Chapter 1 Flashcards
Virus
Acellular entities that must invade a host to replicate
Viroids
Are infectious agents composed only of RNA. They cause numerous plant diseases
Satellites
They co-infect cells with a virus. They are also called helper virus
Prions
Infections agents composed only of protein and are responsible for causing neurological diseases such as mad cows disease
Walter Gilbert
Coined the term RNA world
Robert Koch (“coke”)
First direct demonstration that bacteria cause disease.
He used mice and Guinea pigs to show that mycobacterium terbculosis caused tuberculosis (TB) which was the lead leading cause of death at the time.
The relationship between a bacteria and its disease is now called a Koch postulate
Louis pasture
Disproved “spontaneous generation”
Created pasteurization
Created vaccine for rabies
Developed theory for “germ theory”
Bright field microscope
Ones you see in highschool labs. They shine light from the bottom
Resolution
Ability to distinguish 2 points
Contrast
White sheep on white hill
Or
White sheep on dark hill
Dark field (light-microscopy)
Light shines from top down
Phase-contrast microscope (light-micro)
2 beams shine and cancel each other out
There’s lots of contrast between points
Differential interference contrast (DIC) (light-micro)
Similar to phase-contrast but it appears more 3D
Fluorescent Microscope (light-micro)
Can use dyes or tags to see things glow
Confocal microscope (light-micro)
Creates very sharp 3D images using a scanning laser beam
Basic dyes
Positivity charged groups that bind to negatively charged molecules
Ex: Safranin
Acidic dyes
Have negatively charged groups that bind to positive charged cell structures
Ex: eosin
Steps to stain bacteria
Step 1: stain with crystal violet (primary stain). Rinse after 1 min
—> all cells will stain purple
Step 2: iodine wash (mordant) Rinse after 1 min
—> all cells will remain purple
Step 3: alcohol (decolorizer). Rinse after 30sec
—> gram positive remain purple
—> gram negative are colourless
Step 4: Safranin (counterstain). Rinse after 30sec
—> gram positive remain purple
—> gram negative become pink/red
Transmission Electron microscope
Shoots beams of electrons through the specimen
Scanning Electron microscope
Shoots and electrons at specimen and reads the reflected electrons (only good for SA)
Scanning probe microscope
Most sensitive form. Uses a small probe to scan along the surface of a specimen. The probe moves up or down in response to the contours. Can measure at the single atom level (doesn’t require dehydration or a high vacuum like electron micro does)
