major biological groups of microorganisms
Bacteria, Fungi, Protozoa, Algae, Virus
Study of defense mechanism of body that protects us against infection.
To monitor and control the spread of disease in communities.
Studies the relationships between microbes and crops, with an emphasis on improving yield and combating plant diseases.
Study the use of microbes to produce or harvest large quantities of useful and necessary materials such as vitamins, amino acids, drugs and enzymes.
Genetic Engineering and Recombinant DNA Technology:
Study techniques that deliberately alter the genetic makeup of organisms to induce new compounds, different genetic combination, and even unique organism.
are microorganisms and lack a special cell body called nucleus (bacteria)
Small Size, Unicellular, Simplicity, High growth rate, High Rate of Adaptability
Contains just a single lens and a few working parts.
Composed of 2 magnifying lens, visible light, a condenser (a special lens to converge or focus the rays of light to a single point on the object)
40 = high dry objective lens
100 = oil immersion objective lens
The capacity of an optical system to distinguish or separate two adjacent objects or points from each other.
Fungi, Algae, Protozoans, Heminth worm, animal cells, and plant cells.
Live in extreme environments, (high temperature, high salt, or low PH ).
A. Those that provide motility.
flagella and axial filaments
B. Those that provide attachments.
fimbriae and pilli
The primary function of flagella is to confer motility or self-propulsion that is, the capacity of a cell to swim freely through an aqueous habitat.
Flagellum is composed of three distinct parts:
The filament, the hook, and the basal body (figure).
A type of modified flagellum consist of a long, thin microfibril inserted into a hook
Pilus and fimbria
Pili refer to the long appendages and fimbria refers to short appendages.
They are involved in attachment of the bacteria to the host cells.
Pili are found in gram negative bacteria and also involved in mating process (conjugation).
The bacterial surface and wall are collectively called cell envelope.
This layer develops as a coating of macromolecules to protect the cell and in some cases, help it adhere to its environment. differs among bacteria.
protect bacteria from loss of water and nutrient
This layer is bounded to the cell to some degree, and has a thick, gummy consistency
determine the shape of bacteria and also provide the kind of strong structural support necessary to keep bacterium from bursting or collapsing due to changes in pressure.
cell wall - peptidoglycan
This compound is composed of a repeating framework of long glycon chains with peptide fragments
difference in cell wall
Hans Christian Gram developed a staining technique that delineates two different groups of bacteria (Gram positive and gram negative).
gram positive cell wall
a thick sheet composed of numerous sheets of peptidoglycon and tightly bound acidic polysaccharides (techoic acid and lypotechoic acid).
gram negative cell wall
contains outer membrane,
a thin sheet of peptidoglycan, and an
extensive space between peptidoglycan
and cell membrane
A very thin flexible sheet completely surrounding the cell's internal contents. It is composed of phospholipids, and proteins. Its functions relate to energy extraction, nutrient processing and synthesis. It is an important site of metabolic activities and synthesis of structural macromolecules.
A dense, gelatinous solution inside the bacterial envelope.
composed of water, sugar, amino acid, and salt.
Bacteria do not have a nucleus and their DNA is not enclosed in nuclear membrane, but DNA is aggregated in a dense area of the cell called nucleoid or Chromatin body
Some bacteria contain piece of circular DNA called plasmid which confer protective traits upon bacteria (resisting drug and radiation).
Tiny discrete units, special type of RNA which synthesize protein.
Cell membrane folds up into cytoplasm and increases the internal surface area for membrane function.
Bacteria may concentrate nutrients in granules of varying size, number and content. These stored sources can gradually consume as required.
Endospore or spore is a structure for withstanding hostile condition.
Features of spores, including size, shape, and position in the vegetative cell are useful in identifying some species of bacteria.
0.5 to 3μM
0.2 to 2 μM in diameter and 0.5 to 20 μM in length.
0.2 to 2 μM
0.5 to 50 μM
spherical or ball shape
short rod bacillus
long rod bacillus
single, paired, tetrad, cluster and chain
single, paired, chain, and palisades
by binary fission (Transverse fission) or budding
The basis of population growth is cell division (reproduction) by binary fission.
Time required for a complete fission cycle from parent cell to two daughter cells.
4 phases of bacterial growth
1- Lag phase
2- Exponential (log) growth phase
3- The stationary phase
4- Death phase
control of growth
(1) by killing microorganisms
(2) by inhibiting the growth of microorganisms.
-usually involves the use of physical or chemical agents
agents which kill celss
agents which inhibit the growth of cells
Defines as complete destruction or elimination of all viable organisms in or on an object. There are no degrees of sterilization: an object is either sterile or not.
4. physical removal of cells.
sterilization - heat
most important and widely used. For sterilization always consider type of heat, time of
Application of temperature to ensure destruction of all microorganisms, Endospores of bacteria are considered the most thermoduric of all cells so their destruction guarantees sterility.
burns organisms and physically destroys them, used for needles, inoculating wires, glassware, etc.
100 degrees for 30 min
steam under pressure or pressure cooker - 120 degrees for 15 min
hot air oven - 160degrees/2hours or 170degrees/1hour. Used for glassware, metal, and objects that won't melt.
Usually destroys or distorts nucleic acids. Ultraviolet light is usually used (commonly
used to sterilize the surfaces of objects), although x-rays and microwaves are possibly useful.
Involves the physical removal (exclusion) of all cells in a liquid or gas, especially important to sterilize solutions which would be denatured by heat
chemical and gas
(formaldehyde, glutaraldehyde, ethylene oxide) toxic chemicals kill all forms of life in a specialized gas chamber.
Use of mild heat to reduce the number of microorganisms in a product or food - milk - batch method: 63degrees/30minutes; flash method: 71degrees/15 seconds.
Store perishable foods at low temperatures to slow down the rate of growth and consequent spoilage of the food (e.g. milk).
Low temperatures are not bactericidal. Psychrotrophs, rather than true psychrophiles, are the usual cause of food spoilage in refrigerated foods.
Most microorganisms cannot grow at reduced water activity - removal of water
from product by heat, evaporation, freeze-drying, addition of salt or sugar.
chemicals that kill or inhibit the growth microorganisms including chemical preservatives and antiseptics, as well as drugs used in the treatment should not be taken internally. Examples: mercurials, silver nitrate, iodine solution, alcohols, detergents.
Agents that kill microorganisms, but not necessarily their spores, not safe for
application to living tissues; they are used on inanimate objects such as tables, floors, utensils, etc
examples of disinfectants
chlorine, hypochlorites, chlorine compounds, lye, copper sulfate, quaternary ammonium compounds
antiseptic vs disinfectant
distinguished on the basis of whether they are safe for application to mucous membranes
Cellular chemical change resulting from all chemical reactions and physical working of the cell
Any process that result in the synthesis of cell's molecules or structures- forming larger molecule from smaller molecules.
Breaking down of large molecule and producing energy.
Enzymes facilitate reaction by lowering energy of activation.
Some bacteria obtain metabolic energy by a Substrate Phosphorylation.
Some bacteria obtain metabolic energy by an Oxidative Phosphorylation.
Metabolic energy obtained by Cyclic Phosphorylation (Similar to respiration except that photochemical processes using energy of light).
Total of genetic materials of a cell.
Size of genome varies from 4-5 genes (virus) to more than 10000(human, and plants).
E. coli contains 3000 genes.
Cellular structure composed of a Long, neatly packaged piece of DNA.
Site on the chromosome that provides information for a certain cell function.
DNA replication requires the action of 30 enzymes. The basic steps of replication of DNA are:1- Uncoiling 2- Unzipping 3- Biosynthesis of complementary polynucleotide
Preserving the DNA code and passing it on the daughter cells
inducible operon - regulator
Composed of a gene that code a protein capable of repressing the operon ( a repressor).
inducible operon - control locus
Composed of two genes, the promoter (identified as a palindrome) and the operator ( where transcription of the structural gene initiated).
inducible operon - structural locus
Made up of three genes, each coding for a different enzyme ( Beta galactosidase, permease, and transacetylase) needed to catabolize lactose.
normally in an off mode and does not initiate the enzyme synthesis when the substrate is not present
a bacterial system for amino acid, purine and pyrimidine synthesis. A repressible operon governs anabolism. This operon is normally in the one mode and will be turned off only when this nutrient no longer required
1-Any permanent, inheritable change, in the genetic information of cell is a mutation.
2- An alteration in the nitrogen base sequence of DNA.
A random change in the DNA (mistake in DNA replication)
Effect of natural background radiation (cosmic rays)
Exposure to mutagens(physical or chemical agents that interact with DNA in a destructive manner)
Change in a few bases (addition, removal or substitution).
A change in the code that leads to placement of a different amino acid
This mutation changes a normal codon into a stop codon that does not code for an amino acid and stop the production of protein.
negative effect of mutation
Human gene mutation alteration in a single protein is responsible for more than 400 diseases
positive effect of mutation
One bacterium donates DNA to another bacterium (intermicrobial transfer) and the end product result is a new strain different from both.
provide additional genes for resistance against drugs, metabolic poisons
conjugation (bacterial sex)
Require the attachment of two related species through a pilus and the presence of a special plasmid
Bacterial transfer mediated through the action of a bacterial virus
Transfer of naked DNA and requires no special vehicle. A bacterial nonspecific acceptance of small fragment of a soluble DNA from the surrounding environment, the process is useful for DNA recombinant.
Genes have the distinction of shifting from one side to the other side
prep of dna fragments
Restriction Endonuclease enzymes cut DNA at specific sites
separation of dna fragments
Gel electrophoresis permits DNA fragments to be separated to be on the basis of size. The dye ethidium bromide can bind to DNA, forms a bright fluorescent adduct, and permit the visualization of fragments of DNA in gel
The lowest temperatures that permit a microbe's continued growth and metabolism; below this temperature its activities and growth are genetically inhibited.
It is the highest temperature at which growth and metabolism can proceed. If the temperature arises slightly above maximum, growth will stop, but if it continues to rise beyond this point, the enzymes and nucleic acid will become permanently inactivated and the cells will dye.
It is a small range, intermediate between the minimum and maximum, which promotes the fastest rate of growth and metabolism.
A microorganism that grows optimally below 15°C and is capable of growing at 0°C.
Microorganisms that grow at moderate temperature (20-40°C)
human pathogen temp
Microorganisms that can survive short exposure to high temperature are normally mesophiles (such as spore forming or thick walled microbes).
A microbe that grows optimally at temperatures greater than 45°C.
three atmospheric gases that most influence microbial growth
O2, CO2 and N2.
grow well in the presence of normal atmospheric oxygen and possesses the enzymes (catalase, and desmutase) needed to process toxic oxygen product
capable of growth in the absence and presence of oxygen. Oxygen is not absolutely required for its metabolism. These microorganisms have catalase and dismutase enzymes.
does not grow at normal atmospheric tensions but requires a small amount of oxygen in metabolism.
do not grow in normal atmospheric oxygen, and it lacks the metabolic enzyme system for using oxygen.
A simple cohabitation of organisms
A cooperative relationship between organisms that is beneficial to both members but not obligatory.
One member (A) is neither harmed nor benefited, yet A provides benefits to the other member B.
A harmful interrelationship.
A kind of parasitism when members of a community compete. One microbe secretes antimicrobial chemical that inhibit or destroy another microbe in the same habitat.
Natural substance of Fungus (not made in a lab) produced by Fungi and kills bacteria.
Non- natural substance (viral infection)
Natural substance that is altered in the lab
a. receptor for drug attachment
b. inhibition of biochemical events essential for the parasite but not host
c. microbicidal rather than microbiostatic
d. soluble ( to allow delivery)
e. no resistance
f. remain potent for a long time
g. do not cause allergy
used in bacterial infection
1- Cell wall synthesis
2- Cell membrane function
3- Protein synthesis
4- Nucleic acid synthesis
Spontaneous mutation in a locus that controls susceptibility to given antimicrobial drug
mechanism of drug resistance
1- Synthesis of enzyme for inactivation of drugs
2- Decrease in cell permeability for uptake of drug
3- Change in the number of affinity of the drug receptor sites
4- Modification of an essential metabolic pathway
antimicrobial agents of synthetic origin useful in the treatment of microbial or viral disease
plasmin "r factor"
Plasmids that carry genes for resistance to one or several antimicrobial
Plasmid genes for antimicrobial resistance often control the formation of enzymes capable of destroying the antimicrobial drugs
Microorganism resistance to certain drug may also be resistant to other drugs that share a mechanism of action
1- maintain high level of drug in the issue
2- simultaneously administer tow drugs which are not cross resistance
3- avoid exposure of microorganism to a particularly valuable drug by restricting it use
1- Blocking complete adsorption and /or penetration of the virus into the host cell
2- Blocking the transcription and translation of viral molecules
3- preventing the maturation of viral particles
Microorganisms implanted in a tissue as Colonists
Microorganisms that is rapidly lost
Condition in which pathogenic microorganisms penetrate the host defense and enter the tissues and multiply
Microorganisms that invade the tissue and lead to infection.
malfunction of a tissue or organ caused by microbes or their product
Presence of infectious agent in the tissue with out yet invading it.
Damaged tissues and organs may lead to dysfunction
Damage may be enough to cause death
The large and mixed collection of microbe adapted to the body
sites of normal flora
Skin, Uppder repiratory tract, Alimentary canal, Other opening of urethra, External genitalia, Vagina, External ear canal, External eye ( lid, conjunctiva)
flora of the mouth
Most diverse and adundant of the body.
Cheeks epitherlium, tongue, floor of the mouth, tooth, provide numerous niches for hundres of diffrene species to colonize
process of infection
Microbe enter the body,
cross host barrier,
multiplies in large tissue and
release to exterior ( exit )
portal of entry
Cutaneous and/ or membranous boundary are route for entry. portal entries are the same as anatomicalo site for normal flora
Minimum number of microorgamism required to initatie and infection
microbial invasiveness and toxigenicity
the properties which contribute to ap pathogen capacity to infect and damage host tissue
capable of causing infection and disease in healthy persons with noramal immune defenses.
(secondary pathogen) infect persons whose host defensed ( immunites are compromised
factors that increase opp pathogen
Old age, extreme youth, malnutrition, genetic defect in immunity, acquired effects inimminity ( AIDS), cancer, chemotherapy
Process by which microbe gain a more stable foothold at the portal of entry. Bacteria- Pilli, Fimbria, capsule and adhesive slime. Virus- Specialized receptor. Protozoa- Organelle of locomotion. Parasitic worm- suckers and hocks
dissolve the host defense barrier and promote the spread of microbes to deeper tissues
Digests mucous membranes and is produced by Vibrio cholera
Digest the principal component of skin and hair is produced by dermatohphytic fungi
Digest Fiber of connective tissue and is produced by Clostridium and certain worms
Hyaluroindiase (spreading factor)
Digest ground substance that cements the animal celsls together and is produced by Staphylococci, clostridia, and streptococci
Causes clotting of blodd and plasma and is produced by Staphylocci
Causes dissolving fibrin clot and is produced by streptokinase and staphlokinase