C453 V5 Clinical Microbiology Study
Questions and answers (from module 1-19)
2024 Western Governors University
Unit 1: Types of Microorganisms Module 1: Bacteria
Lesson 1: Foundational Contributions
Lesson 2: Characteristics of Microorganisms:
1)Describe the general characteristics of bacteria by answering the following questions.
a.Are bacteria prokaryotic or eukaryotic? Why? Prokaryotic because their genetic material (DNA) is not housed within a true nucleus.
b.Single-celled or multicellular? Why? Usually unicellular
c.Can they be seen with the naked eye? Why? No; typically they are about 1um (need to be at least 100um to be visible without a microscope
2)Describe the following bacterial shapes:
a.Coccus: round/spherical
b.Coccobacillus: short rod c.Vibrio curved rod (comma shaped)
d.Bacillus rod
e.Spirillum: spiral
f.Spirochete: long, loose, helical spiral
3)Describe the difference between a halophilic and a halotolerant microorganism. Halophilic requires high salt concentrations for growth; halotolerant grow in the presence of high salt, but do not require it.
4)Describe the endospores by answering the following questions.
a.What is the function of an endospore? Protects the bacterial genome in a dormant state when environmental conditions are unfavorable
b.How are endospores made? Describe the process in detail. (ex.: What is the first step, what’s next, etc.)
1) DNA replicates 2) membranes form around the DNA 3)Forespore forms additional membranes4) Protective cortex forms around the spore
5) Protein coat forms around the coretex6) spore is released
c.How do endospores germinate? Water and nutrients penetrate the spore coat. The spore coat is broken down, and the cell begins rehydrating. d.Name the bacteria that produce endospores. What diseases do they cause? (Unit 6 will help with the diseases.) gram-positive; Bacillus (B. anthracis) clostridium (c. tetani, c. difficile, c. perfringens, c. botulinum
5)Describe the structure and function of the cell (plasma) membrane. Bilayer composed of mostly phospholipids and proteins; cell-to-cell communication, and sensing environmental conditions and pathogenic virulence factors.
6)Name examples of wall-deficient bacteria. How do they survive without a cell wall? Mycoplasma sp.; they have sterols in their plasma membranes that provide additional support.
7)Describe the function of the cell wall. To protect the cell from harsh conditions in the outside environment.
8)Describe the components of the following cell walls, including the size of the peptidoglycan layer and fully describe any unique components of the cell wall:
a.Gram positive many layers of peptidoglycan with embedded teichoic acid external to the
plasma membrane.
b.Gram negative contain inner membrane, thin layer of peptidoglycan, and an outer membrane containing lipopolysaccharide.
c.Acid-fast 60% lipid (mycolic acid) & 40% peptidoglycan
9)Gram negative cell walls contain an endotoxin called lipopolysaccharide (LPS). What are
the effects of LPS? When is LPS released? Contributes to symptoms such as fever,
hemorrhaging and septic shock. LPS is released when the cell dies.
10)Describe the function of capsules. How are capsules used to promote infection? Capsules allow cells to adhere to surfaces, aiding in the formation of biofilms (colonies of microbes that form in layers on surfaces). The capsule can make it more difficult for phagocytic cells to engulf and kill the microorganism.
11)Describe the function of pili. How are pili used to promote infection? Pili are protein appendages that aid in attachment to surfaces such as host cells which is important for colonization.
12)Describe the function of flagella. Used by cells to move in aqueous environments
13)Describe positive and negative chemotaxis. Positive chemotaxis, movement toward a chemical attractant; negative chemotaxis, movement away from a repellent.
Lesson 3: Microbial Growth and Mechanism
1)What are virulence factors? Product of a pathogen that assists in its ability to cause infection & disease
2)What are exoenzymes? Provide some examples. Extracellular enzymes that enable them to invade host cells and deeper tissues. Glycohydrolase, aminohydrolase, nucleases, phospholipases 3)What are exotoxins? Provide some examples. Protein molecules that are produced by a wide variety of living pathogenic bacteria. Exp: botulinum toxin.
Intracellular-targeting toxins: cholera, tetanus, diphtheria, botulinum
Membrane-disrupting: streptolysin, pneumolysin, alpha-toxin, beta-toxin, phospholipase Superantigens: toxic shock syndrome, streptococcal, mitogenic, streptococcal pyrogenic Module 2: Gram Staining
Lesson 1: Purpose of Gram Staining
Please note that the material in Lesson 1: Purpose of Gram Staining is for task
1 only. Module 3: Viruses
Lesson 1: Acellular Pathogens
1)Describe the basic characteristics of a virus. They do not contain cells; they consist of nucleic acid (either RNA or DNA) surrounded by protein coat (capsid) composed of capsomeres
2)How are naked and enveloped viruses different? How do enveloped viruses gain their envelope? Naked virus is formed with only a nucleic acid and capsid; An enveloped virus is formed with nucleic-acid packed capsid surrounded by a lipid bilayer obtained as viron buds from a host cell.
3)Complete the tables below. Please refer to Table 3.2 “Common Pathogenic Viruses in the “Classification and Taxonomy of Viruses”.
Double-stranded DNA viruses (dsDNA) with envelope
Double-stranded DNA viruses (dsDNA)
Family NameVirus NameInfection or Disease
AdenoviridaeHuman adenovirusResp. infection (common cold)
papovaviridaepapillomavirus Genital warts, cervical/vulvar/vaginal cancer
hepadnavirida
eHepatitis B virusHepatitis BFamily Name Virus Name Infection or Disease
Poxviridae orthopoxvirus Small pox, cowpox
poxviridae parapoxvirus Skin lesions
herpesviridae simplexvirus Cold sores, genital herpes, STDs
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