Flashcards in Microbiology Deck (87)
What is a microorganism?
They can be in any place on earth
What are microorganisms that live under extreme conditions called?
What is the environment of halophiles?
high salt conditions
What is the environment of Thermophiles?
Temperatures between 60-120 degrees celsius
What is the environment of Cryophiles
Temperatures below 15 degrees
What is the environment of acidophiles?
ph below 3
What is the environment of alkaliphiles?
ph above 9
What is the environment of xerophiles?
extremely dry desiccating conditions
Name the different bacterial morphology shapes?
coccus, bacillus, coccobacillus, fusiform bacillus, vibrio, spirillium, spirochete
What are the different ways that microorganisms can be classified into?
Shapes, Kingdom, Phylum, class, order, family, genus, species, nucleus and other structures, gram negative or positive, size, type of chromosome, diversity, way they move and reproduction.
Name and describe the different external structures of the bacteria.
Flagellum - via a motor (proton motive force), the flagella whips so that the cell can move.
Pili/sex pili/fimbriae - it has a protein at the tips so that it can attach to the host for the bacteria to colonize. It has a plasmid which can be passed on to another cell via replication (DNA double stranded).
Slime layers - excreted by cells is a gelatinous material that attaches loosely to surfaces and allows smooth movement. Formation of biofilms on teeth. Not highly organised.
Capsules - thick polysaccaride layer that strongly attaches to solid surfaces. Protects cell from desiccation and evades the immune system by preventing phagocytosis. Highly organised.
Describe the gram negative bacteria and positive
The gram positive bacteria has peptidoglycan. The peptidoglycan chains are made up of 2 sugars that each have a peptide. The sugars link and the peptide link to make a long chain thus a strong membrane. The peptidoglycan makes up 90% of the cell wall. 1 membrane.
The negative bacteria has the same structure but thinner and is only 5-20% of the cell wall. This means that it can easily lyse but also it has good ability to transport material. 2 membrane (inner phospholipid and outer)
• resistant to heat, cold, drying, and many chemicals
• can survive for many years in soil or dust by being latent
• spores germinate after landing on moist, nutrient- rich surface and develop into vegetative cell.
Endospores can be latent until sufficient nutrient is provided and then it can turn into bacteria.
• important for survival, not reproduction (dormant)
• produced by Bacillus and Clostridium
What are the 4 different ways that bacterial diversity can be classified?
Strain - genetic variation within subtypes
isolate - from which infected individual the bacteria was isolated from
serotype - what specified antibody attaches to it
Pathovar - from which tissue in the host it is found in
What is the imune system?
It is everything that has access and in constant motion and change.
What does the immune system do?
monitors molecular shapes of cells that is non self or self in wrong places (antigens), distinguishes between self and non self. Following this it removes, neutralises, alters or assimilate non self.
protects, assists in recofery from infection or tissue damage. Also maintains a relationship with the external environment
What are the sources of antigens?
Viruses, Bacteria, Parasites, Dust particles or cells from other people (transfusion and transplants).
What does the immune system do with the antigen?
Stores it to form a repertoire of different antigenic shapes for recognition. Anything can be an antigen as long as it is large enough to be recognized.
What is innate immunity?
>First line barrier, not improved by repeated antigen exposure.
>InvolvesLysozyme, complement, acute phase proteins, interferon
Killer (NK) cells
What is adaptive immunity?
>Comes after innate immunity fails. Improved by repeated exposure.
>Involves Lysozyme, complement, acute phase proteins, interferon
> Cells= lymphocytes, monocytes, antigen presenting cells
What are the differences and similarities between innate and adaptive immunity?
Difference is adaptive immunity improves on repeated exposure while innate does not improve. innate is a physical barrier and a first line of defense. The are dependent on each other.
Innate immunity has physical, microbial, cellular and humoral factors. Adaptive immunity has cellular and humoral factors.
How do neutrophils work and when do they work?
Work when surface barriers are breached. They phagocytose foreign material. (ingest and digest). The surface receptors on the phagocytes recognize the common features of the bacteria cell wall. The neutrophils then stick and get activated. At which point the phil folds its membrane around the bacteria ingesting it. Digestive enzymes in the phil digest the bacteria.
what is the complement system?
The system is structured with 20 blood proteins that freely move to protect any surface breaches. They do this by
* changing vascular permeability for neutrophils to move- vasodialate
* attracting phagocytic neurtophils - chemotaxis
* coat the foreign material so that they can be easily phagocytosed - opsonisation
* breach the integrity of bacterial cell walls - lysis
how the complement system work?
The system works to
amplify enzymatic cascade
1. One protein gets activated by adhering to the bacterial cell wall
2. That protein then activates other proteins
3. Those proteins activate other proteins which results in the amplification of enzymatic cascade
How does the immune system recognize antigens?
Receptors. Two types of receptors = cell surface receptors and antibodies.
What happens after antigen recognition?
When the first contact occurs an the immune system responds and builds up tolerance by creating self antigens. The response allows the foreign antigen to be stored up for memory for a future improved response. Secondary contact the immune systems recollects the antibodies it used from the primary contact and forms a better response against the antigen.
What happens in the immune response?
The immune system neutralises, inactivates, destroys, disposes of and or assimilates the material recognized. It produces antibodies to recognize and cytotoxic lymphocytes to kill. The responses aren't immediate.
What is the difference between self and non self?
The immune system learns not to respond to self but can also not respond to non self if the antigen is present before the system has matured. This is called acquired immunological tolerance.
What is the Koch's postulate?
It is the proof of the germ theory.
1. the m.organism must be found in similarly diseased animals. (abandon because germs can be carried asymptomatically so you don't know if the animal has the disease)
2. The germ must be isolated and cultured purely (some organisms cannot be grown in culture)
3. the germ should be able to evoke the disease in another susceptible animal.(may not cause disease all the time)
4. The germ again should be able to be isolated and cultured