Micro Lab Exam 1 Flashcards
Difference between a prokaryote and eukaryote
Prokaryotes are bacteria and eukaryote is yeast.
Does a prokaryote or eukaryote contain organelles?
Eukaryotes
Which ones stain evenly in tests? Prokaryotes or Eukaryotes?
Prokaryotes. Eukaryotes stain unevenly.
Describe Staphylococcus aureus results from a gram stain
Gram positive cocci in clusters
Describe Bacillus results from a gram stain
large gram positive rod
Examples of fungi genus that have yeast species
Candida albicans, Saccaromyces and Rhodoturula
How do these fungi genus that have yeast species stain?
Gram positive (purple) and football shaped
How do yeasts reproduce
budding
What is the size of yeast in micrometers ?
5-8
What is the size of cocci in micro meters
1
What does Micrococcus luteus stain
gram positive cocci in tetrads
E.coli and Pseudomonas aeruginoa
gram negative (pink) rods
What does it mean if something is enriched?
Means something is added to the plate to enhance bacterial growth
What does nonselective mean?
It means that the media will support the growth of both gram negative and gram positive organisms
What does selective mean?
Means that the media will limit growth by the addition of dyes and antibiotics; it enhances the growth of one type/group of bacteria
What does differential mean?
The plate contains a carbohydrate or property that will allow how to distinguish between organism types
Describe a sheep blood plate (BAP)
Nonselective (bc it grows both gram +/-), enriched (bc it contains 5% sheep’s blood), differential (based on hemolysis)
Describe a MacConkey agar plate
selective (gram - ), differential (for lactose fermentation), and not enriched
Describe ColumbiaCNA
enriched (contains blood), is selective (grows gram +), and differential (hemolysis)
Describe Nutrient agar
nonselective, not enriched (no blood added), not differential (cannot see how biochemicals used)
Alpha (green) hemolysis
partial hemolysis of RBC
Beta hemolysis
clearing; total hemolysios of RBC
Non hemolytic
No change; no effect on RBC
Describe Chocolate Agar
enriched and nonselective
What is a TSI (triple sugar iron) agar?
a nonselective differential slant that identifies organisms based on carb utilization
What is the purpose of immersion oil?
to minimize light scattering. Since light scattering is decreased, the image is clearer and sharper and has better contrast
As objectives increase, what decreases?
depth of field and field of view
Parfocal
If you are focused under on objective, you will be focused under the next with only minimal adjustment
Magnification
making a small object appear larger
Resolution
makes things look more distinct
Do gram stains require cover slips when viewing them under a microscope?
No but they may be used when trying to keep one for a long time
What is the advantage and disadvantage of a slant?
A slant is a good way to store bacteria but it is difficult to determine if the organism is mixed because of small surface area
What is an advantage of an agar plate?
More surface area; you can find isolated colonies
How can you tell if an organism is aerobic or anaerobic in a broth?
Anaerobic organisms grow towards the bottom of the tube. aerobic ogranisms grow near the top
What is an advantage of a broth?
It allows for rapid and large volume growth
What is the disadvantage of a broth?
all bacteria are mixed together
What is a disadvantage of an agar plate?
some bacteria prefer a liquid environment to move around whereas an agar plate limits that
What is hemolysis?
When RBS break open and release their contents (hemoglobin) into the surrounding fluid
What is a deep used for?
storage
What is an advantage of a deep?
It can demonstrate organism motility
How can you tell if a bacteria is moving in a deep?
They swim out from the stab and the deep appears cloudy
What tests can you use to judge the motility of a bacteria?
A deep or a wet prep
What is a wet prep?
sample of fluid from the body mixed with special liquid and examined under a microscope
What are the four culture medias used in microbiology?
a deep, a broth, a slant, and a plate
Which culture media can be used to gage oxygen requirements?
Broths;the bacteria either swims up or down
Difference between needle and a loop
a loop was used to pick up liquids and needle was used to stab media
Specimen
a sample of something that is taken for scientific testing
Depth of field
how sharp the specimen looks based on thickness
Aseptic technique
Procedures to minimize contmaination
What is a contaminant?
an unwanted substance that mixes with another substance making it impure
What are the 3 purposes of aseptic technique?
Maintain integrity of samples, protect workers from contamination, protects lab equipment and work space
At what temperature must you incubate bacteria for them to grow?
body temperature ( 35 C degrees)
What would happen if you incubated bacteria at room temperature?
There would be less or minimal growth
Escherichia coli (E.coli)
gram - (pink) rods
Pseudomonas aeruginosa
gram - rod, aerobic
Micrococcus luteus
large gram + cocci in tetrads
Why is it important to obtain isolated colonies?
One organism type needs to be shown to get an appropriate ID and sensitivity
How should a spill be contained?
Cover the spill with a paper towel and soak the paper towel in 10% bleach. Let it sit for 5 min
What is streaking used to obtain?
Isolated colonies
How to quantitate growth by streak?
1+ is rare to few; 2+ is few; 3+ is moderate; 4+ is many or heavy growth
What two types of contamination does a lab track?
% of respiratory specimens (spit has epithelial cells), % of contaminated blood cultures (skin bacteria)
What are the steps to a gram stain test?
Crystal violet (primary stain), Grams iodine (mordant), Ethanol (decolorizer), Saffranin (counterstain)
How to fix a slide?
with heat or flooding with methanol
Which step in the gram stain test is sensitive on time?
The decolorizing step; also easy to overdecolorize
What is a gram stain used for?
used to differentiate organisms based on their size and shape
What happens to cells in older cultures?
They die; old cells cannot retain the crystal violet iodine complex
Which genera do not stain easily with gram stain reagents and may appear gram variable because of this?
Actinomyes, Arthrobacter, Corynebacterium, Mycrobacterium and Propionibacterium (acne)
What is the purpose of mordants?
Fixes color into the cell; intensifies the color
How does gram positive show purple?
Retains the iodine-crystal violet complex
How does gram negative show pink?
Decolorizer washes out the crystal violet; saffranin (counterstain) stains it pink
What is an acid fast smear?
A staining procedure which uses an increased concentration of phenol and fuchsin to dissolve the waxy cell wall
What is used in an acid fast smear?
carbol fuchsin, decolorizer and methylene blue
What color does an acid fast organism stain?
Pink; nonacid fast organisms stain blue
Examples of some acid fast organisms
Mycobacterium tuberculosis, mycbacterium leprae and nocardia
Whats the difference with acid fast cells?
They contain mycolic acid and have a waxy cell wall which makes them resistant to drying and disinfectants
What is a commensal?
A microorganism that does not cause disease and it can live in harmony with its host
Mycobacterium smegmatis
A gram + acid fast bacillus
What bacteria is one of the most known killers of the world?
Mycobacterium tuberculosis
Rhodotorula
46 different species of yeast, found in environment and milk and juice, 3 are human pathogens
Saccharomyces
a yeast single celled fungus that is not uniformed in shape
What is the best way to look for yeast?
A gram stain
Staphylococcus Micrococcus
Gram and catalase +
