BI323 Lab Final Exam Flashcards
magnify specimens using a 2-lens system
brightfield microscope
light from the specimen passing into a lens. 4X, 10X, 40X, and 100X
objective lens
What lens do you only use oil immersion for?
100X
rotation of objective lens so that they “line-up” adding a magnification of 10X
ocular lens
How do you determine the total magnification?
multiply the objective lens by the ocular lens
used to focus the specimen. the larger knob on the sides of the microscope
coarse focus knob
What does parfocal mean?
if you face your specimen using 1 objective lens, it should be focused when you rotate to the next objective
slight adjustment to focus the specimen when rotating between objective lens. use the small focusing knob
“fine-tuning” focusing
focuses the light in a small area above the stage
substage condenser
controls the amount of light entering the substage condenser
iris diaphragm
What are the 3 basic shaped of bacteria?
bacillus (rod-shaped), coccus (sphere-shaped), and spirillum (rigid helical shaped)
Why do you stain bacteria?
visualize their overall shape and cellular organelles against a contrasted background
How do you disinfect your work area?
disinfectant solution such as 70% ethanol, 4% bleach solution, or lysol
How do you infect your equipment?
alcohol/ethanol and gas burner
What is the autoclave?
large, self-contained pressure cooker that goes through heating, sterilizing, and cooling cycles automatically
How long and at what temperature should MEDIA be sterilized?
15 minutes at 121C and a pressure of 15 psi
How long and at what temperature should glassware and contaminated articles be sterilized?
30 minutes at 121C and a pressure of 15 psi
How do you disinfect an inoculating loop?
hold the loop in the flame until it glows red
How do you maintain aseptic conditions when collecting bacteria?
flame the loop, remove the cap from the tube, pass it through the flame a few times, collect sample, pass the tube through the flame again, flame the loop
produces individual colonies for observing morphology or separating mixed suspensions of bacteria
isolation streaking technique
How do you perform the isolation streaking technique?
streak only the top 1/4 of the plate while raising the cover of the petri dish at just enough of an angle. turn the dish 90 degrees. make 1 streak from area 1 into area 2 then streak area 2 in a zigzag pattern until 1/4 of the plate is covered. repeat for the remaining 2 areas. MAINTAIN ASEPTIC CONDITIONS THROUGHOUT EACH STREAKING
What temperatures do most fungi grow at?
25C
What temperatures do most NONPATHOGENIC bacteria grow at?
room temperature - 30C
What temperatures do most PATHOGENIC bacteria grow at?
37C
How long do you store cultures?
short - term it can be in an incubator at 30C. long - term it is not practical as some do not survive refrigeration and/or may undergo genetic mutations.
What is simple staining?
provides contrast with the background or to make cellular organelles visible. consists of an aqueous or alcoholic solution of a single dye
What are the most common simple staining dyes?
methylene blue, basic fuchsin, and crystal violet
How do you prepare a heat-fixed smear?
1.) place a drop of water onto a clean slide
2.) flame inoculating loop and mouth of culture tube
3.) remove a small quantity of bacteria
4.) flame the mouth of the tube and replace cap
5.) mix bacteria in water on slide and spread thinly
6.) allow smear to air dry
7.) pass the slide through the flame 3 times and allow the slide to cool
8.) flood the slide with dye for 60 sec.
9.) rinse the slide and blot dry
Why do you heat-fix a smear?
fixing the slide kills the bacteria and causes them to stick to the slide
What is gram-staining?
separates almost all bacteria into 2 groups for bacteriological idenfitication
What color is Gm+ bacteria?
purple/blue
What color is Gm- bacteria?
pink
What are the general steps for gram staining?
1.) prepare smear
2.) flood with crystal violet for 60 sec.
3.) flood with gram’s iodine for 60 sec.
4.) decolorize with 5-6 drops of 95% ethanol
5.) flood with safranin for 60 sec.
Why do bacteria take up Gm stain differently?
differ in cell wall composition. Gm+ bacteria have a thick cell wall layer the alcohol does not readily penetrate to decolorize. Gm- bacteria have thinner cell walls that allow alcohol to readily penetrate
What is differential staining?
more complex than simple ones and use more than 1 stains to differentiate cellular components
based on the resistance of cells stained with hot carbol fuchsin to decolorization by acids
acid-fast staining
What do the results of acid-fast staining mean?
non-acid fast cells are counterstained with methylene blue. acid-fast cells stain red
Why was acid-fast staining developed?
to identify the leprosy microbe and tuberculosis microbe
negative staining that contrasts the capsule between the red cells and a blue background. cannot be heat fixed as the capsule will be destroyed
capsule staining
What is endospore staining?
identify endospores that are difficult to stain. resist decolorization and counterstaining
What do the results of endospore staining mean?
endospores are penetrated with malachite green and everything else is counterstained pink
Who developed acid-fast staining?
Paul Erlich in 1882 while working with tuberculosis
molecular complex made from 2 sugar monomers laid together to form a chain that are then cross-linked to form threads that form mats
peptidoglycan
What is the cell wall of Mycobacterium comprised of?
glycolipids and peptidoglycan
no fresh media is added during bacterial doubling as a result of nutrients available for growth steadily decline and toxic metabolic waste products begin to increase
batch culture
What is the lag phase of a growth curve?
bacteria are introduced into fresh nutrient medium. characterized by no new cell growth as bacteria is adjusting to its new environment
What is the log phase of a growth curve?
culture is growing at its maximum rate and can grow in a logarithmic manner at regular intervals
What is the stationary phase of a growth curve?
rate of new bacteria production equals the bacterial death
What is the death phase of a growth curve?
decline in the total number of viable bacteria
sampling the batch culture at regular time intervals, diluting each sample, and then spread plating a small amount on a nutrient agar plate
viable cell plate count method
What is the goal of viable cell plate method?
to dilute the sample sufficiently to produce a number of individual colonies that are reasonable to count
What is CFU/ml?
reflects the number of viable bacteria per ml that is in a sample obtained for that time period
step-wise dilution of a substance in a solution
serial dilution
What is the equation for CFU/ml?
CFU/ml = # of colonies/(dilution X volume plated)
measures both living and dead bacterial cells/total biomass of the culture based its increase in turbidity
spectrophotometer method
chemical agents that affect the growth of bacteria by either microcidal or microstatic activity
disinfectant
What does microcidal mean?
microorganism killing
What does microstatic mean?
growth inhibiting
What factors affect a disinfectant’s effectiveness?
temperature, pH, concentration, and exposure
What 2 ways do disinfectants create an unfavorable conditions?
1.) interfering will enzyme activity and passage of material in and out of cell membrane and wall
2.) interfering with cell structures
prevent growth of microorganisms helping to preserve the supply of available water and nutrients by affecting some aspect of an organism’s metabolism and altering the cell wall to prevent reproduction
antibiotics
soil organism, rod-shaped, nonpathogenic, Gm+, and forms spores
B. subtilis
normal inhabitant of human intestinal tract, rod-shaped, Gm-, and does not form spores
E. coli
effectiveness of antibiotics/disinfectants with a clear zone around the impregnated disc
zone of inhibition
it provides useful information in differentiating one bacterial species from another
biochemical testing
Why do we study biochemical characteristics of bacteria?
1.) to demonstrate metabolic diversity
2.) biochemical characteristics represent phenotypic characteristics
can cause disease when they get into areas of the body other than where they are normally found
opportunistic pathogens
occurs in the feces of man and other animals, isolated in clinical specimens as an opportunistic pathogen
C. freundii
occurs in water, sewage, soil, dairy products, and feces of man and animals, opportunistic pathogen
E. aerogenes
occurs in the lower part of the intestine of warm-blooded animals, opportunistic pathogen
E. coli
occurs in soil, water, and plant surfaces, opportunistic human pathogen
S. liquefaciens
What is Kliger’s iron agar for H2S?
used for the detection of carbohydrate fermentation
What is Simmon’s citrate agar slant?
used for testing an organism’s ability to use citrate as its carbon source and ammonia as its nitrate source
Interpret results from Kliger’s iron agar
the phenol red turning yellow is an indicator that it is acidic. a black precipitant indicates the production of H2S
Interpret results from Simmon’s citrate agar slant
the change from green to blue means that it can ferment the citrate in the media
process by which some bacterial cells produce energy to fuel other metabolic pathway. required sugar molecules to be broken down into smaller organic end products
fermentation
What 3 types of sugars were used in the sugar fermentation experiment?
sucrose, dextrose, and lactose
Interpret the results from a sugar fermentation experiment
phenol red is a pH indicator that will turn yellow if the acidity increases. gaseous end products are formed in the medium and trapped in the Durham tube. some bacteria may ferment the sugar but produce nonacidic, gaseous end products
insertion of a gene into an organism in order to change the organism’s trait
genetic transformation
What does GFP stand for and what is it?
green fluorescent protein. real-life source of bioluminescent protein
small circular pieces of DNA containing genes for 1+ trait beneficial to bacterial survival
plasmids
What does pGLO plasmid encode?
the gene for GFP and a gene for resistance to amplicillin
How can the GFP gene be switched on and off?
addition of arabinose to the nutrient medium
Interpret the results from the pGLO experiment
transformed cells will appear white on plates not containing arabinose and fluorescent green under UV light when arabinose is included
What is a general description of Wolbachia bacteria?
Gm- parasitic bacteria, infects ~70% of the insect population, 16 supergroups based on ftsZ cluster patterns, causes reproductive and developmental changes
What is feminization?
genetic male organism turn into females by inhibiting androgen production
What is parthenogenesis?
asexual reproduction of female offspring
What is male-killing?
causation of male embryos to die by targeting male chromatin remodeling
What is cytoplasmic incompatibility?
incompatibility between sperm and egg through the silencing of paternal chromosomes
Who discovered the Wolbachia bacteria in 1924?
Marshall Hertig and Simeon Burt Wolbach. classified in 1936
What is Project Wolbachia?
release of non-biting male mosquitoes infected with Wolbachia to breed with non-infected females. released into local areas with high cases of mosquito-borne diseases
Give examples of mosquito-borne diseases
yellow fever, dengue fever, zika virus, chikungunya
What are the main characteristics of N. meningitidis?
aerobic, Gm-, diplococcus, 12 known stereotypes, found in the nasopharynx
What are some symptoms of meningitis?
fever, headache, nausea and vomiting, severe myalgias, upper respiratory infection
What is cerebrospinal meningitis?
infection of the blood leading to the blood brain barrier that has uncontrolled multiplication
What is septicemia meningitis?
infection of mucous membranes that enters and multiples in the bloodstream. leads to infection in the tissues throughout the body causing purpura fulminans
How does meningitidis spread?
spread from host via saliva and other bodily fluids. died upon contact with other surfaces
What 2 mechanisms cause lethality of meningitidis?
1.) infection of epithelia cells by adhesion and multiplication
2.) infection of bloodstream through nasopharynx
What are some symptoms of mononucleosis?
fever, fatigue, loss of appetite, sore throat, swollen lymph nodes, body aches
How does mononucleosis spread?
direct contact with bodily fluids, sharing utensils, drinking from the same glass, sharing chapstick
What is a general description of Epstein-Barr Virus?
HHV-4, first human tumor virus, DNA virus, Gm-, 2 subtypes, toroid shaped protein, double-stranded DNA, outer envelope
How does EBV spread?
oral and sexual transmission
How does EBV/mononucleosis cause cancer?
attacks B-lymphocytes
What is a general description of C. botulinum?
Gm+, rod-shaped, obligate anaerobe, produces spores, motile
What are the 4 types of botulism?
food-borne, wound, inhalation, and infant
What are some symptoms of botulism
fatigue, vertigo, vision problems, difficulty in swallowing, vomiting
What is the mechanism of action of botulism?
absorbed in the colon, passed into the bloodstream, to the nervous system, muscles involved in the respiratory system are attacked causing asphyxiation
What are the way to diagnosis and treat botulism?
diagnosed through stool, serum, and gastric samples. treatment is an antitoxin to prevent further damage
What is a general description of the rabies virus?
RNA virus, Gm-, presence of outer envelope, transmission through the bite of an infected animal that affects the PNS
What are some symptoms of the rabies virus?
flu-like, prickling/itchiness at bite location, dizziness, nausea, muscle spasm, hallucinations
What is a general description of Dengue fever?
spherical shape, presence of viral envelope, RNA virus, 4 different variants
What is the transmission of Dengue fever?
vector borne viral disease that is transmitted through Aedes aegypti mosquitoes
What are some symptoms of Dengue fever?
high fever, severe headache, retro-orbital pain, joint and muscle, fatigue and weakness, skin rashes. there is a vaccine that is only available to past dengue infected patients
What is the diagnosis and treatment of dengue fever?
diagnosed with nucleic acid amplification tests and cross reactive flaviviruses. there is no available treatment
Who discovered C. diff in 1935?
Hall and O’Toole. John Bartlett discovered it as a pathogen caused by antibitoics
What is a general description of C. diff?
enteropathogen, release toxins causing inflammation and damage, leads to severe diarrhea, RNA virus, Gm+
What are some symptoms of C. diff?
diarrhea, fever, nausea and vomiting, stomach pain, fatigue
What is the diagnosis and treatment of C. diff?
diagnosed with white blood cell count, electrolyte levels, albumin levels, and serum lactate levels. treatment is fluids and anti nausea medications and antibiotics
How does C. diff spread?
fecally to orally with the ingestion and germination of spores before reaching the colon
What is a general description of Anthrax?
caused by B. anthracis, spore forming, Gm+, rod-shaped, presence of cell envelope, DNA virus
How does Anthrax spread?
originally found in soil but spreads from animals to humans or from use in biological warfare. contracted primarily from inhalation, skin abrasions, and ingestion
What are the 3 types of lethality of anthrax?
1.) cutaneous
2.) ingestion
3.) inhalation
What are some treatment options for anthrax?
antibiotics and 3 dose vaccine
