Robert HookeFirst to describe microorganisms<br>
Antoni Van Leeuwenhoek&nbsp;first to see bacteria
LIGHT MICROSCOPYinvolves passing visible light transmitted through or reflected from the sample through a single lens or multiple lenses to allow a magnified view of the sample
How to increase the resolving power of a microscopeuse immersion oils-increase the NA
RESOLUTION LIMIT"The minimum angular separation between two points that can still be perceived as separate by an observer <span style=""color: rgb(0, 170, 0);"">Defined as: d = 0.61 x λ / NA</span>"
Stains are applied in order to...?enhance the visibility of cells and identify certain characteristics<br>
What are&nbsp;Stains?are salts comprised of positive and negative ions – one of these ions is coloured
Basic dyesthe cation is coloured
Acidic dyes –the anion is couloured
3 techniques of staining1. simple<br>2.differential<br>3.special
Simple stain<ul><li>Aqeous or alcohol solution of a single basic dye</li><li>Primary Purpose : highlight the entire microorganims so that we can see the entire shape or size&nbsp;</li></ul>
mordantAdditive which is used to increase the affinity of the stain for the sample by increasing the stain
Aseptic techniquecollection of practices that allow preparation and maintenance of sterile (no living organisms) media and solutions<br>
Pure cultures:cells from only a single type of microorganism
Enrichment culture techniques:isolate microbes having particular metabolic characteristics from nature
Louis Pasteur: chemist and microscopistdiscovered that living organisms discriminate between optical isomers<br>discovered that alcoholic fermentation was a biological (not just chemical) process
Robert Koch (1843–1910): physician and microbiologist" experimentally demonstrated the link between microbes and infectious diseases<span style=""color: rgb(0, 170, 0);""> (germ theory of infectious disease) </span><br> identified <span style=""color: rgb(0, 170, 0);"">causative agents </span>of anthrax, tuberculosis, and cholera"
Sergei Winogradsky (1856–1953)&nbsp;demonstrated that specific bacteria are linked to specific biogeochemical transformations (e.g., Nitrogen and S cycles)
chemolithotrophyoxidation of only inorganic compounds to yield energy, no carbon<br>
Martinus Beijerinck"<span style=""color: rgb(0, 170, 0);""></span> Developed <span style=""color: rgb(0, 170, 0);"">enrichment culture technique </span><br>&nbsp; Selectively encourages growth of specific organisms <br>&nbsp; &nbsp; Isolated first aerobic nitrogen-fixing bacterium: Azotobacter <br>&nbsp; &nbsp; First to observe a virus (tobacco mosaic virus)"
What makes bacteria excellent models for fundamental nature of lifeAbility to grow bacteria rapidly under controlled conditions
Metabolic model chemistry:Certain macromolecules and reactions are universal
horizontal gene transfer Bacteria can transfer DNA amongst each other –
What made it possible to build the first tree of lifeRibosomal RNA (rNA) present in all cells
Phylogenetic tree:epicts phylogeny (evolutionary history) of all cells
metagenomics:: microbial genomes/fragments can be recovered from environmental DNA samples