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Eukaryotes. Cell wall made of chitin. Molds and mushrooms are multicellular consisting of masses of mycelia which are composed of filiaments called hyphae. Yeasts are unicellular
What type of microorganism has a peptidoglycan cell wall, has DNA that is not contained in a nucleus, and has a flagella?
Scientific names are denoted how in writing?
Underlined or Italicized. The Genus is capitalized and the specific epithet is not.
Name characteristics of a bacteria
1. are prokaryotic, 2. have peptidoglycan cell walls, 3. grow by binary fission, 4. have the ability to move
List some beneficial activities of miroorganisms.
1. used as food for humans, 2. use CO2, 3. provide N for plant growth, 4. used in sewage treatment processes
Name an essential function performed by bacteria.
decomposition of organic material and recycling elements
Which type of microscope would be best to use to observe a stained bacterial smear?
Compound light microscope
Which type of microscope would be best to use to observe unstained bacterial cells; the cells are small, and no detail is needed
Which type of microscope would be best to use to observe unstained live tissue when it is desirable to see some intracellular detail?
Which type of microscope would be best to use to observe a sample that emits light when illuminated with ultraviolet light?
Which type of microscope would be best to use to observe intracellular detail of a cell that is 1um long?
Which type of microscope would be best to use to observe unstained live cells in which intracellular structures are shown in color?
differential interference contrast microscope
Calculate the total magnification of the nucleus of a cell being observed through a compound light microscope with a 10x ocular lens and an oil immersion lens.
The maximum magnification of a compound microscope is (A)____; that of an electron microscope is (B)____. The maximum resolution of a compound microscope is (C)____; that of an electron microscope is (D)___. One advantage of a scanning electron microscope over a transmission electron microscope is (E)____.
A. 2000x B.100,000x C. 0.2um D. 0.0025um E. seeing 3D details
Why is a mordant used in the Gram stain?
The mordant combines with the basic dye to form a complex that will not wash out of Gram-positive cells.
Why is a mordant used in the flagella stain?
The mordant accumulates on the flagella so that they can be seen with a light microscope. Flagella are very thin otherwise.
What is the purpose of a counterstain in the acid-fast stain?
It stains the colorless non-acid-fast cells so that they are easily seen though a microscope
What is the purpose of a decolorizer in the Gram stain?
the decolorizer removes the color from Gram-negative cells.
What is the purpose of a decolorizer in the acid-fast stain?
The decolorizer removes the color from non-acid-fast cells.
Fill in the following table regarding the Gram stain: (format: color after the step: Gram Positive, Gram Negative). Crystal Violet (A)___, (B)___. Iodine (C)___, (D)____. Alcohol-acetone (E)___, (F)____. Safranin (G)____, (H)____
(A) purple, (B) purple. C)purple, (D)purple. (E)purple, (F)colorless. (G)purple, (H)red
Assume you stain Bacillus by applying malachite green with heat and then counterstain with safranin. Through the microscope, the green structures are:
Carbolfuchsin can be used as a simple stain and a negative stain. As a simple stain, the pH is?
higher than the negative stain
Looking at the cell of a photosynthetic microorganism, you observe that the chloroplasts are green in brightfield microscopy and red in fluorescence microscopy. You conclude that ___?
chlorophyll is fluorescent
Name 3 functionally analogous pairs of stain.
Crystal violet and carbolfuchsin. Safranin and methylene blue. Ethanol-acetone and acid-alcohol.
Assume that you are viewing a Gram-stained field of red cocci and blue bacilli through the microscope. You can safely conclude that you have what?
Two different species.
In 1996, scientists described a new tapeworm parasite that had killed at least one person. The initial examination of the patient's abdominal mass was most likely made using what?
In the Gram stain, on step could be eliminated and still allow differentiation between GP and GN cells, what is that step?
Using a good compound light microscope with a resolving power of 0.3um, a 10x ocular lens, and a 100x oil immersion lens, would you be able to discern two objects separated by 3um? 0.3um? 300Nanometers?
Why isn't the Gram stain used on acid-fast bacteria? If you did Gram stain acid-fast bacteria, what would their Gram reaction be? What is the Gram reaction of non-acid-fast bacteria?
The waxy covering of the acid-fast bacteria would not decolorize with the acid-alcohol from the Gram Staining method. Thus, all would appear to be GP.
Describe each of the following: a. lophotrichous, b. monotrichous, c. peritrichous, d. amphitrichous, e. polar
a.) more than one flagella at each end. B.) one flagella C. flagella all around. D.) One flagella at each end. E.) the flagella is at a pole (the end of the microbe)
Describe the following: a. spiral, b. bacillus, c. coccus, d. spirochetes, e. streptobacilli, f. staphylococci
a. curved, corkscrew, spiral. B. rod C. spherical. D. corkscrew E. links of rods. F. cluster of spheres.
Compare and contrast simple diffusion and facilitated diffusion
Both allow materials to cross the plasma membrane from a high concentration to a low concentration without expending energy. Facilitated diffusion requires carrier proteins.
compare and contrast active transport and facilitated diffusion.
Both require enzymes to move materials across the plasma membrane. In active transport, energy is expended.
compare and contrast active transport and group translocation.
Both move materials across the plasma membrane with an expenditure of energy. In groups translocation, the substrate is changed after it crosses the membrane.
Explain how the Gram stain works to distinguish the two types of cell walls.
The gram-negative bacterium initially retains the violet stain, but is is released when the outer membrane is dissolved by the decolorizing agent. After the dye-iodine complex enters, it becomes trapped by the peptidoglycan or GP cells.
Why does penicillin have no effect on most Gram-negative cells?
The outer layer of the GN cells prevents penicillin from entering the cells.
How do essential molecules enter cells through GP and GN walls?
essential molecules diffuse through the GP wall. Porins and specific channel proteins in the GN outer membrane allow passage of small water-soluble molecules.
What group of microbes is characterized by cells that form filaments, reproduce by spores, and have peptidoglycan in their cell walls?
Name 4 distinguishing characteristics of prokaryotic cells.
they usually have a single, circular chromosome. They lack membrane enclosed organelles. They have cell walls containing peptidoglycan. Their DNA is not associated with histones.
What happens when a GP bacterium is placed in distilled water and penicillin
the cell will undergo osmotic lysis
What happens when a GN bacterium is placed in distilled water and penicillin
Water will move into the cell
What happens when a GP bacterium is placed in an aqueous solution of lysozyme and 10% sucrose?
no change will result; the solution is isotonic
Normal microbiota prevent growth of ______. The normal microbiota produce growth factors such as folic acid and vitamin K.
microbes that attach to solid surfaces and grow into masses. Ex on rocks, pipes, teeth, and medical implants.
opportunistic pathogens are:
microbes that are usually normal microbiota but become pathagens under certain circumstances.
In Brightfield Illumination:
Dark objects are visible against a bright background. Light reflected off the specimen does not enter the objective lens.
in darkfield illumination:
light objects are visible agains a dark background. Light reflected off the specimen does enter the objective lens.
When would you use a Transmission Electron Microscope (TEM) vs. a Scanning Electron Microscope (SEM)?
TEM is used for examining internal structures. 10k-100k magnification. Resolution is 2.5nm. SEM is used for viewing surface ultrastructures. 1k-10k mag, resolution is 20nm.
Describe simple stains
Use of a single basic dye (ex methylene blue). Mordant can be used to fix the stain or coat the specimen to enlarge it. Can use to study morphology and can see arrangement of cells.
Describe Gram Stain.
Divides into GP and GN. Just used for bacteria. Can see morphology and arrangement. Purple = GP, red = GN
Describe Acid-fast stain
Cells that retain carbol-fuchsin stain in the presence of acid-alcohol are called acid-fast. Non-acid-fast cels lose the stain when rinsed with acid alcohol and are then counterstained (ex methylene blue or brilliant green). Acid-fast = red, Non-Acid-fast = blue. Can diagnose TB or leprosy.
Describe Negative Staining for Capsules.
internal cells are stained but external capsules are not. Background is dark = "negative" stain.
Describe Endospore staining
Primary stain: heat is used to facilitate the uptake of the stain into the thick wall of the endospores. Decolorize the cells with Water. Counterstain cells with safranin.
the cell does not have a nucleus. Ex. Bacteria and archeae. One circular chromosome, not in a membrane. No organelles. Peptidoglycan cell walls. Binary fission.
microbe that has a true nucleus. Paired chromosomes in nuclear membrane. Organelles. May have polysaccharide cell walls (human cells do not). Mitosis.
Glycocalyx is another name for what?
capsule. It is outside the cell wall, sticky, allows cell to attach, and prevents phygocytosis (getting eaten).
Peptidoglycan is a
polymer of disaccharide: N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). These are arranged alternatingly and linked by polypeptides.
Describe the differences between GP and GN cells.
GP: Thick peptidoglycan, Teichoic acids. GN: thin peptidoglycan, no teichoic acids, outer membrane.
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