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Microbiology Exam 1
Terms in this set (57)
What are the organisms/entities of study in the field of microbiology?
Prokaryotes, Eukaryotes, Acellular
Who was the first human to publish extensive descriptions of microorganisms?
Antony van Leeuwenhoek
How did Louis Pasteur dismantle the theory of spontaneous generation in bacteria?
Swan necked flask experiment. sterilized nutrient broth by boiling, made swan neck and waited a few days.
Who established microorganisms as the causative agent of infectious disease? How did he do this? What was the result of this body of work?
Robert Koch 1. Diseased material from anthrax infected mouse was injected into healthy mouse - got anthrax. 2. Repeated transfer 20x. 3. Removed spleen from sick mice and cultured in beet broth to isolate spores. 4. Injected spores into healthy mice - got sick with anthrax.
What are some of the advancements that were made possible once microorganisms were identified as the causative agents of infectious disease?
Immunity: vaccines created with other forms of disease, weakened or killed strains
Public Hygiene: sewage disposal, hand washing, use of anaseptics, medical statistics, pasteurization
What are some of the future challenges in battling microorganism? Why are some of these challenges emerging?
Emerging Infections - Lyme disease: moving into formerly wild areas, HIV: Species jump. Mad cow disease: poor agricultural practices. Resurgence of "old" diseases - Tuberculosis: Antibiotic abuse, Whooping cough: choosing not to get children vaccinated, Pneumonia: Aging population.
If you are viewing a specimen through a 60X objective lens on a compound microscope what is the likely total magnification?
What type of lens does a microscope use to produce a magnified image? How does the lens produce a magnified image?
Convex lens, light bends when it enters and leaves lens--> where rays converge you gen an enlarged image
What are some ways to increase contrast in microscopy?
Acidic or Basic, attracted to positive or negative charge of molecule
Uses heat and phenol to drive stain into cell and acid to rinse it all away
Fluorescence-->staining a specific part of cell
1. Add CV, all cells purple
2. Add iodine, all cells purple makes molecules larger "sets stain"
3. Add decolorizer gram positive turns purple
gram negative turns clear from an acetone/ethanol blend
4. Add Safranin Gram (-) turns pink
How can staining aid in the diagnosis of TB and other diseases?
TB has waxy outer lining and requires a lot to hold but once its got the stain it doesn't let go
In general, can viruses be imaged with a light microscope?
No, too small, of wavelength of light is greater than width of virus
What are the various ways infectious disease can be diagnosis?
What are some of the shapes that prokaryotes exist as?
Cocci, Rods, Vibrito, Spirila, Spirochetes, Pleomorphic
Are all bacteria of a single species the exact same shape?
Explain some of the consequences of the small size of bacteria
Have a large SA to volume ratio
extra genomic DNA
tube that shuttles plasmid DNA
What are some of the functions of the plasma membrane?
-communication point-->responds to chemical cues (toxins, nutrients)
-major metabolic site-->electron transport enzymes
What is the basic building block of the plasma membrane?
What are some of the ways that Archaeal plasma membranes are different?
contain hopanoid instead of cholesterol, ether bond instead of ester in glycerol
What are the primary categories of bacterial cell well organization?
Gram Positive, Gram Negative, Mycobacteria, Macoplasms
What are the constituents of bacterial peptidoglycan?
Amino Acid chains and sugars
M=NAM=N-acetyl mutamic acid
How are the sugar chains connected in peptidoglycan?
Sometimes tetrapeptide chains are directly connected, else they are connected via peptido inter bridges.
Describe the organization of a gram positive cell wall
Peptidoglycan cell wall: Many layers of peptidoglycan. Teichoic acid: Stabilize and attaches peptidoglycan to the cell.
Describe the organization of a gram negative cell wall
Periplasm: Fluid filled space, up to 40% of volume, lots of nutrient binding proteins.
Lipopolysaccharide: contain Lipid A, core polysaccharide, O specific polysaccharide.
Porin protein: Lets substances travel in and out of outer membrane.
What are the main components of the outer membrane of a gram negative cell wall
Lipopolysaccharide: Lipid A is toxic to humans because immune system over reacts to it.
Lipoprotein: Anchors outer membrane to cell wall.
Porins: Protein channels in outer membrane that allow solute passage (OmpC = small diameter opening. OmpF = Large diameter opening).
What are some difference between the outer membrane bilayer and the plasma membrane bilayer?
outer membrane needs porins because the outside is hydrophillic and inside is hydrophobic so it needs something to allow passage.
What is the composition of a mycobacterial cell wall? What unique function does this organization impart? How does it contribute to the pathogenicity of these bacteria?
-long chain fatty acid
-wax like consistency
makes it slow growing, resistant to desiccation(drying out), hard to kill
What are the primary functions of the cell wall?
1. Maintains Shape
2. Withstand turgor pressure
Do all bacteria have cell walls?
How do bacteria without cell walls survive?
-have cell membranes
-less turgor pressure inside cell
What are the differences between the Archaeal cell wall and the bacterial cell wall?
Archaea PM-->phospholipid monolayer, phospholipids fused together, VERY stable at high temperatures
What is the bacterial capsule? What are some clinical implications of extensive capsulation of bacteria?
-secreted from cell
-protects against phagocytosis
-allows adherence to surfaces
Virulence Factor--> more severe disease
What are the bacterial homologs to the Eukaryotic cytoskeleton?
What is the function of MreB?
help to determine cell shape (actin homolog)
What is the function of FtsZ?
Cell division (tubulin homolog)
Examples of materials stored in bacterial storage granules (inclusion bodies) What would be the reason for storing these molecules/compounds?
Inorganic Storage (phosphate, sulfur), Organic Storage (glycogen, poly b-hydroxybuterate)-preparation of uncertainty of conditions
gas vacuoles-change buoyancy
magnetosomes-filled with magnetite, align bacteria with magnetic field, help find optimal nutrient levels
What is the function of the bacterial ribosome?
How is the bacterial ribosome different than the Eukaryotic ribosome?
70S weight. Eukaryotic weight have 80S sedimentation rate. This allows for selective drug targeting to bacterial ribosomes to leave human ribosomes alone.
What is the most common form of the bacterial genome?
What is the alternative organization for the bacterial genome?
What is the composition of the bacterial nucleoid?
super coiled, usually circular, single dsDNA
60% genome, 30% RNA, 10% protein
What is a bacterial plasmid?
Extragenomic pieces of DNA, most bacteria have them, contain few genes
What are some different types of plasmids?
Conjugative, Resistance, Virulence, Metabolic
Function of Conjugative Plasmid
allow for swapping of genetic material, creates a pilus between F+ and F- E. Coli
Function of Resistance Plasmids
confer resistance to antibodies
Function of virulence plasmids
contain genes that encode toxic products
Function of metabolic plasmids
allow bacteria to breakdown unusual energy sources
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