What are the differences between a prophage and a provirus?
A prophage is created when bacteriophage DNA becomes incorporated into the bacterial host's DNA (Lysogenic cycle). Once established, virus can remain dormant for long periods. Each time bacterium divides, prophage is copied and becomes part of progeny bacterium. Phage DNA codes for viral proteins to assemble new temperate phages which mature and are released through cell lysis. A provirus is formed by retroviral-infected cells, after reverse transcription occurs, the viral DNA in itself into a..
Cont. with provirus:
..host's chromosome, a provirus that can remain there indefinitely. When infected cells divide, the provirus is replicated along with the rest of the host chromosome and viral information is passed to progeny host cells. Unlike prophages, this provirus cannot be excised from the chromosome.
How can a bacteriophage affect the pathogenicity of a microorganisms?
Toxic effects of some bacteria are caused by the prophages they contain. C.botulinum contains a prophage that codes for production of toxin causing botulism. This Clostridium species would not be pathogenic otherwise.
What is a plasmid?
An extra-chromosomal ring of DNA that's not required for bacterial metabolism.
Explain transformation, transduction, & conjugation & why are these important?
Transformation is a change in an organisms characteristics due to genetic transfer. Transduction is were genetic material is carried by a bacteriophage. Conjugation is gene transfer carrying large amounts of genetic material and requiring direct contact.All these are important for DNA transport. (lateral gene transfer).
Which DNA virus type has the ability to remain latent for long periods of time?
Which virus type requires reverse transcriptase?
Which picornavirusaffects the liver?The gastrointestinal tract? The nose & upper respiratory tract?
Hepatovirus affects the liver, Enterovirus affects the gastrointestinal tract, and Rhinovirus affects the nose and the upper respiratory tract.
What human disease has viroid involvement and how is the viroid involved in the pathogenicity?
The only human disease that has viroid involvement is hepatitis D, the viroid can only infect a cell if both the hepatitis B virus and D viroid are in the cell.
must spend at least some of their life cycle on or in a host.
normally free-living, but can invade a host if necessary.
live in or on other organisms without harming them.
association between two or more organisms
both members of the association benefit.
feed on dead and decaying organic matter.
harbor parasite while it reproduces sexually.
harbor parasite during another developmental stage.
infected organisms that allow transmission to other hosts.
range of hosts in which parasite can live/mature.
agent of transmission
parasite goes through part of its life cycle in this host.
Compare communicable (contagious) infectious disease with non-communicable disease.
Communicable infectious disease can spread from one host to another, non-communicable diseases spread from person to person.
What is pathogenicity?
The capacity to produce disease.
What is virulence?
The intensity of the disease produced.
What is attenuation and why is it important?
Attentuation is the weakening of the virulence of the pathogen. It is important in the production of some vaccines.
What are normal flora, where do they live and how are they acquired?
Normal flora are the normal bacteria that live on the skin of all humans . They are acquired at birth going through the birth canal.
alwayspresent Ex:skin, mucous membranes, conjunctiva, body openings.
present only under certain conditions.
microflora that do not usually cause disease but can do so under certain conditions.
caused by medical personnel.
infection acquired while in the hospital.
What are virulence factors?
Structural or physiological characteristics that improve the chances of host invasion and infection.
Wat's the difference between an exotoxin and endotoxin?
An exotoxin is secreted into the host tissues. Endotoxins are part of the cell wall of gram negative bacteria that is released into the host tissues when the bacteria die or divide... therefore, treatment of gram negative infection with antibiotics coule make the problem worse (due to massive die-off of microbes andrelease of endotoxin).
What is a toxoid?
A toxoid is an altered toxin that loses its ability to cause harm but retains its antigenicity.
Explain the stages of infection.
1. Incubation- no outward signs or symptoms yet,can still spread disease. 2.Prodromal- start of getting sick. 3. Invasive- typical signs/symptoms are present. a. Acme: signs and symptoms reach their peak. 4. Decline 5. Convalescence 6. Recovery
Know the animal-like protists that can cause human disease.
Animal-like protists- Heterotrophic, unicellular (but some are colonial), mostly free-living, but a few are commensals. 1. Mastigophorans- Trypanosomal, Leishmania, Giardia, Trichomonas. 2. Amebozoa- Entamoeba, Dientamoeba, Endolimax, Iodamoeba. 3. Apicomplexans (sporozoans)- Parasitic, immobile,with complex life cycles.
What is mycology? Mycosis?
Mycology is the study of fungus. Mycosis is human fungal disease- can be superficial, subcutaneous or systemic.
What type of parasitic relationship do fungi have with humans?
Importance to humans- facultative parasites (never obligate) and most are saprophytes. Decompossers important in antibiotic production (antibiosis).Used to treat human infection. Metabolic wastes excreted by fungus that are toxic to some other organisms.
Which fungi are most commonly parasitic to humans?
What are the mechanisms of action of various antimicrobial chemicals?
Reactions affect in proteins: denaturation, reactions include hydrolysis, oxidation, and attachment of functional groups or atoms. Reactions involving membranes: affected by chemicals that disrupt lipids. Surfactants: reduce surface tension,making membranes more permeable, alcohols, detergents (wetting agents), quats. Reactions affecting other cell components: disruption of nucleic acids or metabolic pathways; good method to use on viruses. Reactions affecting viruses: requires inactivation by d
Why should alcohol be used in a dilute solution?
They help increase the concentration and increasing the concentration increases the effects of most antimicrobial chemicals.
What is a wetting agent?
Some detergents that disrupt the cell membrane are used with other compounds to increase their penetration.
How do quats work?
Denature proteins and disrupt membranes.
What is the preferred method of sterilization?
How does autoclaving materials work in sterilization?
The pressure in the autoclave is increased, which also increases the temperature ( the increased pressure allows the temperature to increase even more).
How does osmotic pressure work as a preservation method?
What is chemotheraphy? Anti-microbials? Antibiotics? Chemotherapeutic index?
Chemotherapy is the use of chemical substances to kill pathogenic organisms without injury to the host. Anti-microbials are chemotherapeutic agents used to treat diseases caused by microbes. Chemotherapeuticindexis the maximum tolerable dose/Kg bodyweight divided by minimum does/Kg body weight that will cure the disease. Antibiotics are drugs that kill infectious agents.
Explain narrow spectrum vs.broad spectrum and when should each be used?
Broad spectrum- agents that are effective against a great # of microbes including Gram negative and Gram positive bacteria. ~used in serious illness when the infection is caused by an unknown organism Narrow spectrum- effectiveagainstonly a small # of microbesor even one taxonomic group. ~used when the identity of the organism is known ~decreases chances of antibiotic resistance ~minimizes destruction of the host's normal flora.
Explain some of the side effects of antimicrobial drugs.
Side effects are its toxicity and allergy and disruption of microflora.
What is drug resistance and how is it acquired?
Resistance: when a microorganism initially susceptible to antibiotics is no longer affected by it. ~due to bacteriostatic organisms that are able to evade defenses and antibiotics ~acquired by genetic changes, etc.
What is the major bacterial species that is a problem in nonsicomial infections?
What are the attributes of an ideal antimicrobial drug?
What is the difference between a nonsicomial and an iatrogenic infection?
An iatrogenic infection is caused by medical personnel, a nonsicomial infection is acquired in the hospital.
the study of factors and mechanisms involved with the spread of disease and other health problems within populations.
cause of an infectious disease.
the number of individuals in a population affected by a disease during a specific period in relation to the total number in the population.
the number of deaths due to the disease in a population during a specific period in relation to the total number in the population.
presence of an infectious agent in a population but the severity and number of cases remain too low to present a public health problem.
the disease suddenly has a higher than normal incidence within a population.
What is a carrier? Vector? Vehicle? Zoonoses? Fomaite?
A vector is an agent of transmission. A fomite is a contaminated inanimate object, A vehicle is a non-living carrier of pathogens from its reservoir to the host (ex: Air). Zoonoses are diseases that can be transmitted under natural conditions to humans from other vertebrate animals (rabies in bats, raccoons).
What are the ways that antibodies use to indirectly destroy antigen-antibody complexes?
They are compliment fixation, neutralization, agglutination, and precipitation.
What are the five signs of inflammation and what specific body response causes them?
Redness, heat, swelling, pain, +/- pus. The immunity response. Specifically, redness and heat: caused by increase blood flow to injury, swelling: Due to exudate that seeps from the blood into interstitial spaces, pain: exudate causes pressureon free nerveendings, pus: WBCs have arrived to save the day, and impairment of function (due to swelling) if the area is at a joint.
What is the agranulocyte responsible for specific immunity?
Lymphocyte (T and B cells)
What is the function of the spleen? Lymph nodes?
The spleen contains lymphocyte, macrophages, stores breakdown products of RBC's and the site of fetal RBC production and stores platelets. Lymph nodes are the primary lymphoid organs, They contain two parts the cortex and medulla. Lymph sinuses throughout the node act as the filters, they contain macrophages and they activate the immune system.
What organ is most often the site of first antigen counter in the lymph system?
What is a lymphoid cell type that functions in phagocytosis, and helps to activate specific lymphocytes?
Macrophages and dendritic cells function in phagocytosis. B and T cells help to activate specific lymphocytes.
What are the membranes that are the body's first line of defense against pathogens?
What is compliment? What ways can it help in the immune response? Is compliment part of the adaptive or innate immune response or both?
It "compliments" innate and adaptive immune responses. It is part of both.
What is fever?
Fever is a widespread, systemic response to invasion. Reset of body thermostat due to pyrogens- chemicals secreted by WBCs exposed to pathogens.
What are cytokines, and what type of leukocyte releases them?
Cytokines are chemical mediators in cell-mediated immunity. Cytotoxic and Suppressor T cells release them.
What determines the specific substances that our own immune systems recognize and reacts to?
Environment and genetics
What is the secretory immunoglobulin that helps protect body surfaces?
IgA is the secretory immunoglobulin that helps protect surfaces.
What are natural killer cells? Are they part of the adaptive or innate immune response?
Natural killer cells are large, agranular lymohocytes that act as guardians of the blood and lymph. Part of the innate immune response.
What is the antigen-antibody complex and why is it important?
The hooking of the antibody to the antigen: makes it easier for destruction by phagocytes
Which antibody has multiple binding sites, and why is this important?
IgM has multiple binding sites, important in clumping antigens together.
What is the main way that antibodies destroy cellular antigens?
What is interferon? Interleukins?
Cytokines released by Macrophages and T-cells.
How can active humoral immunity be acquired? Passive?
Active is naturally acquired from infection, requires exposure to pathogen, +/- development of symptoms.Artificially required from vaccinations which contain attenuated or killed pathogens that are still antigenic, usually no symptoms of illness. Passive is artificial and involves harvested antibodies (gamma globulins - IgG) from donor serum.Natural from passive transfer from mom to fetus via placenta and breast milk.
How are endotoxins inactivated by antibodies?
What is the only lymphocyte that can directly destroy pathogens? How does it work?
Cytotoxic T-cells (secrete cytokines such as perforins, granzymes, lymphotoxin, an interferon that have variable effect on the target cells (mostly cell lysis).
What is a viroid?
an infectious RNA particle that reassemble a virus, but is smaller.
Explain +/- sense
(+) sense is were the sequence is from 5' to 3' and is ready to be coded. (-) sense is were the sequence id from 3' to 5' and must be converted to (+) sense before transcription can occur.
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