They are important to the maintenance of an Ecological Balance on Earth.
a) Marine and fresh water microbes are bases of food chains.
b) Soil microbes recycle chemical elements in the soil
c) Play an important role in photosynthesis
a) Cause disease in Humans (HIV)
b) Disease in Animals (Mad cow)
c) Disease in plants (Agriculture)
Unicellular, no nucleus, prokaryotic, binary fission, peptidoglycan cell walls, for energy use organic, inorganic chemicals or photosynthesis
Prokaryotic, lack peptidoglycan in cell walls, live in extreme environments. Include:
Both are similar in chemical composition and chemical reactions.
Eukaryotes ~ Have membrane bound nucleus, & other organelles.
Prokayotes ~ Lack nucleus and membrane enclosed organelles, Peptidoglycan found in cell wall.
The same pathogen must be present in every case of the disease.
The pathogen must be isolated from the diseased host and grown in pure culture.
The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.
The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.
Redi demonstrated that maggots appear on decaying meat only when flies are able to lay eggs on the meatNeedham claimed that microorganisms could arise spontaneously from heated nutrient broth
Closely related organisms can exchange genes in natural recombination.
Genes can be transferred among unrelated species via laboratory manipulation, called recombinant DNA technology.
Recombinant DNA is DNA that has been artificially manipulated to combine genes from two different source
Inserting a missing gene or replacing a defective one in human cells
Protect fruit from frost damage
Used to produce a number of natural proteins, vaccines, and enzymes
These names are the genus name and specific epithet (species), and both names are printed underlined or italicized. The genus name is always capitalized and is always a noun. The species name is lowercase and is usually an adjective. Because this system gives two names to each organism, the system is called binomial nomenclature.
The study of viruses originated during the Golden Age of Microbiology. Since the development of the electron microscope in the 1940s, microbiologists have been able to observe the structure of viruses in detail, and today much is known about their structure and activity.
Prions are infectious proteins first discovered in the 1980s. Prion diseases, such as CJD and mad cow disease, all involve the degeneration of brain tissue.
Prion diseases are the result of an altered protein; the cause can be a mutation in the normal gene or contact with an altered protein.
Pasteur’s solution to the spoilage problem was to heat the beer and wine just enough to kill most of the bacteria that caused the spoilage. Used to reduce spoilage and kill potentially harmful bacteria in milk as well as in some alcoholic drinks.
Treatment of disease with chemical substances. Two types of chemotherapeutic agents are synthetic drugs (chemically prepared in the laboratory) and antibiotics (substances produced naturally by bacteria and fungi to inhibit the growth of other microorganisms.)
Shows a light silhouette of an organism against a dark background. It is most useful for detecting the presence of extremely small organisms.
Brings direct and reflected or diffracted light rays together (in phase) to form an image of the specimen on the ocular lens. Allows the detailed observation of living organisms.
Accentuates diffraction of the light that passes through a specimen; uses two beams of light. Provides a colored, three-dimensional image of the object being observed. Allows detailed observations of living cells.
Specimens are first stained with fluorochromes and then viewed through a compound microscope by using an ultraviolet light source. Microorganisms appear as bright objects against a dark background. Used primarily in a diagnostic procedure called fluorescent-antibody (FA) technique, or immunofluorescence.
differ from Light Microscopes
Uses a beam of electrons, instead of light. Electromagnets, instead of glass lenses, control focus, illumination, and magnification. Thin sections of organisms can be seen. Magnification: 10,000–100,000×. Resolving power: 2.5 nm.
Three-dimensional views of the surfaces of whole microorganisms can be obtained. Magnification: 1000–10,000×. Resolving power: 20 nm.
Capsule staining provides a contrasting background, so the capsules of these bacteria show up as light areas surrounding the stained cells.
10-6 = 0.000,001
A procedure that results in colorless bacteria against a stained background.
Bacteria that lose the crystal violet color after decolorizing by alcohol; they stain red after treatment with safranin.
is the scattering of light rays as they “touch” a specimen’s edge. The diffracted rays are bent away from the parallel light rays that pass farther from the specimen. When the two sets of light rays– direct rays and reflected or diffracted rays–are brought together, they form an image of the specimen on the ocular lens, containing areas that are relatively light (in phase), through shades of gray, to black.
In most gram-positive bacteria, the cell wall consists of many layers of peptidoglycan, forming a thick, rigid structure. In addition, the cell walls of gram-positive bacteria contain teichoic acids, which consist primarily of an alcohol (such as glycerol or ribitol) and phosphate.
There are two classesof teichoic acids: lipoteichoic acid, which spans the peptidoglycan layer and is linked to the plasma membrane, and wall teichoic acid, which is linked to the peptidoglycan layer.
The cell walls of gram-negative bacteria consist of one or a very few layers of peptidoglycan and an outer membrane. The outer memrane has several specialized functions. It's strong negative charge is an important factor in evading phagocytes. The outer membrane also provides a barrier to certain antibiotics (ex. penicillin), digestive enzymes (lysosomes), detergents, heavy metals, bile salts, and certain dyes
Or inner membrane is a thin structure lying inside the cell wall and enclosing the cytoplasm of the cell. The plasma membrane of prokaryotes consists primarily of phospholipids which are the most abundant chemicals in the membrane, and proteins.
molecules are arranged in two parallel rows, called a lipid bilayer. Each phospholipid molecule contains a polarhead, composed of a phosphate group and glycerol that is hydrophilic (water-loving) and soluble in water, andnonpolar tails, composed of fatty acids that are hydrophobic (water-fearing) and insoluble in wate. The polar heads are on the two surfaces of the lipid bilayer, and the nonpolar tails are in the interior of the bilayer.
A way of describing the dynamic arrangement of phospholipids and proteins comprising the plasma membrane.
include simple diffusion, facilitated diffusion, and osmosis.
The movement of a substance across a plasma membrane from an area of higher concentration to an area of lower concentration, mediated by transporter proteins.
The net movement of solvent molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
outside the cell is a medium whose concentration of solutes islowerthan that inside the cell (hypo means under or less).
Cells with weak cell walls, such as gram-negative bacteria, mayburstor undergo osmotic lysis as a result of excessive water intake
s a medium having a higher concentration of solutes than insidethe cell has (hyper means above or more).
Most bacterial cells placed in a hypertonic solution shrink and collapse or plasmolyze because water leaves the cells by osmosis
the cell uses energy in the form of ATP to move substances across theplasma membrane.
The movement of a substance in active transport is usually from outside to inside.
transport depends on transporter proteins in the plasma membrane.
the substance that crosses the membrane is NOT altered by transport across the membrane
a special form of active transport that occurs exclusively inprokaryotes, the substance is chemically altered during transport across the membrane.
which function as the sites of protein synthesis.
Cells that have high rates of protein synthesis, such as those that are actively growing, have a large number of ribosomes.
Ribosomes are composed of two subunits, each of which consists of protein and a type of RNA called ribosomal RNA (rRNA).
Several antibiotics work by inhibiting protein synthesis on prokaryotic ribosomes.
Material held inside a cell, often consisting of reserve deposits.
Within the cytoplasm of prokaryotic cells are several kinds of reserve deposits, known asinclusions. Cells may accumulate certain nutrients when they are plentiful and use them when the environment is deficient.
known as volutin.
- Volutin represents a reserve of inorganic phosphate (polyphosphate) that can be used in the synthesis of ATP.
- found in algae, fungi, and protozoa, as well as in bacteria
typically consist of glycogen and starch, and their presence can be demonstrated when iodine is applied to the cells.
A common lipid-storage material, one unique to bacteria, is the polymer poly-β-hydroxybutyric acid.
are inclusions that contain the enzyme ribulose 1,5-diphosphate carboxylase.
Photosynthetic bacteria use carbon dioxide as their sole source of carbon and require this enzyme for carbon dioxide fixation. Among the bacteria containing carboxysomes are nitrifying bacteria, cyanobacteria, and thiobacilli
are inclusions of iron oxide (Fe3O4), formed by several gram-negative bacteria such as Magnetospirillum magnetotacticum, that act like magnets.
A resting structure formed inside some bacteria.
- Unique to bacteria, endospores are highly durable dehydrated cells with thick walls and additional layers. They are formed internal to the bacterial cell membrane.
- When released into the environment, they can survive extreme heat, lack of water, and exposure to many toxic chemicals and radiation.
The process of spore and endospore formation; also called sporogenesis.
All synthesis reactions in a living organism; the building of complex organic molecules from simpler ones. Anabolic processes often involve dehydration synthesis reactions (reactions that release water), and they are endergonic (consume more energy than they produce).
For enzymatic reactions, however, elevation beyond a certain temperature (the optimal temperature) drastically reduces the rate of reaction.
The optimal temperature for most disease-producing bacteria in the human body is between 35°C and 40°C.
A change in the molecular structure of a protein, usually making it
Denaturation of a protein. Breakage of the noncovalent bonds (such as hydrogen bonds) that hold the active protein in its three-dimensional shape renders the denatured protein nonfunctional.
Most enzymes have an optimum pH at which their activity is characteristically maximal. Above or below this pH value, enzyme activity, and therefore the reaction rate, decline.
The condition in which the active site on an enzyme is occupied by the substrate or product at all times.
An electron is transferred from molecule A to molecule B. In the process, molecule A is oxidized and molecule B is reduced.
Most microorganisms oxidize carbohydrates as their primary source of cellular energy. Carbohydrate catabolism, the breakdown of carbohydrate molecules to produce energy, is therefore of great importance in cell metabolism. Glucose is the most common carbohydrate energy source used by cells.
roduces ATP and reduces NAD+ to NADH while oxidizing glucose to pyruvic acid. In respiration, the pyruvic acid is converted into the first reactant in Krebs cycle. Glycolosis is the oxidation of glucose to pyruvic acid with the production of some ATP and energy-containing NADH
which produces ATP and reduces NAD+ (and another electron carrier called FADH2) while giving off CO2. The NADH from both processes carries electrons to electron transport chain
1. releases energy from sugars or other organic molecules, such as amino acids, organic acids, purines, and pyrimidines;
2. does not require oxygen (but sometimes can occur in its presence);
3. does not require the use of the Krebs cycle or an electron transport chain;
4. uses an organic molecule as the final electron acceptor;
5. produces only small amounts of ATP because much of the original energy in glucose remains in the chemical bonds of the organic end-products, such as lactic acid or ethanol
An organism that uses carbon dioxide (CO2) as its principal carbon source. An organism that uses an inorganic chemical as an energy source and CO2 as a carbon source; An organism that uses light as its energy source and carbon dioxide (CO2) as its carbon source.
When we talk about microbial growth, we are really referring to the number of cells, not the size of the cells. Microbes that are “growing” are increasing in number, accumulating into colonies of hundreds of thousands of cells, or populations of billions of cells
cellular reproduction is most active during this period; cells begin to divide and enter a period of growth, or logarithmic increase
the growth rate slows, the number of microbial deaths balances the number of new cells, and the population stabilizes
exhaustion of nutrients, accumulation of waste products, and harmful changes in pH may all play a role
Number of generations= log number of cells(end) - log number of cells(beginning)
0.301 (which is the log of 2; 1 cell divides into two).
To calculate the generation of time for a population:
60 min/hr X hours = minutes/generation
number of generations
one of the most important requirements for microbial growth; Carbon is the structural backbone of living matter; it is needed for all the organic compounds that make up a living cell.
other elements are needed by microorganisms for the synthesis of cellular material.
protein synthesis requires considerable amounts of nitrogen as well as some sulfur. The syntheses of DNA and RNA also require nitrogen and some phosphorus, as does the synthesis of ATP.
Microbes that use molecular oxygen (aerobes) produce more energy from nutrients than microbes that do not use oxygen (anaerobes).
An organism that can grow with or without molecular oxygen (O2).
Aerobic bacteria, facultative anaerobes growing aerobically, and aerotolerant anaerobes (discussed shortly) produce SOD, with which they convert the superoxide free radical into molecular oxygen (O2) and hydrogen peroxide (H2O2).
O2– + O2– + 2 H+ → H2O2 + O2
A toxic form of oxygen (OH•) formed in cytoplasm by ionizing radiation and aerobic respiration.
These toxic forms of oxygen are an essential component of one of the body’s most important defenses against pathogens, phagocytes. In the phagolysosome of the phagocytic cell, ingested pathogens are killed by exposure to these toxic form of oxygen.
An organism that grows best in an environment with less molecular oxygen (O2) than is normally found in air.
In complex media, the energy, carbon, nitrogen, and sulfur requirements of the growing microorganisms are primarily provided by protein.
A culture medium designed to suppress the growth of unwanted microorganisms and encourage the growth of desired ones.
For example, bismuth sulfite agar is one medium used to isolate the typhoid bacterium, the gram-negative Salmonella typhi (tī'fē), from feces.
A solid culture medium that makes it easier to distinguish colonies of the desired organism.
Streptococcus pyogenes (pī-äj'en-ēz), the bacterium that causes strep throat, show a clear ring around their colonies where they have lysed the surrounding blood cells.
reflects the number of viable microbes and assumes that each bacterium grows into a single colony; plate counts are reported as number of colony-forming units (CFU).
A plate count may be done by either the pour plate method or the spread plate method
bacteria are retained on the surface of a membrane filter and then transferred to a culture medium to grow and subsequently be counted.
the microbes in a measured volume of a bacterial suspension are counted with the use of a specially designed slide.
is used to determine turbidity by measuring the amount of light that passes through a suspension of cells.
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