General Microbiology Lecture 1: Introduction

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Questions and Answers

What percentage of bacteria is known to actually cause disease?

0.01% (correct)

0.001%

0.1%

Which environment is NOT mentioned as a habitat for certain microorganisms?

Volcanic caves (correct)

Frozen sea ice

Hot springs

Soil

What role do microorganisms play concerning food?

Preserving freshness

Enhancing nutritional value

Enriching flavors

Causing spoilage (correct)

In addition to humans, which of the following can microorganisms cause diseases in?

Humans, animals, and plants Signup and view all the answers

Which statement about the majority of microorganisms is accurate?

Most are beneficial and harmless to humans. Signup and view all the answers

What does the prefix 'micro-' indicate in the context of microbiology?

Something that is too small to be seen without magnification. Signup and view all the answers

What is the primary focus of microbiology as described?

The examination of life forms that are small and often invisible to the naked eye. Signup and view all the answers

Which statement best describes microorganisms?

They are often unicellular or small clusters of cells that cannot be seen without the aid of a microscope. Signup and view all the answers

What aspect of life does microbiology primarily study?

Small life forms that play crucial roles in various environments. Signup and view all the answers

Which of the following is NOT a characteristic associated with microorganisms?

Visibility to the naked eye. Signup and view all the answers

What role do microbes play in the ecosystem?

They decompose dead organisms and facilitate nutrient cycles. Signup and view all the answers

Which of the following elements are cycled by microbes in nature?

Oxygen, nitrogen, carbon, and sulfur Signup and view all the answers

In what way are humans dependent on microbes?

They assist in the digestion of certain foods. Signup and view all the answers

How do microbes contribute to the balance of nature?

By breaking down organic matter and releasing minerals back into the soil. Signup and view all the answers

Which process is NOT facilitated by microbes in the ecosystem?

Photosynthesis in terrestrial plants Signup and view all the answers

What is the primary focus of pharmaceutical microbiology?

Study of microorganisms essential for drug production Signup and view all the answers

Which of the following products are primarily studied in pharmaceutical microbiology?

Antibiotics, enzymes, and vaccines Signup and view all the answers

Which microorganism is most likely to be studied for its role in producing antibiotics?

Penicillium chrysogenum Signup and view all the answers

What additional component does pharmaceutical microbiology study aside from antibiotics?

Vaccines derived from microorganisms Signup and view all the answers

In pharmaceutical microbiology, which type of microorganism is often researched for its vitamin-producing capabilities?

Bacteria such as Lactobacillus Signup and view all the answers

What is the estimated ratio of bacterial cells to human cells in the human microbiota?

10:1 Signup and view all the answers

Where are the majority of bacterial cells located within the human body?

In the gut flora Signup and view all the answers

Which statement accurately reflects the distribution of bacterial cells in the human body?

There are more bacterial cells in the gut than in any other location. Signup and view all the answers

What can be inferred about the relationship between human cells and bacterial cells in the microbiota?

Bacterial cells outnumber human cells by a significant factor. Signup and view all the answers

What is a notable characteristic of the human microbiota?

It contains significantly more bacterial cells than human cells. Signup and view all the answers

What defines an opportunistic pathogen?

An organism that normally does not harm its host but can cause disease when immunity is compromised. Signup and view all the answers

What characterizes a strict pathogen?

A microbe that can infect essentially all exposed human hosts and causes similar infections. Signup and view all the answers

Which statement is true regarding the relationship between immunity and opportunistic pathogens?

Opportunistic pathogens can exploit low immune responses to cause disease. Signup and view all the answers

What type of host interaction is primarily associated with strict pathogens?

Creates consistent infection patterns across all exposed hosts. Signup and view all the answers

In what scenario are opportunistic pathogens most likely to cause disease?

When the host's immune system is compromised or weakened. Signup and view all the answers

Study Notes

General Microbiology and Immunology Lecture 1: Introduction

The course covers general microbiology and immunology.
Midterm exam is worth 30%, practical exam is worth 60%, final exam is worth 60%.
Microbiology is the study of microorganisms.
Microorganisms are organisms too small to be seen with the naked eye.
Microorganisms include bacteria, fungi, viruses, algae, and protozoa.
- Microorganisms are found almost everywhere, including hot springs and frozen sea ice.
- Most microbes are harmless to humans.
- Microbes decompose dead organisms and matter, playing a role in the balance of nature (ecosystem).
- Bacteria, for example, are instrumental in the digestion of food.
- Microorganisms played an important role during the development of antibiotics.

Impact on Human Health

Many microbes are beneficial.
Some microbes can cause infectious diseases (hazard effect).
Microbes that reside in the body are called normal microbiota.
- Normal microbiota protect the human body from harmful microbes by inhibiting their growth.
- Normal microbiota synthesize vitamins such as folic acid and vitamin K.

Balance of Nature (Ecosystem Balance)

Microbes play a role in decomposition.
Decomposers break down organic material (e.g., remains of dead organisms).
Decomposers include bacteria and fungi.
Microbes can be used for ecological purposes, like cleaning oil spills (bioremediation).

Environmental

Microbes can be used to create safe drinking water.
Microbes can be used to create biodegradable products.

Industrial

Microbes are used in the production of antibiotics.
Microbes are used in the production of insulin.
Microbes are used in genetic engineering.
Microbes are used to produce a lot of food products (cheese, pickles, green olives, yogurt, soy sauce, vinegar, bread, beer, wine).

Agricultural

Microbes are involved in livestock health to make them healthier.
Research into microbes can create disease-resistant crops.

Branches of Microbiology (By Taxonomy)

Bacteriology: study of bacteria.
Virology: study of viruses.
Mycology: study of fungi.
Protozoology: study of single-celled organisms like amoebae.
Phycology: study of algae.
Immunology: study of the immune system and responses to pathogens.

Branches of Microbiology (By Type of Research)

Medical microbiology: study of diseases caused by microorganisms.
- Pharmaceutical microbiology: microorganisms in the production of drugs (antibiotics, vaccines, vitamins).
- Food microbiology: study and control of microorganisms involved in food production and spoilage.
  - Agricultural microbiology: study of microorganisms that affect crop production, soil fertilization, and plant diseases.
- Aquatic microbiology: study of microorganisms and their activities in aquatic environments (fresh or marine water).
- Microbial biotechnology: using microorganisms for industrial applications and tasks related to human and environmental health.

Nomenclature of Microorganisms

Carl Linnaeus established modern taxonomy in 1735.
Binomial nomenclature is used, comprising genus and species (e.g., Staphylococcus aureus or S. aureus).
Genus is always capitalized.
All eukaryotes and prokaryotes use this naming convention.
- Viruses use a different method.

Nomenclature of Microorganisms: Examples

Escherichia coli (E. coli): Discovered by Theodor Escherich, lives in the colon.
Staphylococcus aureus (S. Aureus): Cells are clustered, spherical, and their colonies have a golden colour.

Classification of Microorganisms

Microorganisms are classified into two main groups:
Acellular: Viruses, they lack cells.
Cellular:
Prokaryotes: Prior to having a nucleus, bacteria and archaea. - These lack a nucleus, membrane-bound organelles, and have simple internal structures.
Eukaryotes: True nucleus, fungi, algae, protists, plants, and animals. - These have a nucleus, complex internal structures, and membrane-bound organelles.

Two Types of Cells

Prokaryotic cells (bacteria): lack membrane-bound organelles.
- Notable examples are Chlamydia and Rickettsia.
Eukaryotic cells (others): contain membrane-bound organelles.
- Includes plants, algae, fungi, protists.

Prokaryotic vs Eukaryotic Cells (Comparison Table)

Feature	Prokaryotic	Eukaryotic
Size	Smaller	Larger
Cell wall	Usually present	Present in some types, absent in others
Cytoplasmic membrane	Contains no sterols (except Mycoplasma)	Contains sterols
Organelles	Absent	Present (mitochondria, Golgi bodies etc.)
Ribosomes	70S (30S+50S)	80S (40S+60S)
Nuclear membrane	Absent	Present
Nucleus/Nucleolus	Absent	Present
Chromosome number	Single	Multiple
Division	Binary fission	Mitosis, budding, sexual reproduction

Bacteria

Bacteria are tiny prokaryotic organisms (one-tenth the size of eukaryotic cells).
They have peptidoglycan cell walls (some exceptions).
Bacteria reproduce through binary fission.
Bacteria metabolize organic/inorganic chemicals or via photosynthesis.
Most bacteria fall into general dimensions of 0.75-4 µm.
Bacteria occur in various shapes: bacilli (rod-shaped), cocci (spherical), spirilla (spiral).
Bacteria are abundant in soil, water, and the human gut.
Many bacterial species cause disease, yet some are very beneficial to humans.

Bacteria: Classifications

Shape (spherical, rod-shaped, spiral forms)
Arrangement
Clusters
Chains
Pairs

Normal Microbiota (Flora)

Microorganisms that are found on the surface or deep layers of skin, saliva, oral mucosa, conjunctiva, and gastrointestinal tract.
Most normal microbiota are not harmful.
Some are even beneficial to humans and help maintain health.

Pathogens

Microorganisms that can cause diseases.
- Includes viruses, bacteria, fungi, and parasites.
Pathogens cause disease by invading and replicating within the host.
Opportunistic pathogens: cause disease under specific conditions.
Strict pathogens: always cause disease when the host is infected.

Opportunistic vs Strict pathogens

Opportunistic pathogens usually do not harm the host in normal conditions.
They pose harm only when the host's body is compromised and their immunity is weakened.
Strict pathogens commonly cause infection and similar diseases in almost every infected patient.

Bacterial Classification

Bacteria are classified according to various characteristics (shape, staining properties, biochemical tests, nutrition, and genetic characteristics.)
Bacteria can be categorized based on their habitat (saprophytic/parasitic).

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Description

This quiz focuses on the foundational concepts of general microbiology and immunology. It covers the study of microorganisms, their roles in the ecosystem, and their impact on human health. Understanding these principles is crucial for grasping the complexities of microbial interactions and their implications.