BIOL 203, Microbiology LCC (Final) Correct 100%
There are two cell types - prokaryotic and eukaryotic. List the 7 classes or basic types of
microorganisms and identify each as prokaryotic, eukaryotic, both prokaryotic and eukaryotic, or neither. - ANSWER 1. Bacteria- prokaryotic
2. Archaea- prokaryotic
3. Algae- eukaryotic
4. Fungi- eukaryotic
5. Protozoa- eukaryotic
6. Helminthes- eukaryotic
7. Viruses- neither
What is a bacterial endospore? Explain how endospore-forming bacteria could cause a scientist to believe in spontaneous generation. - ANSWER A bacterial endospore is an organism that is able to survive in extreme conditions due to their tough structure.
Endospore-forming bacteria could cause scientists to believe in spontaneous generation
because, they can survive in extreme conditions that would normally kill bacteria. In spontaneous generation, it is said that living things appear from vital forces existing in nonliving or decomposing matter, but there could be bacterial endospore living in that situation without the scientists knowing.
Describe how organisms are placed in the Three Domain (Woese-Fox) classification system vs how organisms are placed in the Five Kingdom (Traditional Wittaker) classification system. Which classification system is more useful to a microbiologist and why? - ANSWER Organisms are placed in the Three Domain classification system by using the three main branches, "Bacteria," Archaea," and "Eukarya." They are placed in each domain based on what kind of cell they are (eukaryotic and prokaryotic). Although prokaryotic cells are both Domain Bacteria and Domain Archaea, the members of the Domain Archaea are very different from the ones in Domain Bacteria as they are able to
live in severe environments and are also able to produce metabolic byproducts.
Organisms are placed in the Five Kingdom classification system by using certain levels that the organisms need to pass in order to go on to the next level. The bottom level is the domain and the organism works its way up to the top level, which is species.
It is more useful for a microbiologist to use the Three Domain classification system because it classifies organisms into smaller classifications rather than being broad. The Five Kingdom classification system is more observation based while the Three Domain classification system is more DNA based. Why must an electron microscope be used to see most viruses? Why can't they be seen
using a light microscope? - ANSWER An electron microscope must be used to see most viruses because viruses are too small to be seen by the optical microscope. The electron microscope has a magnification of 5,000X to 1,000,000X and it does not use light.
Viruses can't be seen using a light microscope because light microscopes do not have as much magnification as the electron microscope and you will not be able to see the viruses.
What is the difference between a mixed culture and a pure culture of microbes? - ANSWER The difference between a mixed culture and a pure culture of microbes is that
a mixed culture are multiple species growing in a container while a pure culture is one species growing in a container.
Mannitol Salt Agar and MacConkey Agar are two examples of media that is both selective and differential. In your own words describe what selective and differential mean. - ANSWER Selective- Contains one or more agents that restrain growth of a certain microbe(s) but urge the growth of another.
Differential- Allows several types of microbes to grow and show differences among themselves.
All bacteria make humans ill. - ANSWER False
In the three domain classification system, all prokaryotic cells are grouped into Monera. - ANSWER False
Angelina Hesse suggested adding ______ as a thickener to broth in order to make solid
media. - ANSWER Agar
Koch's postulates were used - ANSWER to definitively link one microorganism to one disease.
In this class of microorganisms, all members are prokaryotes. - ANSWER bacteria
The theory that states life can arise from nonliving things and would explain an infection by stating that first the body would be in a diseased state after which microorganisms would appear is - ANSWER spontaneous generation
How would you correctly abbreviate Helicobacter hepaticus? - ANSWER H. hepaticus
Which of the following class(es) of microorganisms can exist as a multicellular lifeform? (Select all that apply.) - ANSWER Helminthes
Algae
Fungi Which of the following classes of microorganisms are made up of eukaryotic cells? (Select all that apply.) - ANSWER fungi
algae
helminthe protozoa
Which of the following classes of microorganisms contain even one member that can make humans sick? - ANSWER fungi
bacteria viruses protozoa algae helminthes
Bacteria are typically larger in size than viruses. - ANSWER true
Microbes are ubiquitous. - ANSWER true
What characteristics do all living organisms have? Do you agree that viruses are not living? Why or why not? - ANSWER Characteristics that all living organisms have is; they are made of cells, they have a metabolism, they have reproduction abilities, they are able to grow and develop, they are able to move, and they have cell support, protection, and mechanisms. I agree that viruses are not living, this is because they are not cells. One of the characteristics of being a living organism is that they need to be made of cells.
How can fimbriae make a bacterial cell more virulent? How can a capsule make a bacterial cell more virulent? - ANSWER We describe a pathogen (bacteria, viruses, etc.)
as virulent when it is either better able to infect and cause disease or cause more harm to the host due to factors such as presence of fimbriae and capsules.
Fimbriae are short, hair-like structures that are attached to the cell membrane. They extend from the cell and make the cell "sticky." The fimbriae allow the cell to attach to things such as the cells of your body. Imagine two bacterial cells totally identical except for the fact that one contains fimbriae and the other does not. If these two cells tried to infect your throat, the cell without fimbriae would quickly be washed away (out of the body via a cough or sneeze, or into your stomach acid via the action of mucous and cilia.) It would have little chance of causing an infection. The cell with fimbriae would be considered more virulent because the fimbriae would allow it to attach to your cells and resist all of the body's flushing mechanisms. It would be much more likely to cause an infection. A bacterial capsule is a gel-like substance made of sugar and water that surrounds the outside of a bacterial cell. The capsule is not antigenic meaning the host immune system doesn't recognize it as something foreign that should be attacked. It also covers many of the things that are antigenic and would spur the host immune system to attack (things like PTG, LPS, etc.) Imagine two bacterial cells, identical except that one has a capsule and one does not. The one without a capsule would be quickly identified and destroyed by the immune system. The one with a capsule would be more virulent because it could evade detection (and destruction) by the host immune system.
What is a biofilm and where might you find one? - ANSWER A biofilm is a complex community of microorganisms attached to a surface. A biofilm forms in pretty much any place that has microbes and moisture. Two common places to find biofilms are on your teeth, and coating the insides of your intestines. In a healthcare setting they can be problematic because they can form on prosthetic hips, heart valves, catheters, etc.
A biofilm forms when microbes attach to a surface. They start to produce an extracellular "glue" that not only keeps them attached to the surface, but also allows new microbes to attach to them. This continues until there are many, many layers of microbes. Biofilms can often only be removed mechanically (use of force) because chemicals will only kill off the top layers, leaving the lower layers to multiply. For example, in terms of removing dental biofilms or plaque, it is much more effective to brush your teeth (mechanical) than it is to use mouthwash (chemical.)
How does a Gram Stain work? Describe each of the 4 reagents used and how they act on a Gram-positive cell vs. a Gram-negative cell. - ANSWER Gram-positive bacteria have thick walls of peptidoglycan that keep the crystal violet during the decolorization process. Gram-negative bacteria have thin walls of peptidoglycan that cause it to lose the crystal violet easily during the decolorization process and are instead stained with safranin.
The four reagents used and how they act are:
Crystal Violet- Gram-positive and Gram-negative have cell walls stained with this dye.
Gram's iodine- Gram-positive, the dye crystals are trapped in the cell. Gram-negative, there is no effect of iodine.
Alcohol- Gram-positive, the crystals stay in the cell. Gram-negative, the outer wall is weakened and the cell loses the dye.
Safranin- Gram-positive, the red dye has no effect. Gram-negative, the red dye stains the colorless cell.
How does Penicillin work? What type of bacteria would it be most effective against? - ANSWER Penicillin is an antibiotic. It affects cell wall synthesis by preventing formation
