Lab 3 Flashcards
Pipettes are used to
transfer small amounts of liquids with accuracy and repeatability - Microliter
How to convert mililiters to microliters?
Mili to micro = 3 decimals to the right
Micro to MIli = 3 decimals to the left
Pipettes come with what 3 different sizes? and what are the volumes measured?
P20 - 2-20 ul
P200 - 20-200 ul
P1000 - 100 - 1000 ul
Bacterial shapes
Cocci
Coccobaccili
baccili
Vibrios
Spirilli
Spirochetes
Pleomorphic
Cocci - sphere
Coccobaccili - short rod
baccili - rod
Vibrios - curved
Spirilli - rigid spiral
Spirochetes - flexible spiral
Pleomorphic - Variety of shapes
Bacterial arrangements
1 plane
2 cells?
Chain?
Perpendicular plane
4 cells?
cube?
Irregular plane
2 types
1 plane
2 cells - diplo
Chain - strepto
Perpendicular plane
4 cells - tetrad
cube - sarcina
Irregular plane
2 types - Staphylo & palisades
Negative staining is good to
observe morphology, size and arrangement of bacterial cells
Negative staining differs from gram staining in
does not require a heat fix
uses one chromogen called nigrosine
What are the 2 benefits that not heat fixing will provide?
bacteria will not shrink from heat
hydrophobic microbes can be visualized
Nigrosine carries a negative charge which will
Repel the negative charge of the bacterial membrane (teichoic acid and lipopolysaccharide)
The NIgrosine dye will surround the bacterial cells and not dye them
What is the term for variety of shapes seen in a given sample
pleomorphism
What is the purpose of determining shape and arrangement of bacterial culture?
to be able to determine distinct/specific shapes or orders and characteristics if microbes in order to identify them. i
What is one type of culture medium that may have an effect on shape and arrangement
broth medium
What is the measurement used for most bacteria?
Micrometer
a millionth of a meter
Can a rod-shaped bacteria look like a cocci in some cases?
yes if its standing on head or tail could look speherical
Mega
Kilo
Milli
micro
nano
pico
Mega - one million
Kilo - One thousand
Milli - One thousandths
Micro - One millionth
Nano - one billionths
Pico - One trillionth
l
ml
ul
Why should you never exceed the micropipette limits?
Why do you keep the micropipette vertical?
why do you release the plunger slowly?
it will knock off the calibration
to keep the sample out of the nosecone
so fluid is not sucked up into the nosecone
Why is it important to limit the quantity of cells in negative stain?
to be able to see the bacteria, if too much they can overlap
What are the practical uses of negative stains for studying bacteria
some bacteria cannot withstand heat fixing
