Lecture 2 Flashcards
biofilms
- cells secrete material to hold to a surface
- cells signal to each other (quorum sensing)
- protects against dispersion
dispersion
goo of polysaccharides
microbes form a
layer. bad for artificial things in people (pacemakers, catheders, artificial joints). biofilms degrade enamel.
explain why immersion oil is used
it captures more light.
minimum number of genes it takes to be alive
400
bright field microscopy
- use shorter wavelength of light
- increase contract, decrease resolution
- we want to see colors. for gram stain.
phase contrast microscopy
used to look at live specimen.
good for:
-motility
-endospores
phase contrast microscopy cont about lambda
1/4 lambda advanced, 1/4 lambda retarded,=. they are out of phase by 1/2 wavelength.
epifuorescence microscopy
absorbs high energy light (short wavelength),emit lower energy light (longer wavelength).
UV–> blue
blue—>green
green—>red
excite
gives off light. longer wavelength.
electron microscope
- great resolution
- sample is in a vacuum
diplo-
division in one plane
strepto
chains
tetrads
division in 2 planes
octads
division in 3 planes
clumps
random division planes
wet mounts
bw slide and coverslip. view live organisms.
unstained, so use phase contrast or something else (not brightfield)
smears
dead cells are observed
use brightfield microscopy to see colors. heat fix so bacteria are stuck on slide.
