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What is a parasite?
What is Fungi?
What is Bacteria?
What is a Virus?
- 1.Eukaryote, uni/multicellular
- 2. Eukaryote, uni/multicellular
- 3. Prokaryote, unicellular DNA with no introns
- 4. Acellular
Under what conditions do opportunistic pathogens causes disease?
- 1. Immunocompromised
- 2. Normal flora in wrong cavity
- 3. inappropriate growth of normal flora
Definition of Infection
- Microorganisms elicit a measurable immune response by the host.
- can have :
- Asymptomatic carrier - no disease over several incubation periods
- Incubatory Carrier- Disease will occur after incubation period.
Definition of infectious dieases
- Organisms that cause tissue damage.
- Convalescent Carrier state- Organisms shed after patient recovers from clinical disease.
Components of Gram Positive Bacteria
- The peptidoglycan layer is thick and exposed to the EXF. It stains Blue.
- It has LTA (lipoteichoic acids) and TA (teichoic acids) that hold the Peptidoglycan membrane together.
Components of Gram Negative Bacteria
- Thin walled Peptidoglycan wall- inbetween membranes. stains pinkHas LPS (lipopolysaccharids) and Porins (pores) in the outer membrane.
- has :
- Lipid A region- is a surface antigen on the gram neg bacteria
- Core polysaccharide- for integrity
- O antigen- is an endotoxin but makes a bad immunogen
Components of an acid fast cell
- Peptidoglycan,mycolic acid,trehalose dimycolate ,Liparabinomannan,Arbinogalactan
- This cell wall resists intracellular killing
Components of Cell Wall Less Bacteria
No peptidoglycan, cannot be stained with gram stain. has a membrane with cholesterol in it.
- Only found in spirochetes.
- Flagellin covered with outer sheath.
- Not mang targets for the immunsystem
- Only on gram negative
- used for adhesion or transport of bacterial material (sex pilli)
- Type 1: a channel
- Type 3: acts like a syringe to inject toxins.
- Around individual cells
- used for adhesion and protection
- Composition: Mucopolysaccharides and Polypeptides (both are poor immunogens)
- Surround populations of cells.
- Used for adhesion and protection
- Composed of Mucopolysaccharides
- Produced when population reaches a cirtain size
- Only formed when cell is in adverse conditions
- coat components are PAMPS
- not formed in humans
- Proteins secreted by bacteria
- Produced by both gram neg and pos
- Three types:
- 1. A-B toxin (B binds, A activity)- neutralized by antibodies
- 2. Membrane Disrupting Toxin (cytolytic)- create a pore- antibodies recognize them
- 3. Superantigens- antibodies recognize
- Structural component of bacteria
- when the cell lyses it releases these. They act as PAMPs and poor immunogens.However, they can cause Toxic shock when at high concentrations.
How does bacteria grow?
- Binary Fission
- Autolysin is secreted to thin the existing cell wall
- regulated by surface to volume retio
What is the bacterial Genome like?
- No nuclear membrane
- single circular, coiled chromosome
- Double stranded DNA
- Require Sigma factors for division,
- And have either Mono or polycistronic mRNA messages
How do bacteria create diversity?
- Antigenic Variation
- Genetic Recombinition
- Gene transfer
- Transformation- transfer of DNA (Gram Negative. cells must be related)
- Conjugation- movement of DNA between two bacteria (sex pili,coded for and mediated by F factor)
- Transduction- transfer genetic material through a virus
- Transposition- movement of transposons between genome plasmid (flanked by inverted repeats)
What is Hfr (High Frequency conjugation)?
when some plasmids get integrated into the host chromosome because they contain insertion sequences.
What is recombination?
- Integration of donor DNA to the recipient chromosome.
- 1. Homogenious: requires long region of homology. Loss of old replaced by new.
- 2. Specific: Requires only a small region of homology,Foreign DNA may be circular or linear to start, No
- loss of genetic material, End result is the sum of the existing genome plus the integrated DNA