Flashcards
BIOL 221 Lab Practical 1
Cards in this deck (80)
- 1In lab we use _____ microscopes, meaning that they have ____ lensesCompound light microscopes, 2
- 2Increasing the magnification of the objective lens decreases the____working distance
- 3The distance from the sample to the lense is theworking distance
- 4Objects viewed under the microscope appear flipped on ____ and _____ planesIt inverts the image across the x and y plane
- 5Resolution in a microscope allows us to____distinguish two objects from each other
- 6How do you calculate resolution distance?divide the wavelength by 2 times the numerical aperture
- 7How can you change the resolution distance?by changing both the wavelength and the diameter of light entering the lens
- 8How big are most bacteria?1-10 micrometers
- 9How do prokaryotes and eukaryotes differ in size?eukaryotes are 10s-100s of micrometers and prokaryotes are 0.2-single digit micrometers
- 10What does a condenser microscope do?it is a unit consisting of one or more lens that focuses the light being emitted from the light source onto the sample
- 11What special substance is used with the 100x objective lens? What's its function? How is it able to perform this function?Immersion oil which prevents the light from refracting between mediums. The glass slide and the immersion oil have the same reflective index so the oil is able to prevent light from refracting from the slide into the air
- 12Which lens can immersion oil be used on?only 100x
- 13What ocular magnification do our microscopes in lab have?10x
- 14What objectives are used in our lab?4x, 10x, 40x, 100x
- 15How do you know if your objective lens is in place?You can see the lighted image and not a black image and it clicks into place
- 16Which objective should be used first?4x
- 17What does the iris diaphragm to and what effect does this have?It adjusts the amount of light going through the condenser and onto the sample. This controls how bright the sample is.
- 18How should you hold a microscope?by one hand under the base and dominant hand on the arm
- 19What does the fine adjustment knob domoves the stage up and down in very small increments. It is used to get a clear and crisp image of the object. It is used after the coarse adjustment knob has been used to find the plane of focus.
- 20What does the coarse adjustment knob do?it moves the stage up and down to bring the sample into the plane of focus
- 21What adjustment should never be used at 100x?coarse adjustment knob
- 22Why must we use stains to observe organisms?the brightfield microscopes light is too bright that is passes right through the sample to be able to view it correctly. It enhances visualization
- 23What should you write in your microscopes observation?SAM-SEC: shape, arrangement, magnification, endospore, motility, color
- 24What bacterial shapes do we observe in lab and what do they look like?coccus - appear as circles, spherical
bacillus - appear as tiny sticks, rod shaped
spirillum - appear as spirals, twisted
filamentous - appear as long threads, usually response to environment - 25What arrangements do we use in lab to classify bacteria?diploid - pairs after division
strepto (chain) - cells divide like diplo but continue to divide alone a plane
tetrad - cells arranged like a packet of 4
staphylo (cluster) - cells arranged like a bunch of grapes - 26What are the SAM_SEC descriptions used for?for observing bacterial cells
- 27What is a chromophore?colored ion that is part of the molecule that absorbs and reflects particular wavelengths of light making them colored part of the stain
- 28How many dyes are used in a simple stain? What charge do they possess?1 dye (CV or safarin) that is positively charged that is attracted to the negatively charged cell wall of the bacteria
- 29What does heat fixing do to the bacteria cell? How is this process beneficial?it melts sugars secreted by the bacteria which fuses the cells to the slide. This is beneficial so when you go to rinse the sample they do not get rinsed off
- 30What type of dye can be sued to stain a bacterial structure, such as flagella? Why can we see flagella with this stain?A simple stain can be used to stain cell structures such as flagella. The stain makes the flagella possible to see because the dye coats the flagella and then it is precipitated along the structure, increasing the diameter
- 31What letters of the SAM-EMC descriptions can be used while looking at a simple stain underneath the microscopeShape, arrangement, magnification, color (only observing color of the stain)
- 32Why doesn't the C of the SAM-EMC descriptors apply to simple stains?Color is to observe if the bacteria is gram positive (purple) or gram Negative (pink) which uses a series of chemicals and dyes
- 33What charge do negative charged stain carry? How do they interact with the cell wall? What is the effect of their interactions with the cell wall?These dyes are negative (acidic) and so is the cell wall of bacteria which makes them repel this dye causing the background to be dyed
- 34Give an example of a negative stain dyes, and its advantage over other stainsindia ink or nigrosine. An Advantage of the negative stains is the bacterial doesn't have to be heat fixed
- 35What structure can be visualized under a microscope with both a simple and a negative dye? How does it appear?Bacterial capsule. And using both stains you can stain the background and the cell leaving a clear halo (the capsule)
- 36What does a negative stain look like beneath a microscope?
- 37What letters of SAM-EMC descriptions can be used while looking at a negative stain beneath the microscope?Shape, arrangement, magnification
- 38Where on the slide do we apply the bacteria and the India ink?on the edge
- 39How does india ink get spread out on the slide?Using another slide edge smear the cells across the first slide
- 40What is a differential stain used for?it uses more than one dye to distinguish between group of bacteria or structures of a single organism
- 41What are some examples of differential stains?Gram stain, acid fast stain, spore stain
- 42How many dyes are used in a gram stain?2
- 43What allows the second stain to work on the bacterial cells in gram stains? How does it work?The decolorizer (OH-) will dissolve the outer membrane of the gram negative bacteria allowing the crystal violent iodine complex to leak out of the cell wall and then the safranin is used to simple stain the cells. The thick peptidoglycan in gram positive cells allows the crystal violet iodine complex to be trapped in the cell wall
- 44What was the significance of color in the gram stains we did in lab?purple = gram positive
pink = gram negative - 45What is the significant difference in gram negative and positive bacteria?Gram negative bacteria have two cell membrane with a thin peptidoglycan cell wall in between and gram positive bacteria have one membrane and a thick peptidoglycan cell wall
- 46What dye is used first in our gram stains from lab? What color does this correspond to?Crystal Violet, purple
- 47What is the purpose of Gram's iodine?To fix the crystal violet into the cell which forms complexes with the crystal violet. The complexes are harder to remove from cell walls to cytoplasm
- 48What counter stain is used in the gram stain?safranin
- 49Where do we apply our dyes and gram iodine for a gram stain?on the sample
- 50How and where do we apply decolorizer? and how much do we apply?With the slide at an angle apply 10-20 drops letting it run over the sample
- 51How many loops of bacteria should be used in gram stain?3
- 52How should your smealr look?cloudy
- 53What problems can resultfrom a thick smear?only the outer cells will loose the purple color and the inner gram negative cells that are clumped together will remain purple
- 54How old should a bacteria be to perform a gram stain?cultures between 20-24 hours old - dont want cells with weak or old peptidoglycan layers
- 55What letters of the SAM-EMC descriptors apply to a gram stain?shape, arrangement, magnification, color
- 56What two options can we use to dry a slide?placing the slide in the incubation room at 37 degrees C for 5 minutes or holding the slide high above the flame
- 57Why do we use Acid-Fst stains?some cell walls have lots of mycolic acids in their exterior making it impermeable to water soluble dyes like crystal violet. It can distinguish a small subset of acid-fast organisms such as mycobacterium
- 58What type of stain is used instead? and with what?a special lipid sobule dye in combination with heat is used. Primary dye is carbol fuschin and secondary dye is methylene blue
- 59What does the heat do to the cells?it acts as the mordant. It traps the carbol fuschin in the mycolic acids
- 60What is used to destain some of the bacteria cells?acid alcohol (HCl + ethanol)
- 61Contrast how acid-fast stains anf non-acid fast stains react to acid-alcoholAcid-fast bacteria will retain the carbol fuschin in the cell wall lipids whereas the non-acid fast bacteria will quickly lose it
- 62What do the bacterial cells in an acid-fast stain look like underneath the microscope?acid fast = pink
non-acid fast = blue - 63What structure does a spore stain make visible?spores
- 64What is the primary stain in a spore stain? and what color does it appear as?malachite green, bright green, it is applied with heat so it can penetrate the vegetative cell and the endospore
- 65What is the secondary stain in a spore stain?safranin, appears as pink
- 66What is the purpose of the heat and how does secondary stain work?The malachite green can only be applied with heat to stain the endospore and the green dye on the vegetative cell has weak bonds so it is easily removed with water and then the safranin is used to stain the vegetative cell and since heat isn't used it doesn't stain the endospore
- 67How do bacteria appear in a spore stain underneath a microscope?the endospore is a bright green and the vegetative cell is pink
- 68What letters of the SAM-SEC descriptors apply with a spore stain?Shape, arrangement, magnification, endospore
- 69What are the different types of endospores observations?central - in the middle of the vegetative cell
subterminal - between the end and the middle
terminal - at the end
full spore - no vegetative cell - 70How do we obtain toothpicks and swabs in lab?from the materials bench
- 71How do we clean slides in lab?70% ethanol
- 72Where do we place our slides?in the slide box drawer
- 73Where do we place used swabs and toothpicks?in biohazard bin
- 74Where do we get stains in lab?at work station by the sink
- 75What was the urpose of the wet mount experiment?to use a wet mount to characterize a mixed community of organisms
- 76What characteristic or microorganisms can be observed using the wet mount sldie that differs from the heat fixed slide?we can observe motility of small eukaryotes that range from 10-100 micrometers because of most bacteria size we are unable to observe motility of bacteria using a light field microscope
- 77Why is pond water used for this experiment?gives us organisms from all three domains of life so we can see interactions in a community of organisms
- 78What are the four main groups of eukaryotes in pond water?archaeplastida (algae and diatoms)
excavata (flagellated protozoa)
amoebozoa (amoebas)
fungi (mold and yeast) - 79Explain archaeplastida nutrients, cell wall, motility, and cellular makeup-oxygenic photosynthetic organisms
-cellulose or silica based cell wall
-motile or nonmotile via flagella/gliding motility
-unicellular or multicellular - 80—
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- Biology Flashcards on BIOL 221 Lab Practical 1 , created by Mekenzie Cecil on 19/02/2022.
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