Chapter 1
what is microbiology?
the study of life too small to be seen with the naked eye
what is the difference between inorganic and organic compounds?
Inorganic compounds:
Lacks carbon, usually small & structurally simple
Organic compounds:
Always contain carbon & hydrogen and typically structurally complex
how can you improve resolution? (2 reasons)
Immersion oil – keeps light from refracting & offers better resolution
what are the three shapes of bacteria?
Coccus, bacillus (rods), spiral
Carl Woose
Developed 3 domain system based on rDNA sequences.
what are the two basic types of microorganisms and what is their hallmark difference?
Prokaryotes, Eurkaryotes
Hallmark difference: presence of a nucleus in eukaryotes
what are the characteristics of water?
1. High boiling Point
2. High specific heat (excellent temperature buffer)
3. High surface tension
4. Solid (ice) is less dense than liquid form
what is bright-field illumination used for?
For viewing color or stained specimen
what anatomy of the bacterial cell are found in all bacteria?
plasma membrane
cytoplasm
ribosomes
nucleoid containing DNA
Rudolf Virchow
Hypothesized cells arise from preexisting cells –> theory of biogenesis
why are microbes important? Give at least two reasons.
Possible answers:
In recycling of vital elements (C, N, S, P)
As producers (photosynthesis)
As decomposers of organic waste (sewage treatment and recycling of water)
Bioremediation (using microbes to detoxify pollutants)
what is protein denaturation and why does it occur?
def: protein unravels, loses secondary, tertiary and quaternary structure
Due to high temperature, high or low pH, chemicals (alcohols & detergents)
what is the difference between the uses of fluorescence and confocal microscopy?
fluorescence microscopy: detection of pathogenic bacteria within cells and tissues
confocal microscopy: view microbes in 3D
Penicillin was called a "miracle drug" because it doesn't harm human cells. Why doesn't it?
We don't have a cell wall or peptidoglycan.
John Tydell
Resolved skepticism of Pasteur's results.
Explained discrepancies.
–> hay infusions had bacterial forms resistant to boiling
who was responsible for demonstrating microbes were present in the air and contaminate sterile solutions? Describe the experiment they used to do so and what conclusion they reached.
Louis Pasteur
Swan-neck flask experiment:
1. Poured beef broth into long-necked flask.
2. Heated neck of flask and bent it into S-shape & boiled broth for several minutes.
3. Microorganisms did not appear in cooled solution, even after long periods.
CONCLUSION: S-shaped or "swan-necked" flasks let air in but kept microbes out
Contain C, H & O + P, N, or S
Phospholipids – amphipathic
– polar head
– non-polar tail
– make up membranes
what are the two different types of electron microscopy?
Transmission Electron Microscopy (TEM): Resolves objects as close as 10 pm & magnifies objects 10,000 to 10,000,000x.
Scanning Electron Microscopy (SEM): useful for looking surface structures & resolution is 10 nm; magnifies 1,000 to 500,000 x.
Compare gram-positive & gram-negative cell walls.
Gram-Positive:
1. Thick peptidoglycan
2. Teichoic acid
3. No outer membrane
4. Thin periplasm
Gram-Negative:
1. Thin peptidoglycan
2. No teichoic acid
3. Outer membrane
4. Thick periplasm
Ignaz Semmelwise
Advocated hand-washing to precent transmission of puerperal fever.
what are the seven types of microbes? List two facts about each.
Bacteria: unicellular, peptidoglycan cell walls, divide by binary fission, some motive via flagella, energy source: organic or inorganic chemicals or photosynthesis
Archaea: unicellular, lack peptidoglycan in cell walls, often live in extreme environments, includes methanogen, extreme halophiles & thermophiles, not known to cause disease
Fungi: chitin cell walls, absorb organic chemicals for energy, unicellular (yeasts), multicellular (mold & mushrooms)
Protozoa: absorbs/ingests organic chemicals, some motile via pseudopods, cilia or flagella, free-living or parasitic, some photosynthetic
Algae: Cellulose cell walls (like plants), found in freshwater, saltwater, and soil, photosynthetic, green, red or brown
Viruses: acellular, consists of DNA or RNA core, protein coat, lipid envelope, obligate intracellular parasites (require host cell to replicate & inert outside living hosts)
Multicellular Animal Parasites: multicellular animals, not strictly microorganisms (microscopic stages in life cycles), ex: tapeworms, nematodes (roundworms)
what are the levels of protein structures and their definitions?
primary structure: polypeptide chain
secondary structure: occurs when amino acid chain folds and coils in regular helix or pleaded sheets
tertiary structure: helix and pleated sheets fold into 3D shape of single peptide sequence
quaternary structure: aggregates of two or more polypeptides
what are the steps to the gram stain procedure?
1. application of crystal violet (purple dye)
2. application of iodine (mordant)
3. alcohol wash (decolorization)
4. application of safranin (counterstain)
Prokaryotes:
– Has one circular chromosome. (DNA not associated w/histones, nucleiod)
– Has no membrane-bound organelles.
– Has cell wall. (bacteria: peptidoglycan & archaea: psuedomurein cell walls)
– Divide by binary fission.
Eukaryotes:
– Has paired, linear chromosomes (DNA associated w/histones, housed in nucleus)
– Has other membrane-bound organelles
– Has polysaccharides cell walls present
– Divide by mitosis
Robert Koch
German physician who was first to show that a specific microbe caused a specific disease (Bacilius anthracis caused anthrax)