Samenvatting
Microbiology summary
- Vak
- Microbiology
- Instelling
- Rijksuniversiteit Groningen (RuG)
Summary of microbiology
[Meer zien]Voorbeeld 4 van de 65 pagina's
Voorbeeld 4 van de 65 pagina's
In winkelwagengesponsord bericht van onze partner
Verkoper
Volgen
Voorbeeld van de inhoud
Microbiology lecture 1 13-4-2021Chapter 1:
Microbe – microorganism
• A microbe is commonly defined as a living organism that can be seen by a microscope
(traditional) that range from millimeters in size to 0.2 micrometers.
• There are several contradictions to this definition, including super-sized
microbial cells, microbial communities, and viruses
• A genetic definition includes single-celled organisms that derived from a single
ancestor.
• Includes prokaryotes (bacteria and archaea), and certain eukaryotes (algae,
fungi, and protozoa).
KEY microbiology events
• Robert Hooke observes the microscopic world (1665)
• Antonie van Leeuwenhoek observes bacteria with a single lens (1676)
• Agostino Bassi de Lodi noted cases of microbes associated with pathology (1835)
• Ignaz Semmelweis observes chlorine reduces pathogens on doctors’ hands (1847)
• Florence Nightingale shows statistical correlation of sanitation and mortality (1855)
• Louis Pasteur notes that microbes did not appear spontaneously, and can produce
lactic acid or alcohol (1864, 1857)
• Ernst Haeckel defines microbes in a different class than plants and animals (1866)
• John Tyndall observes that bacterial spores survive boiling, but are killed by cyclic
boiling and cooling (1881)
• Alexander Flemming discovers penicillin (first antibiotic) is made by fungus (1929)
• William Costerton describe biofilms as the major form of existence of microbes
(1978)
First sequenced genome
bacteria
Robert Koch’s postulates link between infection and disease
• 1. The microbe is found in all cases of the disease but is absent from the healthy
individual
• 2. The microbe is isolated from the diseased host and grown in pure culture
• 3. When the microbe is introduced into a healthy, susceptible host, the host shows
the same disease
1
, • 4. The same strain of microbe is obtained from the newly diseased host. When
cultured, it shows the same characteristics as before.
Louis Pasteur and immunization
• Louis Pasteur is more famous for his work on Immunizations and the smallpox virus.
• Given the situation with COVID, and vaccinations, the usefulness of vaccines against
viruses are highly relevant (despite not being microbes).
• Most vaccines inject a damaged or dead virus into the host, so that the
immune system can attack the weakened virus and create antibodies.
• A recent development of mRNA vaccines for COVID skip the recognition phase
and help the host produce the protective proteins.
Vaccines vs. antiseptics/antibiotics
• Vaccines work against viruses, in that they utilize the virus infection mechanism to
produce the antibodies against them. – ineffective against live bacteria
• Antiseptics come in two forms: physical and chemical
• Physical antiseptics usually include heat (burner flame, autoclave)
• Chemical antiseptics are molecules that kill not only bacteria, but also the
host if ingested. (f.e. ethanol for cleaning surfaces)
• Antibiotics are chemicals that would kill the microbes but leave the host unharmed.
Due to host variability, this has been adapted for killing > 99.9% of microbes.
Support ecosystems
• Aerobic environments are abundant with oxygen.
• Microaerophilic environments have reduced oxygen levels and may led to multiple
forms of metabolism
• Capnophilic (CO2 loving) environments are a form of microaerophilic
environments.
• Anaerobic environments are lacking in oxygen.
• Strict anaerobic environments are completely void of oxygen (oxygen is lethal).
• Within a growing biofilm, any or all of these environments can exist
simultaneously.
endosymbiosis & Nitrogen
cycle
five kingdom scheme
2
,Three kingdom scheme (tree of life)
• Eukarya (eukaryotes) – multi-celled organisms
• Bacteria (common bacteria) – single celled organisms, of which proteobacteria
(mitochondria) and cyanobacteria (chloroplasts) were derived
• Archaea – (rare bacteria) including thermophiles, sulfur oxidizers, that are not
susceptible to antibiotics
Proposed by Carl Woese
Chapter 2:
The microbial cell gram positive/ gram negative
Bacterial cell shapes and arrangements
The gram stain
3
, Chapter 3:
The microbial cell
• To grow and multiply, a microbial cell must obtain nutrients faster than its
competitors (or share them for mutual advantage, like symbiotes with plants)
• Most bacteria share these 3 traits:
• Thick, complex outer envelope (cell wall or membrane, with or without thick
peptidoglycan layer)
• Compact genome
• Tightly coordinated functions
• In contrast:
• Archaea have unique membrane and envelope structures to allow survival in
extremes
• Eukaryotic cells have extensive membranous (internal) organelles
Components of an average bacterial cell
• Water, 70% by mass
• Proteins, 16% by mass
• RNA, 6% by mass (0.7% mRNA)
• Phospholipids (membrane) 3% by mass
• Lipopolysaccharides (outer membrane) 1% by mass
• DNA, 1% by mass
• In biofilms, the water content of the structure can be closer to 80 – 90% water.
Cell Fractionation
• It is possible to separate components of a cell based on their mass.
• Ultra-centrifugation techniques (high speed) are used to pellet heavier components,
while leaving the lighter components in suspension.
• After removing the heavier pellet, the centrifuge speed is increased and a lighter
component is next pelleted. (repeated for all interesting components)
• Protein separation in gels (SDS-PAGE) works in a similar manner (diffusion, rather
than centrifugation).
Membrane components
• Membrane lipids (phospholipids) form a bilayer that separates water environments
of the internal cell and surrounding exterior environment
• Membrane proteins
• Provide structural support
• Detect environmental signals
• Secrete virulence factors and communication signals
• Function with ion transport and energy storage
• Thick peptidoglycan structure is a target for several antibiotics (against gram positive
bacteria)
Methods of transport across the membrane
• Passive diffusion – small, uncharged molecules
4
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper annerixtvanderwal. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €5,49. Je zit daarna nergens aan vast.
Is Stuvia te vertrouwen?
4,6 sterren op Google & Trustpilot (+1000 reviews)
Afgelopen 30 dagen zijn er 67474 samenvattingen verkocht
Opgericht in 2010, al 14 jaar dé plek om samenvattingen te kopen