Microbiology Course Quiz

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Questions and Answers

Which statement correctly describes the binomial system of nomenclature?

Both names are written in uppercase.

The first name is the species and is capitalized.

The first name is the genus and is capitalized. (correct)

The second name is capitalized and italicized.

What is the correct classification for a spherical-shaped bacterium?

Coccus (correct)

Bacillus

Vibrio

Spirillum

Which of the following is a characteristic of spirochetes?

Spherical shape

Short, curved rod

Cylindrical shape

Long spiral-shaped cell (correct)

What is the main method by which most prokaryotes reproduce?

Binary fission Signup and view all the answers

Which term describes bacteria that can have multiple shapes?

Pleomorphic Signup and view all the answers

What is the total number of points available for the undergraduate grading scheme in the course?

250 points Signup and view all the answers

When is the final exam scheduled for the course?

May 5, 2025, from 9:15-11:15 AM Signup and view all the answers

Which of the following components is included in the overall grading scheme for graduate students?

50 points essay assignment Signup and view all the answers

What types of questions might be included in the term tests?

Essay, case study, and true-false questions Signup and view all the answers

Which of these percentages corresponds to a letter grade of 'C' in the grading scheme?

69.6% - 79.5% Signup and view all the answers

How many term tests will undergraduate students take in this course?

3 term tests Signup and view all the answers

What are the main sections into which the course material is divided?

Basic concepts, Host responses, Systematic study of diseases Signup and view all the answers

What has contributed to the dramatic decrease in the death rate from infectious diseases over the last 100 years?

Modern sanitation, vaccinations, and antibiotics Signup and view all the answers

What characterizes emerging infectious diseases (EIDs)?

They are infectious diseases that have become more common recently Signup and view all the answers

Which of the following is NOT listed as an emerging infectious disease?

Tuberculosis Signup and view all the answers

What was the impact of African swine fever in China?

It resulted in the death or culling of over a million pigs Signup and view all the answers

Which of the following factors contributes to the emergence of infectious diseases?

Pathogens’ ability to infect new hosts Signup and view all the answers

What proportion of deaths occur due to infectious diseases in the USA annually?

Many thousand deaths costing tens of billions in healthcare Signup and view all the answers

Which disease has shown a recent increase in commonality that was once considered long-established?

Malaria Signup and view all the answers

How many people worldwide have died due to SARS-CoV-2 from 2019 to 2023?

Over 6 million people Signup and view all the answers

Which of the following diseases is caused by a retrovirus?

Acquired Immunodeficiency Syndrome (AIDS) Signup and view all the answers

What is a characteristic that distinguishes bacteria from archaea?

Archaea do not have peptidoglycan in their cell walls. Signup and view all the answers

Which infectious agent is specifically linked to chronic diseases like peptic ulcers?

Helicobacter pylori Signup and view all the answers

What is a primary reason for the increased susceptibility to infections in immunocompromised individuals?

Weakened immune systems Signup and view all the answers

Which of the following best describes the domain Eucarya?

Contains organisms with a true membrane-bound nucleus. Signup and view all the answers

What factor has been implicated in the spread of infectious agents such as COVID-19?

Greater global travel and mobile populations Signup and view all the answers

Which condition is associated with greater opportunities for infectious agents to spread?

Changing lifestyles Signup and view all the answers

What is a primary factor contributing to antibiotic resistance in pathogens like tuberculosis?

Widespread antibiotic overuse Signup and view all the answers

Which of the following domains includes organisms that lack a true nucleus?

Both Bacteria and Archaea Signup and view all the answers

What aspect of bacteria contributes to their pathogenicity?

Rigid cell walls containing peptidoglycan Signup and view all the answers

What unique structural feature do eukaryotic cells possess compared to prokaryotic cells?

Presence of organelles such as mitochondria Signup and view all the answers

What role do microbes play in the production of probiotics?

They provide health benefits as live organisms. Signup and view all the answers

Which of the following is NOT a commercial application of microbes?

Development of nuclear energy Signup and view all the answers

Which statement about pathogenic microbes is accurate?

Only a small minority cause disease. Signup and view all the answers

In what field do microbes serve as valuable research tools?

Medical Microbiology Signup and view all the answers

What was a significant outcome of the global smallpox vaccination program?

Smallpox was officially eradicated worldwide. Signup and view all the answers

Which of the following is an example of bioremediation?

Sewage treatment Signup and view all the answers

What common misconception exists about the percentage of harmful microbes?

Most microbes are harmful. Signup and view all the answers

Which product is synthesized through microbial processes?

Hydroxybutyric acid Signup and view all the answers

What significant historical event is linked to the influenza pandemic of 1918-1919?

More deaths occurred than in multiple major wars combined. Signup and view all the answers

Study Notes

Medical Microbiology MICR433/533 Spring 2025

Classroom: SDS 100
Class Time: 10:00 AM - 10:50 AM
Instructor: Radhey Kaushik
Office Hours: Tuesdays, 1:00 PM - 2:00 PM
Office: McFadden Biostress Building-SNP 252B
Phone: 605-688-5501
Email: [email protected]
Course URL: https://d2l.sdbor.edu/
Textbook: Nester's Microbiology: A Human Perspective by Anderson, Salm, and Beins, 10th edition, 2022

Grading Scheme (Undergraduates)

3 Term Tests (40 points each): 120 points
1 Final Exam: 80 points
Quizzes, take-home assignments, and in-class activities: 50 points
Total Points Possible: 250 points (converted to a 100% scale)

Grading Scheme (Graduates)

3 Term Tests (40 points each): 120 points
1 Final Exam: 80 points
50 points additional essay assignment: 50 points
Total Points Possible: 300 points (converted to a 100% scale)

Tests and Exams

Format: Written tests can be a combination of essay, case study, short answer, multiple choice, fill-in-the-blank, matching, true/false, etc.
Timing: All quizzes, term tests, and the final exam are conducted in class, during designated class time/final exam time.

Basis for Letter Grade

A: 89.6% - 100%
B: 79.6% - 89.5%
C: 69.6% - 79.5%
D: 55% - 69.5%
F: Below 55%

Term Tests Dates

Monday, February 3rd, 2025
Friday, February 28th, 2025
Wednesday, April 2nd, 2025
Each test is worth 40 points

Final Exam Details

Monday, May 5th, 2025, 9:15 AM - 11:15 AM
Covers material since the 3rd exam (~55-65 points)
Includes comprehensive questions on previously covered material (~15-25 points)

Course Format

3 Sections:
- Review of basic microbiology concepts
- Review of host responses to infection
- System-by-system study of infectious diseases

Microbiology and Microorganisms

Definition: Microbiology is the study of the microbial world.
Existence: Microorganisms have existed for billions of years.
Evolution: Higher life forms evolved from microscopic forms; therefore, microbes are fundamental to all life.
Importance: All organisms, including humans, require the activities of microorganisms to survive.

Microbiology and Microorganisms (Microbes)

Living (cellular): Microorganisms
Non-living (acellular): Other infectious agents
Combined: Collectively called 'microbes'
Properties: Can change their properties, are capable of rapid adaptation/evolution due to rapid generation times and simple genomes, are very diverse, and are both beneficial and harmful.

The Human Microbiome

Location: Skin and mucosa are populated by characteristic communities of microorganisms.
Microbiota/Flora: Collectively called 'normal microbiota' or 'normal flora'.
Ratio (cells): Many sources claim a 10:1 ratio of microbial to human cells, but recent estimates are closer to 3:1 or 1:1.

The Human Microbiome Project

Started in: 2007
Technologies: Used DNA sequencing to characterize microbial communities in the human body.
Definition: The term 'microbiome' has two meanings: • The total genetic content of a microbial community • The microbial community itself
Culture Limitations: Less than 1% of microorganisms can be cultured in a lab; therefore, DNA technologies are frequently used for characterization.

Human Microbiome Roles

Disease Prevention: Normal microbiota prevent disease by competing with pathogens.
Food Degradation: Assist in the breakdown of foods.
Immune System Development: Promote the development of the immune system.
Reduced Allergies: Early exposure to certain microbes may lessen the likelihood of allergies, asthma, and other diseases.
Brain and Behavior, Weight: Affect brain chemistry, behavior, and weight gain.
Imbalance/Health Harm: Disturbances in normal microbial populations can harm a person's health by creating imbalances.
Active Research: The effect of the human microbiome on health and disease is an active area of research.

Microorganisms in the Environment

Recycling: Microorganisms are masters of recycling materials that other organisms cannot break down.
External/Internal Roles:
- External: • Degrading cellulose in plants (leaves/trees) • Sewage and waste-water treatment
- Internal: • Cellulose degradation in the digestive tracts of animals (e.g., cattle, sheep, deer)
Nitrogen Fixation: Microorganisms recycle and use atmospheric nitrogen, converting it into forms other organisms can use

Commercial Benefits of Microbes

Food Production: Used in bread, beer, fermented drinks, yogurt, buttermilk, cheese, and probiotics (live organisms with health benefits).
Bioremediation: Microbes can degrade toxic materials (sewage, waste, water, petroleum, PCBs, DDT, trichloroethylene), oil spills, and radioisotopes to clean up environmental pollutants.
Commercial Products: Microbes synthesize commercial products like cellulose, amino acids, hydroxybutyric acid, hydrogen gas, ethanol, oils, insect toxins, and antibiotics.
Biotechnology: Microbes are critical in biotechnology, such as medically important products (insulin), recombinant proteins, vaccines, and genetic engineering of plants.

Microbes as Research Tools

Model Organisms: Microorganisms are effective model organisms to study metabolism and genetics since they share similar fundamental properties with higher life forms.
Similarities: Similar mechanisms are used by cells in all living organisms, making bacteria easy to study and helping to understand basic scientific concepts.
Growth Rate: Fast growth rate allows for the rapid generation of research data.
Cost Effectiveness: Cultivation in simple and inexpensive mediums allows for more cost-effective study.
Advances: Bacteria and yeast are critical for many major advances in understanding life.

Microbes and Disease

Beneficial Microbes: Most microorganisms are beneficial (~87%).
Disease Causation: A very small minority (~3%) of microbes are pathogens, causing diseases.
Opportunistic Microbes: 10% of microbes are opportunistic.
Medical Microbiology: Medical microbiology focuses on the study of disease-causing microbes (pathogens).
Historical Examples:
- Smallpox: Killed millions
- Plague (1347-51): Killed 25 million
- Flu Pandemic (1918-19): Killed more Americans than World Wars I, II, Korean, Vietnam, and Iraq wars combined.
Modern Advancements: Modern sanitation, vaccination, quarantine, and effective antibiotics have dramatically reduced the rate of infectious diseases.
Continuing Challenges: Infectious diseases remain a significant problem globally, especially with new emerging and reemerging infectious diseases

Remaining Major Challenges (Emerging Infectious Diseases)

Emerging Infectious Disease (EID): An infectious disease whose incidence has increased or is newly recognized.
Examples of EIDs: COVID-19, Ebola, Congenital Zika syndrome, Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS), Hepatitis C, Certain types of influenza (Swine flu), Lyme disease, Acquired Immunodeficiency Syndrome (AIDS), Hantavirus pulmonary syndrome, Mad-cow disease.
Long-established diseases: Long-established diseases (malaria, tuberculosis) are becoming more common recently.

Reasons for Emerging or Re-emerging Infectious Diseases

Pathogen Evolution: Changes in pathogen ability to infect new hosts or increased virulence
Changes in Host Characteristics: Change in virulence of infectious agents
Life Style Changes: Changing life styles that provide opportunities for infectious agents to spread
Antibiotic Resistance: Resistance to antibiotics is increasing.
Vaccination Gaps: Ignorance of childhood vaccinations
Elderly Exposure: Increase of elderly people becoming susceptible to a variety of infections
Global Travel/Mobile Population: Increased global travel and mobile population allowing for more rapid spread of infectious disease
Immunocompromised Hosts: Immunocompromised individuals are more susceptible to serious infections.

Chronic Diseases Caused by Bacteria/Viruses

Peptic Ulcers: Helicobacter pylori
Cervical Cancer: Human papillomavirus (HPV)

Microbial World

Domains: Bacteria, Archaea, Eucarya (Eukarya)
Prokaryotes: Bacteria and Archaea are collectively referred to as prokaryotes (lacking a true nucleus)
Distinction: Though they exhibit some similarities structurally, Bacteria and Archaea have significant differences in their chemical composition and are unrelated.

The Bacteria

Cell Type: Single-celled prokaryotes
Nucleus: Lacks a true nucleus and internal lipid-bound organelles.
Genetic Material: Genetic information stored in DNA in a region called the nucleoid.
Shapes: Commonly spherical, cylindrical, or spiral.
Cell Walls: Have rigid cell walls containing peptidoglycan, which is not found in other domains.
Reproduction: Multiply by binary fission.
Appendages: May have appendages (flagella) for motion, which can also indicate pathogenicity.

The Archaea

Similarities to Bacteria: Single-celled prokaryotes, similar shapes, have flagella and cell walls, multiply by binary fission.
Peptidoglycan Absence: Lack of peptidoglycan in the cell wall.
Extremophiles: Tend to live in extreme environments like high salt, high temperatures, and extreme cold.

The Eucarya

Descriptions: Members of the 'Eucarya' domain are called eukaryotes, which have a true or membrane-bound nucleus and other organelles inside the cell.
Characteristics: • May be single-celled or multicellular • Always have a true nucleus • Contain internal organelles (e.g., mitochondria, chloroplasts) that are more complex compared to prokaryotes. • Have an internal scaffolding called the cytoskeleton to define cell shape.
Example Eukaryotes: Algae, fungi, protozoa, and multicellular parasites (e.g., helminths).

Scientific Names of Microbes

Binomial system: Used to name microorganisms.
Genus: The first name is capitalized and italicized.
Species: The second name is not capitalized, and both are italicized.
Example: Escherichia coli
Abbreviation: First word is abbreviated with the first letter capitalized (e.g., E. coli)
Strains: Members of a species can vary slightly and are given different strain designations (e.g., E. coli strain B or E. coli strain K12).
Informal Grouping: Groups of similar microbes might be informally grouped by names resembling their genus name, but are not italicized (e.g., species of Staphylococcus are called staphylococci).

Morphology of Bacteria

Shape Classification: Bacteria exhibit different shapes, and this characteristic is used to describe, classify and identify them.
Basic Shapes:
- Coccus (spherical)
- Rod (bacillus; cylindrical)
- Further variations: vibrio (curved rod), spirillum (curved rod forming spirals), spirochete (long spiral-shaped cell with a flexible cell wall and unique motility mechanism) and pleomorphic (bacteria vary in shape).
Coccobacillus: A rod-shaped bacteria which is short enough to be mistaken for a coccus

Grouping of Bacteria

Colony Structure: Colony structure is related to the way bacteria divide.
Binary Fission: Prokaryotes primarily reproduce via binary fission
Division Plane: They form chains, packets, or clusters depending on the plane in which they divide.
Identification: Cell groupings (chains, clusters) help in bacterial identification.

Acellular Infectious Agents

Overview: Viruses, viroids, and prions are acellular infectious agents—meaning they lack cellular structure.
Lack of Reproduction: Viruses, viroids, and prions cannot reproduce independently. Therefore, they are not considered living microorganisms and require a host to reproduce.
Viral Structure: A protein coat that surrounds the nucleic material (DNA or RNA), giving them variety of shapes.
Viral Lifestyle: Unable to proliferate outside of a host cell, and depend on the host cell's machinery to reproduce.
Viral Classification: Viruses are considered obligate intracellular parasites/agents.

Viroids and Prions

Viroids: Simpler than viruses, consisting of a single piece of RNA (often lacking a protein coat). They are smaller than viruses and can only replicate inside cells. They are a cause of several plant diseases.
Prions: Composed entirely of protein without any nucleic acid. They are linked with neurodegenerative diseases called Transmissible Spongiform Encephalopathies (TSEs).

Acellular Infectious Agents - Table

Viruses: Consist of either DNA or RNA surrounded by a protein coat. Obligate intracellular agents that utilize host cellular machinery/resources for replication.
Viroids: Consists solely of RNA; lack a protein coat. They are obligate intracellular agents that use host cell machinery for replication.
Prions: Protein-based agents; lack DNA or RNA. Misfolded versions of normal cellular proteins cause normal proteins to misfold.

Next Lecture

Cells and observational methods. (Chapter 3, selected topics).

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Description

Test your knowledge of microbiology with this quiz that covers various topics, including classification, reproduction, and grading schemes. Perfect for students studying the principles of prokaryotic organisms and their characteristics. Challenge yourself and see how well you understand the fundamental concepts in microbiology.