. The two break at corresponding point, switch fragments and rejoin. Resulting with two recombinant bacteria cells.
The three mechanisms for genetic transfer
What is the genetic transfer mechanism transformation?
Transformation is the uptake of naked DNA from the environment into a living cell
A competent living recipient cell in genetic transfer means
The cell can make changes in the cell wall and cell membrane to allow DNA to enter the selective permeable membrane.
Once DNA enters a living recipient cell the DNA has three fates
- 1. Incorporate DNA into chromosome
- 2. Exist as a plasmid
- 3. Can be lost or "cured"
When do we call microbes promiscuous during the genetic transfer mechanism conjugation?
- Promiscuous is the term we use when bacteria
- conjugates with an unrelated bacteria species. Like how humans can only make
- offspring with another human.
What happens in the genetic transfer mechanism conjugation?
The transfer of genetic material from one cell to another involving cell-to-cell contact.
In conjugation gene transfer F+ means
- An F+ cell means it contains a sex pilus gene on
- the plasmid and has the ability to form a pilus. The DNA can be transferred from the F+ cell through the pilus to the living recipient F-.
Agents that induce mutations are called
True or False: Conjugation gene transfer uses naked DNA from a dead donor.
False. Transformation uses naked DNA from a dead donor. Conjugation involves two living cells.
Who proposed the term virus?
The nucleic acid of a virus is
a. DNA only
b. RNA only
c. Both DNA and RNA
d. Neither DNA or RNA
Neither DNA or RNA
In general RNA viruses multiply (synthesis) in the cells ____ and DNA viruses multiply (synthesis) in the cells ____.
In general RNA viruses multiply in the cells cytoplasm and DNA viruses multiply in the cells nucleus.
Viruses cannot be cultivated in ___
a blood agar
What type of virus replicates and spreads, thus generating regions of cell destructions known as plaques?
A viral capsid is composed of subunits called
Distinguish between enveloped and naked viruses?
- Virus's that possess an additional covering external to the capsid is called an envelope virus.
- Viruses that consist of only a nucleocapsid are considered naked viruses.
True or False: The envelope of an animal virus is derived from the cell wall of its host cell
FALSE: The envelope of an animal virus is derived from the cell membrane of its host cell
Give examples of enveloped viruses
BRS, BVD, Coronavirus, IBR, Leukemia, PI3, Pox, Rabies andStomatitis virus
Give examples of non-enveloped viruses
Bluetongue,Papilloma, Parvo and Rota virus.
Viruses that persist in the (host) cell and cause recurrent disease are called
Discuss the function and structure of viral capsids
A viral capsid is the shell that surrounds the nucleic acid in the central core. The capsid is made up of two different types of protein molecules-Helical and Icosahedral
List in order the multiplication cycles in animal virsus?
Describe absorption, penetration, uncoating, synthesis, assembly and release
- absoprtion- specific attachment
- penetration- entry of viral genome
- uncoating- release of viral genome
- synthesis- new viral products made
- release- causes host cell to lyse
What are the two types of viral capsid?
Helical and Isosahedral
How do enveloped and non-enveloped viruses enter a cell?
enveloped virus (HIV) enters a cell through membrane fusion. Once it has entered the cell it loses its envelope. Non-envelope virus enters a cell through endocytosis. In essence, the virus tricks the cell into thinking that the virus knocking at the door is nothing more than nutrition or harmless goods. A cell, which naturally takes in resources from the environment by attaching goods onto surface receptors and bringing them into the cell, will engulf the virus.The virus will then break out of the vesicle which took it in to get to the cytoplasm (Hep C, polio)
What is a capsule?
A capsule is a virulence factor because it enhance the ability of bacteria to cause disease. Capsules contain water which protects bacteria against desiccation (extreme drying). Capsules also provide protection from eukaryotic cells who will engulf them (phagocytosis)
What is the purpose of Kill it vials and B.stearothermophilus
kill it vials tests the efficacy of an autoclave and sterilizer. They contain spores of B.stearothermophilus. If the sterilization was effective there will be no spore growth
the use of organisms to remove pollutants from environment
What is a attenuated vaccine?
An attenuated vaccine reduces the virulence of a virus
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