Microbio Lec 2
Terms
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Lec 2
- The light Microscope
- Use and limits -
- used to look at cells w/ low
resolution
- resolution limit is .2
nanometers
- Bright field is used to
distinguish between density -
Lec 2
- The light Microscope
- components
- Ocular -
- Adds extra 10 x of
magnification
- user looks through ocular -
Lec 2
- The light Microscope
- components
- Objective -
- actually magnifies specimen
- vary on magnification -
Lec 2
- The light Microscope
- components
- Stage - - holds slide
-
Lec 2
- The light Microscope
- components
- Condenser -
- lens to focus light on slide
- does not assist in
mangification -
Lec 2
- The light Microscope
- components
- Focusing Knobs - - adjust focus
-
Lec 2
- The light Microscope
- components
- Light - - light source
-
Lec 2
- The light Microscope
- Resolution vs.
Magnification -
- reso is:
distance btwn 2 points where
2 points are still visable
- mangification is:
how big picture is -
Lec 2
- The light Microscope
- Resolution vs.
Magnification
- what determines clarity - - Resolution determines clarity
-
Lec 2
- The light Microscope
- info about magn and reso -
- Light microscope has max
magnification of 1500x
- magnification is result of
each ind. lens magnification
- w/ oil, 1000x magn and .2
micrometer resolution -
Lec 2
- The light Microscope
- Bright field microscopy -
- light is background
- dark is specimen
- w/out stain, microbes look
transparent
- some have pigments which can
be seen -
Lec 2
- Simple Stains
- Positive -
- stains actual microbe
- remains purple after stain
- shows shape of microbe and
growth (both pos and neg do) -
Lec 2
- Simple Stains
- Negative -
- stains background around
microbe
- shows shape of microbe and
growth (both pos and neg do)
- NO HEAT FIXING,
- use neg stain when
1 - microbe is fragile
2 - size is important (heat
shrinks) -
Lec 2
- Differential Stains -
- stain techniques that stain
different microbes different
colors -
Lec 2
- Differential Stains
- Gram Stain -
1 - Flood heat fix smear w/
crystal violet
2 - add Iodine
3 - decolorize w/ alcohol
4 - counterstain w/ safranin -
Lec 2
- Differential Stains
- Gram Stain
- results -
- if still violet
microbe is Gram pos
- if red
microbe is Gram neg -
Lec 2
- Prokaryotic Cell envelopes -
- Includes all cell membranes
and cell walls -
Lec 2
- Prokaryotic Cell envelopes
- Murein -
- a specific type of
peptidoglycan found only in
cell wall of bacteria -
Lec 2
- Prokaryotic Cell envelopes
- Gram Pos -
- Have thick Cell Wall outside
cell membrane -
Lec 2
- Prokaryotic Cell envelopes
- Gram Neg -
- Have a thinner cell wall
- Have (2) cell membranes
- an outer membrane
- and the internal cell mem. -
Lec 2
- Prokaryotic Cell envelopes
- Bacterial Cell membranes -
- Fatty acids block most
molecules
- Permeable to H20
- Active transport needed for
other molecules -
Lec 2
- Prokaryotic Cell envelopes
- Archea Cell Membrane -
- NO fatty acids
- uses phytanyl for bilayer
- uses biphytanyl for unilayer -
Lec 2
- Prokaryotic Cell envelopes
- Archea Cell Membrane
- Bilayer Cell mem. -
- Uses Phytanyl with C20 chains
- Creates a bilayer cell mem.
- links 4 Isoprenes together
- Unstable at high temp -
Lec 2
- Prokaryotic Cell envelopes
- Archea Cell Membrane
- Unilayer Cell Mem. -
- Uses Biphytanly w/ C40 chains
- creates a unilayer cell mem.
- Stable at high temp -
Lec 2
- Prokaryotic Cell envelopes
- Murein composition in
Bacterial Cell walls -
- Glycan chains of Alt. NAG -
NAM
- NAMs have short peptide chains
that are cross linked
- Peptide chains give rigidity -
Lec 2
- Prokaryotic Cell envelopes
- Murein composition in
Bacterial Cell walls
- Lysozyme action -
- found in tears and such
- lysozyme attacks murein at
NAG-NAM linkage -
Lec 2
- Prokaryotic Cell envelopes
- Murein composition in
Bacterial Cell walls
- Gram Pos Comp -
- Cross links occur between
Lys and D-Ala -
Lec 2
- Prokaryotic Cell envelopes
- Murein composition in
Bacterial Cell walls
- Gram neg Comp -
- Cross links occur between
Dap and D-Ala -
Lec 2
- Prokaryotic Cell envelopes
- Techoic Acid and Gram Pos
cell wall -
- In gram pos cell walls, they
have techoic acids
- embedded in cell wall and
stick out
- repeating glycerol and
ribitol units linked via
phosphodiester bonds
- allow for identification of
microbes -
Lec 2
- Prokaryotic Cell envelopes
- Gram Neg outer cell mem
and(LPS) -
- Has Lypopolysaccharides (LPS)
- 3 major parts
1 -Lipid A - causes fever
and shock
2 -Core - conserved sugar
form same for all gram -
3 -AgO - highly variable and
immunogenic -
Lec 2
- Variations on Cell envelopes -
- all bacteria susceptable to lysozyme at NAG-NAM linkage
- Mycoplasma and thermoplasma
have no cell wall
- Mycobacterium have wax in cell wall -
Lec 2
- Mycobacterium
- Characteristics and
special staining -
- Have Wax (mycolic acid) in
cell wall
- causes turbuculosis and
leprossy
- needs ACID FAST STAIN to be
seen -
Lec 2
- S Layer -
- Outermost part of cell
envelope
- made of crystalline or glyco
protein structure
(honeycomb)
- some archaens have s-layer
instead of cell wall
- also found in gram pos -
Lec 2
- S Layer
- purpose -
- No one knows
- does not add rigidity
- maybe protection from viruses
- useful for nanotechnology