Microbiology Exam #1 Study Guide

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CH. 1 1. Define the following terms: microorganism (microbe), pathogen, and infectious disease. -Microorganism: Bacteria, archaea, algae, protozoa, helminths, fungi, and viruses. -Pathogen: A disease causing microorganism. -Infectious Disease: Diseases caused by a pathogen. 2. Explain how an infectious disease is different from a non-infectious disease. -An infectious disease is caused by a pathogen where as a non-infectious disease is caused by another factor. 3. Explain the Germ Theory of Disease and how it differs from older concepts of disease. -The Germ Theory of Disease states that infectious diseases are caused by microorganisms (microbes). Previous ones include the Miasma Theory of Disease (smelly odors cause disease) and spontaneous generation (life created from nonliving things). 4. Identify the specific contributions of scientists/ microbiologists discussed in class. -Hooke: 1 st individual to view cells under microscope -Leeuwenhoek: 1 st person to view bacteria, “animalcules”. -Jenner: 1 st smallpox vaccine. -Semmelweis: Advocated handwashing. -Pasteur: Disproved spontaneous generation, supported Germ Theory of Disease. -Lister: Introduced aseptic technique. -Cohn: Discovered endospores. -Koch: Verified Germ Theory of Disease, Koch’s postulates. -Fleming: Discovered Penicillin, antibiotics available in nature. 5. Identify the five different pathogens. -Bacteria, Protozoa, Fungi, Helminths, and Viruses. 6. Identify where the five different pathogens belong on the tree of life. -Bacteria = prokaryote, Protozoa = eukaryotes, fungi = eukaryotes, helminths = eukaryotes, viruses= none, acellular 7. Compare and contrast prokaryotes and eukaryotes. -Prokaryotes: No nucleus, no organelles, single/circular chromosomes, 70S ribosomes, reproduce through binary fission. Their DNA is floating in the cytoplasm. -Eukaryotes: Have nucleus and organelles, multiple chromosomes, 80S ribosomes, reproduce through mitosis/meiosis. Their DNA is housed in the nucleus. 8. Define human microbiome and normal microbiota. -Human microbiome is a broader term for all of the microbes present in our body (normal microbiota). This includes bacteria, archaea, fungi, protozoa, and viruses that do not cause harm and are sometimes beneficial. 9. Differentiate between the terms pathogen and normal microbiota. -Pathogens are disease causing microbes whereas normal microbiota is not harmful, they are normal in our bodies and can be beneficial sometimes.

10. Conclude whether a pathogen is prokaryotic or eukaryotic based on its physical characteristics. -Bacteria= Prokaryote -Protozoa= Eukaryote -Fungi=Eukaryote -Helminth= Eukaryote -Virus= Neither (acellular) 11. Describe taxonomic hierarchy. -Taxonomic hierarchy is a form used to classify living things starting from general to specific. 12. Differentiate between the terms “genus” and “species.” -Species is a type of genus, meaning it is a specific type of a broad form of genus. Genus is the first part of the binomial nomenclature and species is the second part. 13. Type out the genus and species name of a microbe in the correct format. -E. coli 14. Distinguish a virus from other pathogens. -Viruses are acellular and have a simple structure. They are mainly made up of two main structures, a protein shell and genetic material. They are neither alive or dead. CH. 3 Pt. 1 1. Recognize and name the shapes and arrangements of bacteria. -Cocci, bacillus, and spirillus. 1) Bacillus & Coccus 2) Diplobacilli & Diplococci 3+) Streptobacilli & Streptococci 4) Tetrad (cocci) Grape (cocci)= Staphylococci Spirilla (least to most spiral) = Vibrio, Spirillum, Spirochete 2. List the structures that all bacteria share in common. -Cell membrane, cytoplasm, ribosomes, cytoskeleton, 1 or a few chromosomes. 3. Describe and draw the structure of the cell membrane. -Phospholipid bilayer, phospholipids contain a hydrophilic head & hydrophobic tails. 4. Describe the function of the cell membrane. -Cell membrane regulates the passage of things in & out of the cell. Also, a site for chemical processes like ATP production. 5. Describe peptidoglycan. -Peptidoglycan is a repeating framework of long glycan chains cross-linked by short peptide (protein) fragments. 6. Describe, draw, and label the structure of a Gram positive and a Gram negative cell wall. -Gram (+): Thich cell wall made of peptidoglycan over the cell membrane. Teichoic & Lipoteichoic Acid. Acids add structural stability to wall. More resistant to physical stress.

-Gram (-): Outer membrane over thin peptidoglycan cell wall over cell membrane. Lipopolysaccharides & Porin Proteins. More resistant to chemical stress. 7. Compare and contrast, in detail, the Gram positive and Gram negative cell walls. -Gram positive cell wall contains a thick layer of peptidoglycan while the gram-negative cell wall has a thin layer of peptidoglycan. Gram positive is more resistant to physical stress, gram negative is more resistant to chemical stress. 8. Explain how the bacterial cell membrane and the bacterial cell wall are distinct in structure and function. -The cell membrane functions in the regulation of materials passing through. Cell walls function in structural stability for the cell and determine shape. 9. Explain how the antibiotic penicillin affects the bacterial cell wall. -Penicillin disrupts the peptidoglycan in the cell wall by preventing the synthesis of peptide bridges that crosslink the glycan chains of peptidoglycan. This leads to the bacteria exploding from osmotic pressure. 10. Explain how the cell walls of Mycoplasma and Mycobacterium differ from Gram positive/ Gram negative cell walls. -Mycoplasma bacteria lack a cell wall, instead they have a membrane with sterols. Mycobacterium contain mycolic acid in their cell walls (acid-fast staining). 11. Describe the structure and function of a flagellum, axial filaments, fimbriae, pili, S layer, capsule and slime layer. -Flagellum: Tail-like structure made of flagellin that is used for motility. Can be on the outside or inside (spirochetes). -Axial filaments: Internal flagella found only in spirochetes, wriggly movements. -Fimbriae: Numerous bristle fibers made of pilin that help bacteria attach. -Pili: Made of pilin, function in attachment and DNA transfer (can also transfer antibiotic resistance) to another bacteria. -S layer: Only made under hostile environment, “armor.” -Capsule: Type of glycocalyx, used for attachment and protection from phagocytosis. -Slime layer: Type of glycocalyx, protects against loss of water and nutrients. 12. Explain how an axial filament is different from a flagellum. -Axial filament is an internal flagellum that are unique to spirochetes, flagella are on the outside and result in locomotion (360-degree spins). 13. Identify different flagellar arrangements. -Monotrichous: Single -Lophotrichous: Tuft on one end of the cell (like hair) -Amphitrichous: One or more on both ends of cell (like antennas) -Peritrichous: Distributed all over cell surface 14. Compare and contrast fimbriae and pili in respect to structure and function. -Fimbriae and pili are both made of pilin. Fimbriae is mainly used for the attachment of the bacteria onto another surface, while a pilus is mainly used for the transfer of genetic

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information (DNA, which could also include antibiotic resistance). Fimbriae are short and numerous, pilus is long and few. CH. 3 Pt. 2 1. Describe the nucleoid and the plasmid. -The nucleoid is a dense area within the cell where the DNA aggregates, not encased but DNA chill in that area. NOT A NUCLEUS -Plasmids are extrachromosomal pieces of DNA that are not essential to bacterial growth/metabolism. Sort of “superpower” can be taken away and the bacteria still survives. Plasmids can be transferred from one bacteria into another using a pilus. 2. Compare and contrast the function of the nucleoid and the plasmid. -Nucleoid is where the DNA stays. The plasmid can carry genes for antibiotic resistance or genes for producing toxins/enzymes. 3. Describe the structure and function prokaryotic ribosomes. -Structure: Ribosomal RNA and proteins. -Function: Protein synthesis * 70S 4. Describe the structure and function of inclusions. 5. Describe an endospore. -Dormant stage of a bacteria created when conditions are unfavorable. Helps protect them and keep them alive, once conditions better they come back. Endospores are harder to kill. 6. Compare and contrast an endospore and a vegetative cell. 7. Explain the clinical significance of endospores. 8. Explain the role of endospores in the transmission of C. diff in a clinical setting. 9. Explain the role of healthcare workers in the spread of C. diff in a clinical setting. 10.Describe in detail a C. diff infection along with its risk factors, how it is spread, prevented and treated. SPECIAL TOPIC STRAINS 1. Define and describe a strain using examples. -A strain is a different clone of the same bacterial species that are NOT identical in every way, they are a genetic variant. An example is Salmonella enterica vs Salmonella enterica Heidelberg. GENUS -> SPECIES -> STRAIN 2. Describe how strains can differ externally and/or internally. -Externally, strains can differ in the absence/presence of a capsule, variations in flagellum protein, variations in LPS (Gram -), and variations in other surface molecules. Internally, they are different in the absence/presence of plasmids (antibiotic resistance) and in the production of toxins. They are still the same species but have different structures and/or ways of working. 3. Explain how strains can be identified.

-Strains can only be identified using genotyping methods. Since they are still the same species, if you grow them they look the same as the original and you would be unable to tell if it is a strain or not. The only way to identify them is through looking at their genome. 4. Explain the significance of strains from a healthcare perspective. -Strains are significant because they can differ in pathogenicity (less, more, or not pathogenic) and they may also require different treatments than the original. This could be challenging from a healthcare perspective because if a strain were to arise, the treatment that worked for one may not work for another. CH. 4 1. Name the three eukaryotic pathogens. -Protozoa, fungi, and helminths. 2. Identify structures found in eukaryotic cells and not found in prokaryotic cells. - 3. Compare and contrast eukaryotic vs. prokaryotic flagella in structure and function. -Prokaryotic Flagella: Hollow tube, made of flagellin. Creates propeller-like motion. -Eukaryotic Flagella: Made of microtubules in a 9 and 2 arrangement. Creates wavelike motion (whips back and forth). Not hollow. 4. Describe the structure and function of eukaryotic ribosomes and cilia. -Ribosomes: Structure= Ribosomal RNA & proteins 80S Function= Protein synthesis -Cilia: Structure= Made of microtubules, short & numerous Unique to eukaryotes (Protozoa) Function= Motility 5. Differentiate between yeasts and molds in regard to structure and reproduction. -Yeasts: Unicellular, use budding (asexual reproduction in yeast). -Molds: Multicellular, use spores for reproduction. 6. Define the terms dimorphic fungi and mycosis. -Dimorphic Fungi: Can exist as both a yeast and a mold depending on the growth conditions. Are yeasts at body temp and molds at room temp. -Mycosis: A disease caused by a fungus. Primary pathogens can sicken even healthy people. Opportunistic pathogens sicken people with weakened immune systems. * Fungi tend to be opportunistic pathogens. * 7. Compare and contrast endospores vs. fungal spores vs. cysts in regard to function. -Endospores: Function for survival under harsh conditions (production processes differ). These are the MOST resistant. -Fungal Spores: Created by fungi for reproduction. These are the LEAST resistant.

-Cysts: Created by Protozoa for survival under harsh conditions. They are less resistant than endospores. 8. Describe the general lifecycle of a helminth. EGG -> LARVA -> ADULT WORM 9. Differentiate between an intermediate and definite host. -Intermediate host = Where the egg develops into the larvae. -Definite host = Larvae develop into adult worm. 10.Describe the life cycle of Enterobius vermicularis. -Pinworm, originates from us and the eggs emerge from the anus. Scratching contaminates the hand where it could then either contaminate the same person if swallowed (self-infection) or contaminate another person when the eggs are transferred to a new host (cross-infection). In this case humans are both the intermediate & definitive hosts. 11.Conclude whether a pathogen is a protozoan, fungi, or helminth based on unique characteristics of each pathogen. - CH. 5 1.Distinguish a virus from other pathogens -A virus is acellular and is a lot simpler in its when compared to other pathogens. 2. Draw, describe, and label the basic structure of a virus. -A virus has genetic information (DNA or RNA) surrounded by a capsid which is a protein coat. A virus can also be enveloped or non-enveloped, an envelope is a phospholipid membrane that surrounds the nucleocapsid (capsid + nucleic acids/genetic information). An envelope can be a sort of weakness for a virus because it is easy to remove and can make the virus easier to treat. Another structure that a virus can have is spikes which are used to dock onto host cells. All infectious viruses have spikes. 3. Differentiate the different shapes of viruses: icosahedral vs. helical; naked vs. enveloped. -All of the virus shapes are created by their capsids. Icosahedral is a circular shape and it can be either naked or enveloped. The same goes for helical which is a cylindrical tube-like shape. Naked means that the virus lacks an envelope around it. 4. Distinguish a complex shaped virus from other viruses. -Another virus shape is complex, which has an icosahedral shaped “head,” a helical “body” and it also has spikes on the bottom of it. 5. Explain what an emerging infectious disease is and how they relate to viruses. -An emerging infectious disease is a disease that is new or changing and is increasing in number of cases. 75% of emerging infectious diseases are caused by viruses, zoonotic (come from animals), and are vector-borne (spread by the bite of an arthropod). 6. Give examples of emerging infectious diseases caused by viruses.

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-COVID-19, Chikungunya, Zika Virus. 7. Define and explain the following terms: virion, host range, tissue tropism, zoonotic, and vector-borne. -Virion: A fully formed virus. -Host range: The range of hosts that a virus can infect. -Tissue Tropism: The types of tissues that a virus can infect. -Zoonotic: Diseases that normally affect animals but can be spread to humans. -Vector-borne: Diseases that are transmitted by the bite of an arthropod (mosquitos, ticks or fleas). 8. Describe prions and explain how they differ from all other pathogens discussed. -Prions are infectious proteins that cause neurological disease. They differ from viruses and all other pathogens because they do not have genetic material, they are just made of proteins. They cannot be treated, but there have been very few cases of them in humans. 9. Describe viroids and explain how they differ from all other pathogens discussed. -Viroids are plant pathogens made of naked RNA that causes disease in plants/crops. The most important thing about viroids is that they do not infect humans. They do though, infect economically important crops and this could lead to economic loss.

Microbiology Exam #1 Study Guide

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