Microbiology

Unit One Review

VOCABULARY

Microorganisms: organisms that are too small to be seen with the unaided eye.

Normal microbiota: microorganisms that are normally found on or in the body and do not cause disease.

Germ: rapidly growing cell Pathogen: microbe that causes disease. Bacteriology: a study of bacteria. Mycology: a study of fungi. Parasitology: the study of protozoa, parasites, and

warms. Immunology: a study of immunity. Virology: the scientific study of viruses.

Biotechnology: the industrial application of microorganisms, cells, or cell components to make a useful product.

Microbial ecology: the study of the relationship between microorganisms and their environment; originated from Beijerinck and Windogradskyi.

Microbial genetics: study of the mechanisms by which microorganisms inherit traits.

Microbial physiology: the study of the metabolism of microbes.

Molecular biology: the science of dealing with DNA and protein synthesis of living organisms.

Genomics: the study of an organisms genes; used to classify a microorganisms.

Bio remediation: bacteria degrade organic matter in sewage. Bacteria also degrade or detoxify pollutants such as oil and mercury.

Genetic engineering: a new technique for biotechnology. Bacteria and fungi can produce a variety of proteins including vaccines and enzymes.

Taxonomy: the science of the classification of organisms. Spontaneous generation: the idea that life could arise

spontaneously from nonliving matter. Biogenesis: the theory that living cells arise only from pre-existing

cells. Probiotic: adding microbes to your diet. Nosocomial diseases: acquired in hospitals; an infection that

develops during the course of a hospital stay and was not present at the time the patient was admitted.

Neonate: newborn Immunocompromised: vulnerable to disease caused by normal

microbiota. Fermentation: the enzymatic degeneration of carbohydrates in

which the final electron acceptor is an organic molecule (contains carbon). For example, ATP is synthesized by phosporylation (adding phosphate) and oxygen it is not required. Fermentation is the process that yeasts use to convert sugars to alcohol in the absence of air.

Pasteurization: the process of mild heating to kill particular spoilage microorganisms or pathogens.

Anaerobic: without oxygen

MICROORGANISMS

Too small to be seen with the unaided eye. Decompose organic wastes. Are producers in the ecosystem by photosynthesis. These

include plants, algae, fungi, and cyanobacteria only. Produce industrial chemicals such as ethanol (a solvent;

solvents dissolve substances) and acetone. Produce fermented foods such as vinegar, cheese, bread,

beer, wine, and other useful products. Produce products used in manufacturing (e.g. cellulose) and

disease treatment (e.g. insulin from E. coli). A few microorganisms are pathogenic (cause disease). Knowledge of microorganisms allows humans to:

Prevent food spoilage Prevent disease Understand aseptic technique to prevent contamination

and medicine, surgery, and in microbiology labs.

THE GERM THEORY OF DISEASE

Louis Pasteur, while he was studying fermentation, found that microorganisms are what cause disease.

KOCH’S POSTULATES

OBSERVE: the same pathogen must be present in every case of the disease.

ISOLATE: the pathogen must be isolated from the diseased host and grown in pure culture.

INOCULATE: the pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.

RE-ISOLATE: the pathogen must be isolated from the inoculated animal and must be shown to be the original organism.

MICROBIOLOGISTS

Aristotle: Spontaneous generation: darkness + dampness + grain = mice. Linnaeus: established a system of scientific nomenclature. Each organism

has two names; genus and specific epithet (species). Janssen: invented the compound microscope Galileo: improved both the microscope and telescope. Van Leeuwenhoek: first observation of life microorganisms in teeth

scrapings, and rain water. Hooke: first observation of cells. Devised cell theory: all living things are

composed of cells. Redi: demonstrated that maggots grew only in the meat in which the flasks

were not covered. Virchow: cells arise from pre-existing cells; the beginning of the biogenesis

(cell) theory. Agostino Bassi: showed that a silkworm disease was caused by a fungus.

Ignaz Semmelwise: advocated midwives to wash their hands when going from one obstetric patient to another to prevent transmission of for puerperal fever.

Pasteur: fermentation, pasteurization processes. Pasteur showed that microbes are in the air, rain, spoiled foods, and cause disease in animals. Discoveries included the relationship between microbes and disease, immunity, and anti-microbial drugs (Germ Theory of disease). His work led to the first vaccine (chicken cholera). He also invented the rabies vaccine. His evidence was proof of biogenesis; led to aseptic technique (by Lister) to prevent contamination in laboratory and medical procedures.

Koch: Koch’s postulates, pure cultures; he proved that a bacterium causes anthrax and provided the experimental steps (Koch’s postulates) to prove that a specific microbe causes a specific disease.

Lister: studied sewage in cattle fields; used phenol for aseptic surgery to disinfect and prevent surgical wound infections after looking at Louis Pasteur’s work.

Jenner: invented the vaccine for small pox: he inoculated a person with the non-deadly cow pox virus. The person became protected from the deadly smallpox virus. He called this protection “immunity”. He then made the first “vacca” (vaccination) for cows. His work began when he saw milkmaids touching cows with lesions on their udders; milkmaids were not contracting smallpox.

Ehrlich: developed first antibiotic drug: Salvarsan, to treat syphilis; coined the term "chemotherapy".

Von Behring: Discovered diptheria antitoxin. Ross: discovered that mosquitoes transmitted malaria Metchnikoff: discovered phagocytosis of white blood cells when he

observed a thorn in a starfish. He began the field of immunology and studied the immune response.

Fleming: discovered the first antibiotic (penicillin). He discovered that Penicillium fungus killed Staphylococcus aureus, when he found a green mold growing on his Petri dish of bacteria.

Chain and Florey: produced penicillin for large-scale manufacture during WWII.

Lancefield: classification of Streptococcus. Griffith: found a “transformation principle” in bacteria, known as DNA today.

Non-virulent streptococci (can’t cause disease) were formed into virulent strains.

Watson and Crick: discovered the structure of the DNA molecule Jacob and Monod: discovered the role of messenger RNA in protein

synthesis. Delbruck and Hershey: discovered the replication mechanism and the

genetic structure of viruses. Tonegawa: antibody genetics Prusiner: discovered the disease-causing protein called a prion (smaller

than a virus).

SELECTED NOBEL PRIZES IN PHYSIOLOGY

1901 Behring diphtheria antitoxin 1902 Ross malaria transmission 1905 Koch TB bacterium 1908 Metchnikoff phagocytosis 1945 Fleming, Chain, Florey penicillin 1952 Waksman streptomycin 1969 Delbruck, Hershey viral replication 1987 Tohegawa antibody genetics 1997 Prusiner prions

MICROSCOPY

Immersion oil: keeps light from bending and allows lens to be refracted.

Resolution: ability of two lenses to distinguish two points.

Parfocal: focused in all lenses. Depth of field: how much of the background is in focus

at the same time that the foreground is in focus. Refractive Index: a measure of the light-bending ability

of a medium Numerical aperture: numerical aperture increases as

depth of field decreases. Resolution power: limits the useful magnification of the

microscope resolving

ESSAY QUESTIONS

Compare and contrast the seven major groups of microbes. Explain the debate over spontaneous generation, name the

scientists involved in the debate, and describe their contributions, stating whether they were for or against the theory of spontaneous generation.

List ten microbiology pioneers that we studied, and describe their contributions to microbiology.

Differentiate among the brightfield, darkfield, dissecting, phase contrast, fluorescence, differential interference contrast, SEM, TEM, and scanning probe types of microscopes, including their purpose, function, or any advantages and disadvantages that we studied.

Differentiate between eukaryotic and prokaryotic cells. Draw a picture of a typical prokaryotic cell and label it. Below your

drawing, pick any five structures you drew and discuss the structure and function of each one.

MICROBES COMPARISON CHART

BACTERIA ProkaryoticPeptidoglycan cell wallsReproduced by binary fissionUses organic and inorganic chemicals or photosynthesis for energyShapes are rod, coccus, spiral

ARCHAEA ProkaryoticLack peptidoglycanLive in extreme environmentsInclude methanogens, extreme Halophiles (love salt), extreme thermophiles (love heat and cold)

FUNGI EukaryotesCell walls have chitinHeterotrophes: use only organic chemicals for energyMolds and mushrooms are multicellular; consist of masses of mycelia, which are composed of filaments hyphae.Yeasts are unicellular

PROTOZOA EukaryotesAbsorb or ingests organic compoundsMay be motile via pseudopods, cilia, or flagella

ALGAE EukaryotesCell wall contain celluloseUses photosynthesis for energyProduces oxygen and organic food for other species

VIRUSES Non-cellular intracellular parasites; lives at the expense of hostContain either DNA or RNA surrounded by a protein coatMay have an envelopeSmallest of all microbesReplicates in living host cellAntibiotics do not work; requires antiviral agents

HELMINTHESANDNEMATODES

EukaryotesHelminthes: parasitic flat worms and tapewormsNematodes: parasitic roundwormsEndoparasites: animals that live inside other animals through fecal contaminationMicroscopic stages of life cycleParasite is in the bite of mosquito or bug; spreads infection in body

MICROBES COMPARISON CHART

Spontaneous Generation Theory

Aristotle thought that the mice grew from the grain and hay, and he coined the term “Spontaneous generation”

Virgil: bees grew from honey and that flies grew from meat.

Redi: maggots in meat were caused by flies laying eggs; they only grew on the meat in which the jars were not covered.

John Needham believed in spontaneous generation; boiled nutrient broth to kill all microbes, put a non-sterile cork in the flask, found that the broth grew microbes.

Louis Pasteur: made a glass flask with an “S” shaped bend in it so that bacteria could not enter into it but air could get in. He placed chicken broth in the flask and boiled it so that it was sterile and observed that there was no bacterial growth in the broth.

COMPARISON OF MICROSCOPES

BRIGHTFIELD Dark objects are visible against a bright background.Light reflected off the specimen does not enter the objective lensNot for looking at live cellsMaximum resolution is 0.2µm and maximum magnification is 2000xStains are used on specimens

DARKFIELD Light objects are visible against dark backgroundUsed for live cells, cilia, flagellaEspecially good for spirochetesUses special condenser with an opaque disc that eliminates all light in the center

PHASE-CONTRAST

No staying requiredAccentuates diffraction of the light that passes through a specimenGood for live cells; good contrastMost sensitive; cilia shows upNot three-dimensional

DIFFERENTIAL INTERFERENCE CONTRAST

Uses two beams of lightShows three dimensionsHas a prism to get different colorsGood for live cells (unstained)Best resolution

COMPARISON OF MICROSCOPES

FLUORESCENCE Uses ultraviolet lightStained cells with fluorescent dye; energizes electrons and creates visible lightNo live cellsQuick diagnosis of TB and syphilis

TRANSMISSION ELECTRON

Get flat imagesHave vacuum pumps to allow electrons to float betterStain with heavy metal saltsShows sections of cell, revealing organellesRequires an ultramicrotomeBest resolution

SCANNING ELECTRON

Surface view onlyNeeds a vacuumNo live cellsThree-dimensional view

SCANNING PROBE

Physical probe scans the specimenRaster scan: image is cut up into pixels and transmitted to computerNot limited by diffractionSlower in acquiring images Maximum image size is smaller

EUKARYOTIC PROKARYOTIC

One circular chromosome, not membrane-bound Paired chromosomes, membrane-bound

No histones Histones present

No organelles Organelles present: Golgi complex, ER, mitochondria, chloroplasts

Peptidoglycan cell walls Polysaccharide cell walls

Reproduce by binary fission Reproduce by mitosis

No true nucleus; no nuclear membrane True nucleus; nuclear membrane; also has nucleoli

Glycocalyx present as capsule or slime layer Present in some cells that lack a cell wall

Plasma membrane has no carbohydrates and lack sterols Plasma membrane has carbohydrates and sterols

No cytoskeleton Has a cytoskeleton

Ribosomes are small (70S) Ribosomes are large (80S)

Prokaryotic Cell Drawing

Structure and Function of Prokaryotic cells

PLASMA MEMBRANECELL WALLGLYCOCALYX

CAPSULE SLIME LAYER

FLAGELLUMSEX PILUSFIMBRAE

PLASMA MEMBRANE

Consists of a phospholipid bilayer, peripheral and integral proteins, and transporter proteins.

Function: selectively permeable; allows for passage of only certain molecules.

Gram negative organisms also have an outer plasma membrane with LPS, which is an antigen and contains a toxin.

CELL WALL

Composed of peptidoglycan, which is a series of two sugars, NAM and NAG, connected with a peptide (or protein) bond.

Function of cell wall: provides rigidity and protection from osmotic lysis.

GLYCOCALYX

A sticky coating external to the cell wall, made of polysaccharide, polypeptide, or both. Made inside of the cell and secreted to the cell surface.

May be either a capsule (organized) or a slime layer (not organized).

Capsule function: to protect from phagocytosis.

Slime layer function: allows for attachment to host.

FLAGELLUM

Made of a protein called flagellin.Consists of a basal body, turning disc,

hook, and filament.Function: ATP is used to turn the discs in

the basal body, which turns the whole flagella to provide movement.

FIMBRAE

Hair-like structures around the cell, made of protein.

Function: Allows bacteria to attach to host. Strains of bacteria that are without fimbrae cannot attach and disease does not occur.

SEX PILUS

Special kind of fimbrae, but longer.Function: allows two cells to attach for

conjugation and transfer of DNA from one cell to another.