Exam 2 Flashcards
How do you prepare a smear
- aseptically a thin film of a specimen is spread on a slide
- Film is air dried
- then heat fixed (adhere and kills things on slide)
what is staining?
procedure that use dyes to add color to microbes or cellular structures
what are dyes?
chemicals added to microbes
what are basic dyes?
have positivity charged ions that help them adhere to negatively charged bacteria
Ex. Crystal Violet, Methylene Blue, and Safranin
What are acidic dyes?
have negative charged ions that are attracted to background
bacteria appears colorless against a stained background
Ex. Nigrosin
What is a simple stain?
use 1 dye
determine shape and arrangement
what is differential stain
places bacteria into categories
what are special stains?
stains specific part of microbes
Ex. ENDOSPORE STAIN, Negative Stain, and Flagellar Stain
how do you make a gram stain?
- make smear
- Crystal Violet –> 1 min
- Rinse with water
- Iodine –> 1 min
- Decolorize with ethyl alcohol
- rinse with water
- Safarrin –> 1 min
8 rinse with water - blot dry
Gram positive bacteria appears
Why?
purple
Ex. bacillus
have many peptiodglycan and they retain primary dye
gram negative bacteria appears
why?
red/pink
Ex. E. Coli
have few peptidoglycan that allow decolorization of primary dye and adherance to the counterstain
how do you make an acid fast stain?
- make smear
- carbolfucshin –> microwave –> 1 min
- cool and decolorize with acid alcohol
- rinse with water
- methylene blue – 30 seconds
- rinse with water
- blot dry
Acid Fast positive bacteria appears
why?
bright red
waxy material called mycolic acid
Once heated carbolfuchsin are applied and not decolorized with alcohol and appear read
Acid Fast negative bacteria appears
whY?
blue
if bacteria doesnt contain mycolic acid carbolfuchsin is decolorized with acid alcohol and methylene blue adheres
What are the steps for endospore stain?
- make smear
- Malachite green –> microwave –> 1 min
- cool rinse with water
- Safranin –> 45 seconds
- Rinse with water
- blot dry
* view on oil immersion lens
What are the results of spore stain?
if spore present –> green ( can be inside or out of cell)
bacteria cell –> red
Ex. of positive Bacillus and Clostridum
what are the reasons for the spore stain results?
spore are resistant to mild heat but heating in the microwave allows them to open –> absorb malicite green stain
bacteria cells are decolorized with water and counter stain adheres (red) to cell
what are the steps for a negative stain?
- mix bacteria with Nigrosin on one end of slide
- Use second slide, spread suspension over entire slide
- Air dry
what are the results for Negative Stain?
used to determine capsules (structures that surround cell wall)
if capsule is not present it wont accept the stain and will appear as light spots against a dark background
prokaryotic characteristics
DNA not in a membrane (no nucleous) very small cell wall have peptidoglycan no membrane bound organelles Ex. bacteria
eukaryotic characteristics
DNA in a membrane (nucleous) larger and more complex not all have cell wall bu most membrane bound organelles Ex. Human, plant , and fungi
what are some similarities in prokaryotic and eukaryotic cells?
contain carbohydrates, protein, lipids, and nucleic acids
use chemical reaction to metabolize food build protien and store energy
contain cells
what is the size of prokaryotes?
0.1 um ( 10 ^ -6) to 50 um in diameter
why is the size significant in prokaryotes?
all less space and food so can reproduce and adapt quickly
what is coccus shape?
spherical
what is bacillus shape?
rod
what is spirillum shape?
spiral
what is the plemorphic shape?
many shapes
what is strepto shape?
chain
what is the staphylo shape?
grape- like clusters
what is the diplo shape?
two (pair)
what is tetrad shape?
group of four
what is flagellum?
structure used for motility
what are monotrichous?
one flagellum at one end
what is amiphitrichous?
one flagellum on each end
what is lophotrichous?
turf of flagella at one or more ends
what is peritrichous?
flagella around entire surface
what is the movement of using flagellum?
run
tumble
rotation of flagella is clockwise or counterclockwise
move in one direction
stop and change directions
what is taxis?
positive
negative
movement toward or away from a stimulus
towards
away
what is chemotaxis?
movement involving chemical
what is phototaxis?
movement involving light
what is geotaxis?
movement involving gravity
what is fimbriae?
appendage that is shorter and straighter thatn glagella
2 to 100’s per cell
used for attachement
what is pili?
longer than fimbriae
1 to 2 per cell
used in conjugation
what is glycocalyx?
made of polysaccharides
found outside cell well
cell protection
what are types of glycocalyx?
capsule
sime layer
what is a capsule?
glycocalyx firmly attached to cell wall
protects bacteria from phagocytosis
what is slime layer?
glycocalyx loosely attached to cell wall
protects from water loss
what is the prokarytoic cell wall like?
semiridgid structures outside cell membrane
what is the function of prokaryotic cell wall?
protection and give shape
what are things to know aobut prokaryotic cell walls?
can only be seen clearly with an electron microscope
site where many antibiotics damage bacteria
what is peptidoglycan?
main component of cell wall it contains 2 monosaccharides NAG ( N-acetylglucosamines) NAM ( N-acetylmuramic) amino acid for crossbridge
what is gram positive cell wall consist of?
25 - 30 layers of peptidoglycan
teichoic acid
what is teichoic acid?
acidic polysaccharide
give cell surgace a negative charge
prevents lyse
what is the gram negative cell wall consist of?
10 layers of peptidoglycan
no teichoic acid
contain additional wall layer called LPS outside peptidoglycan
what is LPS?
LipoPolySaccharide
layer is toxic to humans, is responsible for symptoms of infections and is resistant to many antibiotics
what is the cell membrane?
structure below cell wall
forms a phospholipid bilayer similar to eukaryotic cells
what is the function of cell membrane?
acts as selective barrier
site of ATP production
What is simple diffusion ?
movement of molecules from areas of high to low
what is osmosis?
diffusion of water across cell membrane high to low
what is a solute?
substance dissolved in a solvent
Ex. salt
what is a solvent
a liquid
Ex. water
what is solution
mixture of the two or more substance
Ex. Salt water
lower concentration of solutes ouside the wall would be?
hypotonic solution
what does hypotonic solution consist of?
higher concentration of water outside celle
water moves into the cell
Lysis could happen
higher concentration of solutes outside the cell is?
hypertonic
what does a hypertonic solution consist of?
higher concentration of water inside the cell
water moves out
crenation could happen
what is isotonic solution?
equal concentration of both solutes
cells remain intact
what is cytoplasm?
jelly-like substance found inside cell
80% is water
contains carb., proteins, lipids, and genetic material
what is a nucleoid?
cluster of genetic material
what are ribosomes?
structures directs protein synthesis
composed of 2 sub units
smaller than eukaryotic
very numerous in cells that are actively growing
what are inclusions?
large storage molecules made of C N S P formed when these elements are abundant not always present
what are endospore?
structure formed when nutrient are limited
contain thick cell walls
able to survive extreme environments conditions
(heat, lack of water, or exposure to chemicals)
can live for 25 million years
what happens to endospores when conditions are favorable again?
convert back to vegetative state
what is sporulation?
process of making spores
who has spores?
bacillus and clostridium
how are spores killed?
autoclave –> heat under pressure for 20 min
