Lab Exam 2 Flashcards
The organism that forms a mutualistic relationship between fungus and algae or prokaryotic cyanobacteria
Lichens
Fungi include both unicellular (_______) and multicellular organisms (________)
Yeasts
Molds and mushrooms
Fungi are often identified by…
- type and appearance of asexual spore they produce
- what kind of structure is responsible for spore production
- whether the hyphae are septate or non-septate
What is it called when fungi can grow in either a yeast form or a mold form depending on the environment?
Dimorphic
- some pathogenic fungi have this characteristic which makes it important to identify in the clinical setting
The name for bakers yeast
And why is it frequently used in scientific research?
Saccharomyces cerevisiae
- it’s genome has been sequenced
- it’s genetics are easily manipulated
- And it is very easy to maintain in the lab
Asexual spore forming structures generally fall under two types:
- conidia: were spores are produced and freely released
- sporangia: where spores are contained in a sack-like head
What is used to specifically stain chitin?
Lactophenol cotton blue
Infections with fungi are called…
Mycoses
What is the most clinically relevant division in fungi that contains pathogenic species?
Phylum Ascomycota
Contains both yeasts and molds
This is a serious lung infection in those that are immunocompromised, disproportionately affecting those with HIV or AIDS. It is commonly found in pigeon feces
Cryptococcus neoformans (yeast)
Causes histoplasmosis, and can be found in bird or bat feces. It is found as mold in the environment, but takes on yeast form in the lungs once inhaled.
Histoplasmosis capsulatum
Causes a respiratory illness called valley fever. It is also dimorphic
Coccocoides immitis
Causes athletes foot and ringworm (Which as a group are considered Tinea infections)
Dermatophytes like Trichophyton
Protists are divided into two broad categories:
Protozoan (heterotrophic and animal like)
And algae (autotrophic)
Protozoans can have multiple life stages, though the two most common are characterized by a moving, metabolic stage called a ________, and another dormant, protective stage with a wall, called a _____ for when environments are more harsh
Trophozite
Cyst
These have green chloroplast, flagellum and red eyespot (photoreceptor)
Euglena
Parasitic worms, commonly called, ________, I am multicellular, mostly macroscopic members of phylum Platyhelminths and Nematoda. Not all are parasitic.
Helminths
Flatworms have mouthparts like a scolex that helps them to attach to tissues, are segmented, and produce eggs in sections of their bodies called proglottids.
Cestodes
Includes both cestodes (flatworms) and trematodes (flukes). Most are helminths in this phylum are also hermaphroditic.
Phylum platyhelminthes
A dioecious cestode with scolex and proglodids that can cause human disease
Platyhelminthes-Teania
A cestode transmitted to dogs by fleas
Platyhelminthes- Dipylidium caninum (tapeworm)
Includes organisms like roundworms, hookworms, and pinworms. Most have separate sexes and also reproduce by laying eggs.
Phylum Nematoda
is endemic to Chad, Ethiopia, Maui and, in South Sudan. Is one of the longest roundworms, reaching up to 31 inches. Ingested by drinking unfiltered water.
Nematoda-Dracuncilus medinessis (guinea worm)
Why do endospores not readily take up malachite green dye without extra effort?
Surrounded by proteins in their cortex (peptidoglycan, keratin) as well as dipicolinic acid.
Heat is used as a mordant to force the due into the endospores
Malachite green can be easily washed out of _________ cells which have much thinner cell walls.
Vegetative
They will be stained with safranin (pink)
Staining endospores which will appear green, and vegetative cells that will appear pink is an example of what type of staining?
Differential Stain
It differentiates between endospores and vegetative cells
Some _________ bacilli have the ability to produce endospores
Gram-positive
Also Colstridium
The nitrate reduction test assesses….
If the bacterium is capable of reducing nitrate to nitrite or nitrogen gas/oxide
If it is red after adding nitrate A & B then it is positive
If it is yellow, add zinc, if it then turns red it’s negative
If it stays yellow after zinc is added, then it is positive (means it produced nitrogen gas or something beyond nitrite)
How is pasteurization performed?
-milk heats to 161°F for 15 seconds and then rapidly cools to 39°F
Or
-ultra pasteurization- milk is heated to 280°F for just two seconds then rapidly cool to 39°F
Both are equally effective at killing bacteria in milk but ultra pasteurization significantly extends the milk shelflife
What test is use to quickly assess the microbiological quality of both pasteurized and raw milk?
How does it work?
Is it qualitative or quantitative?
Methylene blue dye reductase test
The blue color of the dye that is added to the milk will become colorless when the oxygen present in the milk is used up due to bacteria aerobic cellular respiration. The faster the blue color goes away the more bacteria present.
Qualitative
Methylene blue is a dye that is blue when it is _________, but colorless when it is reduced by bacteria
Oxidized
The dye functions as an oxygen detector.
The process of using an organic molecule to regenerate NAD+ from NADH is called…
Fermentation
Two types of fermentation products important in food and beverage production
Lactic acid fermentation and alcohol fermentation
In yogurt…
pyruvate and NADH is converted to…
Lactic acid and NAD+
Alcohol fermentation two-step process:
- pyruvate is converted to carbon dioxide and acetaldehyde
- acetaldehyde acts as an electron exception and is reduced to ethanol and concomitant conversion of NADH into NAD+
End products of carbon dioxide, ethanol, and NAD+
The fermentation of certain carbohydrates can be assessed using what test?
The Phenol Red carbohydrate test
Red = neutral pH Yellow = PH is less than 6.8 (positive test) Magenta = PH is greater than 7.4
What is the purpose of the Durham vial in the Phenol red carbohydrate test?
To trap any CO2 gas that may have been produced during lactose fermentation that would indicate a positive result
What does a bright pink color in the phenol red Carbohydrate test indicate?
The organism converted small proteins in amino acids into ammonia (peptonziation)
Direct counts of bacteria require the use of _________ to enable the observer to differentiate viable and dead bacteria
Trypan blue
When doing a virtual standard plate count only plates that have between _____ colonies are counted
30-300
AdVantages and disadvantages of the standard plate count
Advantages is that only viable cells will be counted
Disadvantage time consuming and some cells may stick together altering the Percision of the count
How to calculate the direct count technique
Cells # =
(# of cells) x (10^4) x (dilution factor)
Divided by
squares counted
Direct count technique….
Cells in suspension are place on a Neubauer or Petroff-Hauser chamber that has been ruled into squares and can hold a specific amount of volume of liquid
- this technique is much faster
- need a certain amount of cells for this to work
- trypan blue can be used to differentiate living and dead cells
Non-halophilic organisms generally require less than ___% NaCl and will die in the presence of increase salinity
1
- this agar is both a selective and a differential medium
- contains 7.5% sodium chloride
- It’s Alex for organisms that can tolerate higher salinity such as Staphylococci
- it can differentiate organisms that can ferment the sugar mannitol
Mannitol salt agar (MSA)
Factors that influence the anti-microbial action of disinfectants and anti-septic‘s include…
- concentration of the chemical agent
- The temperature at which the agent is being used
- The kinds of micro organisms present
- The number of micro organisms present
- the nature of the material bearing the micro organisms
What are the two common antimicrobial mode of action for disinfectants, anti-septic‘s, and sanitizers?
- they may damage the lipids and or proteins of the semi permeable cytoplasmic membrane resulting in leakage of cellular materials needed to sustain life
- they may denatured microbial enzymes and other proteins
The lowest concentration of the anti-microbial agent that inhibits the growth of the species tested
MIC
Minimum inhibitory concentration
Is the lowest concentration of the anti-microbial agent that kills the species tested
MBC
Minimum bactericidal concentration
Antibiotic produced by bacillus subtilis
It disrupts the bacterial cell wall and does not affect bacteria that are not actively metabolizing or lack a cell wall
Bacitracin
Anabiotic used to differentiate coagulase-negative, gram positive cocci.
Novobiocin
A chemical use to differentiate gram-positive beta-hemolytic streptococci
Optochin
Organisms that are commonly used to produce yogurt
Lactobacillus and streptococcus
In both fermentation and respiration…
NAD + is re-generated from NADH
What measurement technique would be useful to quantify a species of bacteria that is difficult to culture?
Direct microscopic counts
