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Microbiology exam 1 2


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What is an emerging disease?
A disease that was unknown until recently (about 30 years)
Name some emerging diseases.
-AIDS, Flesh eating disease, Anthrax, Food poisoning, Toxic Shock Syndrome, and Lyme Disease.
What is the pathogen that causes AIDS?
HIV virus
What is the pathogen that causes Flesh eating disease?
Streptococcus pyogenes
What is the pathogen that causes Anthrax?
Bacillus anthracis
What is the pathogen that causes Food poisoning?
E. coli 0157:H7
Explain how microbes play a postive role in oceans and rivers.
Heterotrophic organisms feed off of bacteria, which are the first link in the food chain.
How do microbes have a positive impact on soil?
They degrade organic matter (Nitrogen and Phosphorus), which helps to keep the soil fertile.
How do microbes aid in the digestion processes of animals?
They use bacteria to break down cellulose (that they could not usually digest) to sugars that they can digest.
Which vitamins to microbes produce?
-Vitamin B
-Vitamin K
Name several chemicals and natural food products that microbes synthesize.
-yogurt, buttermilk, sour cream, yeast, beer, wine, acetone
Microbes produce recombinant gene products. What does this mean? Give one example.
They synthesize human proteins in bacteria such as human insulin.
What did John Hooke observe?
He used a microscope to look at plant cells (the simplest unit of life)
What was Anton van Leeuwenhoek observation?
He used a microscope to observe living microbes. He also believed in spontaneous generation.
What was Francisco Redi's observation?
He found evidence against spontaneous generation. He excluded air and found the microbes were unspoiled.
What did John Needham do with microbes?
He used heat and no exclusion from air, which made him pro spontaneous generation.
What did Spallanzani do with microbes?
He used heat and exclusion from air, making him against spontaneous generation.
What did Lavoisier question?
the role of oxygen
What theory did Virchow formulate?
the biogenesis theory which said that life arises from preexisting life forms.
What did Louis Pasteur do with microbes?
He excluded air which resulted in an inability of colonization. He resolved in favor of biogenesis.
What did Jenner observe?
the diary maids who were getting cow pox were not getting small pox.
What did Jenner design based on his observations?
He designed the first vaccine by taking the fluid from a cow pox blister and purposfully infected people to prevent small pox
Describe virulent and avirulent viruses and give an example of each.
Small pox is a virulent disease which is serious and can be lethal. Cow pox is the avirulent disease which a is very mild form.
What is attenuation?
The microbe that causes a disease mutates in a test tube and loses virulence, making it inable to cause disease.
Explain what heat killing does to a microbe.
When a microbe is heat killed, the outer proteins can be injected to stimulate the immune system.
Explain fractionation.
A microbe (or several) is chopped up and the surface protein is extracted. There are no whole microbes to multiply and cause disease
What did Agostino Bassi use to find the first pathogens associated with disease?
Silk worm disease (fungal)
What did Louis Pasteur use to find the first pathogens associated with disease?
Silk worm disease (protozoan)
What was Lister's observation of microbes and what did this result in?
They cause surgical infection. This observation resulted in the advent of asepsis.
What did Koch contribute to microbiology?
-Anthrax isolation and culture techniques.
-4 postulates to link microbe to disease (still used today)
What did Alexander Fleming discover?
Penicillium notatum, which was the first antibiotic. This inhibited bacterial growth.
Where did Rene Dubos extract antibiotics?
from soil bacteria
What is chemotherapy?
the search for chemical substances with selective toxicity
What is the importance of selective toxictiy?
to make sure the drug is toxic only to the microbe.
Name 3 synthetic drugs and what they were used for.
-Arsenic - Syphilis
-Quinine - Malaria
-Sulfa drugs - Bacterial infections
What are antibiotics? Give 2 examples.
Antimicrobial substances produced by microorganisms such as penicillan and streptomyocin.
What are some concerns associated with the used of these drugs?
-resistance and antiviral agenst.
What is the concern with antibiral agents?
In order to kill a virus, we can't use selectively toxic drugs because they are, for now, toxic to our bodies and cells.
What is immunology?
the study of immunity
What is virology?
the study of viruses
What does recombinant DNA techonlogy have to do with?
Genetics and molecular biology.
what language is used to classify life forms?
latin - usually very descriptive, sometimes just the name of the person who discovered the new species.
Who came up with the current system of classification?
What is the name of the TWO NAME SYSTEM used to name life forms?
binomial nomenclature
What kind of cells are bacteria and archaea?
What kingdoms are classified as Eukaryotic?
Protists, Fungi, Plants, Animals
What is the main difference between prokaryotes and eukaryotes?
Prokaryotes have no nuclear membrane to bind nuclear material, whereas eukaryotes have their genetic material bound by a nuclear membrane
Describe a protozoa
-single celled
-no cell wall
Describe fungi
-cell wall (chitin)
-single or multicelled
-complex CHO
Describe plants
-cell wall (cellulose)
Describe animals
-no cell wall
what are atoms?
the building blocks of living and non-living material
What are molecules?
groups of associated atoms
What is chemistry?
the science of atomic interactions
Describe protons.
- +ve charge
-mass about 2000 X electron
Describe neutrons
-mass is the same as a proton
Describe electrons
- -ve charge
-little mass
What does the atomic charge being balance and neutral imply?
number of protons equals the number of electrons
What is the atomic number?
# of protons
what is the atomic weight?
# of protons plus # of neutrons (~ 2x atomic #)
What are isotopes?
-element family with different atomic weight (different numbers of neutrons)
-stability and abundance may differ
What are electron shells?
3D orbitals around the nucleus containing different numbers of electrons. 1st (2), 2nd and 3rd (8), 4th - 6th (18)
Which shells are filled first?
inner shells
How are stable elements generated?
by having full electron shells. atoms will combine to make full shells if possible.
What is elemental reactivity related to?
the number of unfilled spaces in outermost orbital
what does valence mean?
the number of "gaps" in the outermost shell, an index of combining capacity
What happens to electrons in ionic bonds?
electrons are lost by one atom and gained by another.
What creates negative charge and what is it called?
gain creates an anion (Cl-, S2-)
What creates a positive charge and what is it called?
loss creates a cation (Na+, Ca2+)
What would stop charged ions from attracting and binding?
Other charged molecules coming between them
What is the role of ions?
solubility due to weakness of bond
What occurs with electrons in a covalent bond?
electrons are shared between atoms
How does the strength of covalent bonds relate to those of ionic bonds?
Covalent is a stronger bond
Where are covalent bonds commonly found?
in organic molecules (C and H)
What forms might you find covalent bonds in?
single, double, or triple.
What kind of bond is common in life forms?
hydrogen bonds
What is shared between molecules invovled in a hydrogen bond?
hydrogen atoms (protons)
What atoms, besides hydrogen, are usually involved in hydrogen bonds?
oxygen and nitrogen
Relatively speaking, describe the strength and occurence of hydrogen bonds
weak, but numerous
What type of molecules form many hydrogen bonds?
What is moleculat weight defined as?
The sum of all atomic weights in a molecule
How many molecules does one mole contain?
6.02 x 10^23
What are the 3 main chemical reactions?
describe what happens in a synthesis reaction.
small atoms, ions, or molecules combine to form larger molecules
A + B ---> AB
reactants ---> product
Does a synthesis reaction require energy?
What is formed in a syntheis reaction?
new chemical bonds
what is a syntheis reaction known as?
anabolic reaction
what are synthsis reactions critical in?
building body mass and cell division
What occurs in a decompostion reaction?
energy is release when larger molucules are broken down to smaller molecules.
AB ---> A + B
What happens to the chemical bonds in a decomposition reaction?
chemical bonds are broken
What are decomposition reactions also known as?
catabolic reactions
What are decompostion reactions critical to?
Energy production and tissue breakdown.
What happens in an exchange reaction?
AB + CD ---> AD + BC
What might influence the direction of chemical reactions?
how stable the products or reactants are.
What must occur for molecules to react with one another?
Molecules must collide and they must posess a certain energy level.
What increases the energy level and collision frequency of molecules?
Increase in temperature.
What can be used to increase the temperature and stimulate reaction rate?
-enzymes and catalysts
what is an enzyme?
a protein molecule that assists reactions by acting as catalysts.
What is a catalyst?
material that changes the reaction rate w/o being altered itself. It lowers the energy of activations needed before a reaction can proceed
what purpose to enzyme activities serve in microbiology?
enzyme activities can help us to distinguish between microbes and are used to classify them
what is essential for all life forms?
What does "polar" mean, in regards to water?
the electron (O) has a slight negative charge, and the proton (H) has a slight positive charge
Why does water have a high boiling point?
Because each water moleule forms hydrogen bonds with others causing strong intermolecular forces.
Why is ice less dense than water, causing it to float and provide insulation?
The crystalline bonds in ice are longer than the hydrogen bonds between water molecules.
What does polarity make water a good solvent for?
Ionic molecules
What does polarity allow water molecules to assist in?
Chemical reactions that require an H+ (acidic) or OH- (basic) group.
Why is water a good temperature buffer?
Strong bonds
What is an acid?
H+ ion donor

HCl --> H+ + Cl-
What is a base?
H+ ion acceptor

OH- --> H2O
What is a salt?
a substance that dissociates in water to form ions that are neither bases nor acids
NaCl --> Na+ + Cl-
Name some common acids
stomach acid, lemon juice, grapefruit juice, wine, urine, milk
Name some common bases
seawater, household ammonia and bleach, over cleaner
Describe the pH scale that measures the Acid / Base balance.
<7 = acidic
7 = neutral - pure water
(# protons = # base molecule)
>7 = basic
What common elements can organic compounds contain
(besides C and H)?
O, P, S, N
Describe organic compounds
-Carbon framework
-Associated functional groups with differented properties suited to different biological roles
What is a polymer?
A combination of small organics that have a repeating chain or branch structure.
what are the four main classes of polymers?
-complex carbohydrates
-nucleic acids
What type of polymers are complex carbohydrates?
What type of polymers are lipids?
Fatty acid / glycerol
What type of polymers are proteins?
amino acid
What type of polymers are nucleic acids?
DNA, RNA nucleotide
What type of polymer has no charge and includes fatty acids, steroids, and cholesterol?
What is an important property of lipids and what does it imply?
lipids are non-polar so they tend to repel water and form barriers
name and describe functions of lipids.
-membrane components (phospholipid bilayer)
-hormones, signal molecules
-energy providers (triglycerides, oils - store)
How much of a cell's dry weight to proteins comprise?
What type of bond joins polymers of amino acids?
peptide bonds
List the functions of protein
carrier proteins (hemoglobin), diverse enzyme catalyst, toxins, immune defense (antibodies), movement (actin, flagellin, myosin)
Describe the secondary structure in Amino Acids.
Alpha helix, pleated sheets
Describe the tertiary structure in Amino Acids.
Overall folding of secondary structure
What is the main distinguishing characteristic of the quarternary structure of Amino Acids?
two or more polypeptide chains
which polymer includes sugars, starches and saccarides?
what are the functions of carbohydrates?
-a building block in nucleotide synthesis
-intermediately used for fatty acid and amino acid synthesis
where were nucleic acids first identified?
the nucleus of a eukaryotic cell
what are the units of nucleotides made up of?
one sugar, one organic base, and a phosphate group
What are the DNA subunits of nucleic acids called?
(A, T, C, G)
What are the RNA subunits of nucleic acids called?
(A, U, C, G)
what are the functions of nucleic acids?
storage of genetic instructions (DNA), expressing genetic instructions (mRNA, tRNA, rRNA), role in energy use (ATP)
give the division of a meter and standard notation for a decimeter.
1/10 m
give the division of a meter and standard notation for a centimeter.
1/100 m
give the division of a meter and standard notation for a millimeter.
1/1,000 m
give the division of a meter and standard notation for a micrometer.
1/1,000,000 m
give the division of a meter and standard notation for a nanometer.
1/1,000,000,000 m
what is an illuminator?
the light source on a microscope
what is the condenser of a microscope?
the lens that directs light up through the sample
what is the objective on a microscope?
the magnifying lens close to the sample
what is an ocular?
the magnifying lens in the eyepiece
what is total magnification?
objective x ocular
what is resolution?
the distance between two points that are distinguisable (wave lenght dependent)
what are the types of microscopy?
brightfield, darkfield, phase contrast, differential interference contrast, fluorescence
what type of microscopy uses visible light illumination and is best for stains?
what type of microscopy reflects light off the specimen which is seen against a dark backgroud?
Differences in the way cell regions refract light allow unstained microbes to be viewed alive describes what type of microscopy?
phase contrast
What type of microscopy is more useful for eukaryotic cells and shows variations as differenct brightness levels?
phase contrast
what type of microscopy is similar to phase contrast, but has better resolution, 3D image and color, and uses 2 light beams?
differential interference contrast
Which type of microscopy uses short UV wavelength to excite fluorescent dyes which emit longer wavelength colored light?
Do some fluorochromes have an affinity for specific molecules?
What are the two types of electron microscopy?
transmission (TEM) and scanning (SEM)
What type of lenses are used to focus x-rays with electron microscopy?
what is the resolution used with electron microscopy?
high (2.5 nm)
What does electron microscopy permit the viewing of?
internal cell contents or ultrastructure
What type of electron microscopy uses thin sections stained with heavy metal salts?
Transmission electron microscopy
What type of electron microscopy shows 3D views of specimen surfaces or profiles?
scanning electron microscopy
what is the resolving power of scanning electron microscopy?
around 20 nm
which type of electron microscopy is more detailed?
transmission electron microscopy
Which type of electron microscopy allows samples to be freeze fractured, coated with carbon or gold?
scanning electron microscopy
what does fixing do to microbes?
it attaces the permanently to a surface for viewing
what process fix most microbes?
air drying (15-20 min) and heat.
what is a thin spread of microbes of glass called?
what is the process that colorizes microbes with a dye that emphasizes particular structures called?
describe how a stain works.
the stains for ionic bonds with oppositely charged molecules on cells
what is known as a chromophore?
a colored salt ion
what type of dyes are used to view bacteria and why?
basic dyes because bacteria have a negative surface charge.
ex: Crystal violet, Saffranin, Methylene blue
When are acidic dyes used for bacteria? Give some examples of acidic dyes.
dyes such as Eosin and India Ink are used to Negatively staining bacteria.
what is the method for the gram stain?
-heat fix smear on slide
-apply Crystal Violet
-wash off excess dye (water)
-add Iodine(color intensifyer)
-wash of excess idoine (water)

What are the steps of gram staining after Gram +ve and Gram -ve are both stained purple.
-wash slide with ethanol or alcohol/acetone
-rinse off solvent with water
What is the last step of preparing Gram stain slides and what is the result?
-apply a counterstain of safranin which leaves only the Gram -ve cells pink.
What happens inside the bacterial cell (gram stain)?
Crystal violet and iodine form a CV-I complex of a dark purple color which cannot wash out of the thick cell wall of GRAM +ve
What is the outer covering of Gram negative bacteria?
What does the alcohol wash do to the outer covering of the Gram negative bacteria?
it disrupts the outer covering and the colored CV-I complex is washed out.
Do all bacteria stain using the Gram method?
What type of bacteria does the Gram method work best on?
rapidly dividing bacteria
What does the Gram reactivity of bacteria assist in?
The treatment of disease
What are Gram positive bacteria usually killed by?
Penicillin and Sulfa drugs
What type of drugs are Gram negative bacteria more susceptible to and why?
Streptomycin and Tetracycline because they target protein synthesis
How does an ACID-FAST stain work?
It binds preferentially to bacteria with a waxy material in their cell walls.
What genus does the ACID-FAST stain identify?
Mycobacterium, which includes TB and Leprosy
What is a NEGATIVE stain used for?
to look for bacterial capsules (simple stain does not show capsules)
How do the capsules around a bacterium affect antibiotics?
They can affect the ability of the antibiotic to penetrate and kill a bacterial cell
How can NEGATIVE staining be used in conjunction with a simple stain?
neg. stain can provide a halo-like effect around a thick capsule. simple stain will allow ID of bacterium lying within the capsule
What is a distinguishing factor of a virulent bacteria's capsule?
it is thicker.
How is the genetic material stored in a prokaryotic cell?
in a nucleoid. prokaryotes do not have a nucleus.
where is the genetic material of eukaryotes found?
enclosed in a nuclear membrane
What is the difference between eukaryotic and prokaryotic choromosomes?
prokaryotes: circular
eukaryotes: linear
What is the difference between eukaryotic and prokaryotic organelles?
prokaryotes: non membranous
eukaryotes: in cytoplasm
What is the difference between eukaryotic and prokaryotic histones?
Prokaryotes: no histone proteins

Eukaryotes: highly conserved histones, compact DNA
What is the difference between eukaryotic and prokaryotic cell walls?
Prokaryotes: almost all contain peptidoglycan
Eukaryotes: may be present
-chitin - fungi
-cellulose - plants
What is the difference between eukaryotic and prokaryotic reproduction?
-prokaryotes: binary fission, no mitotic spindle
-eukaryotes: mainly sexual, mitotic spindle aids DNA segregation
What is the size of a prokaryotic cell?
2 - 8 micrometers in length
what are the basic shapes of prokaryotes?
-cocci: sphere
-bacilli: rods
what are the subdivisions and names of a cocci shape?
pairs - diplococci
chains - streptococci
groups of four - tetrads
clusters - staphylococci
what are the subdivisions and names of the bacilli shape?
-pairs - diplobacilli
-chains - streptobacilli
-short rods (E. coli) - coccobacilli
What are the subdivisions and names of the spiral shapes?
-curved rods - vibros
-rigid corkscrews - spirilla
-flexible corkscrews - spirochetes
what are other shapes of prokaryotic cells?
-star shapes- stella
-flat squares - haloarcula
Describe the GLYCOCALYX of a prokaryote's cell wall.
The glycocalyx is a sticky polymer outside the cell wall. It is either a polysaccharide or peptide.
What is the firm attachment of the glycocalyx called?
capsule - does not detach
What is the loose attachment of the glycocalyx called?
slime layer - will detach from bacteria
List the functions of the glycocalyx.
escape phagocytosis and attachment to environmental surfaces
list the arrangements of flagella
-single or multiple
-all over the cell
Describe flagella of a prokaryotic cell.
Long filamentous structures that propel bacteria
Name and describe the two types of propulsion of flagella.
-chemotaxis (chemical stimuli) is a tumbling motion.
-phototaxis ("light" stimuli) causes the bacteria to head straight for the light
Describe axial filaments of a prokaryotic cell.
-similar to flagellae in structure and function
What is the main difference between axial filaments and flagella?
axial filaments are found only on Spirochetes
-Treponema pallidum (Syphilis)
-Borrhelia burgdorferi (Lyme Disease)
Describe fimbriae and pili.
-Thin, short, straight hair-like appendages.
-used for attachment only
-few to several hundred
-can be polar or all over cell
What are PILI specifically used for in regards to bacteria?
They join the bacteria in preparation for the transfer of DNA from one bacerial cell to another (conjugation)
What are the functions of the prokaryote's cell wall?
-maintains the cell shape
-can contribute towards disease process
-can be acted upon by antibiotics
What is the main difference between eukaryotic and prokaryotic cell walls?
the prokaryote has a more complex and rigid structure
Describe the prokaryote's gram positive cell wall.
-thicker peptidoglycan layer
-polysccharides in cell wall
-teichoic acids in cell wall
What do the polysaccharides in the cell wall of a prokaryotic gram positive cell do?
they group the bacteria into medically significant subgroups (Mycolic Acid)
What do the terichoic acids in the cell wall of a gram positive prokaryotic cell do?
-protect against cell wall rupture
-antigenic, permit serological classification of bacteria
Why are gram negative prokaryote cell walls negatively charged and what role does that play in phagocytosis?
-neg. charge due to phosphate groups on phospholipids
-evade phagocytosis
What is the purpose of a gram negative cell wall's second outer lipid membrane?
-barrier to some antibiotics
-digestive enzymes
-heavy metals
-bile salts and dyes
What are the protein channels in gram negative cell walls made of and what do these channels allow?
-made of porin proteins
-allow movement of molecules in and out.
Where is there a very thin layer of peptidoglycan in gram negative cell walls?
the periplasmic space
What is contained in a gram negative cell wall's periplasmic space?
a high concentration of degradative enzymes and transport proteins
How do gram negative cells walls acquire antigenicity?
they have no teichoic acids, but the polysaccharides provide antigenicity
what is serology?
the study of antigens
what is the plasma membrane of a prokaryotic cell made up of?
-phospholipids and proteins
-phospholipid bilayer
-embedded proteins
Describe selective permeability
depends on size and charge of molecule trying to pass through. small, uncharged, or polar molecules can readily pass through membrane
What two processes occur in the plasma membrane of a prokaryote?
diffusion and active transport
what does the nucleoid of a prokaryote contain?
the bacterial DNA chromosome
what is the function of a prokaryotic ribosome?
-protein synthesis
-contain protein and RNA components
What are endospores?
-resistant thick walled forms of Bacillus and Clostridium species
-highly dehydrated
-contain dipicolinic acid
What does the "vegetative state" of enospores refer to?
the endospre is metabolically active.

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