Chapter 1
Introduction to Microbes and Their Building Blocks
Microorganisms are defined as “living organisms too small to be seen with the
naked eye.” Members of this huge group of organisms are prokaryotes (bacteria
and archaea), algae, protozoa, fungi, parasitic worms (helminthes), and viruses.
Microorganisms live nearly everywhere and influence many biological and
physical activities on earth. There are many kinds of relationships between
microorganisms and humans; most are beneficial, but some are harmful.
Microbes are crucial to the cycling of nutrients and energy necessary for all life
on earth.
Humans have learned how to manipulate microbes to do important work for them
in industry, medicine, and in caring for the environment. In the past 120 years,
microbiologists have identified the causative agents for many infectious diseases.
They have discovered distinct connections between microorganisms and
diseases whose causes were previously unknown. The microscope made it
possible to view microorganisms and thus to identify their widespread presence,
particularly as agents of disease. Medical microbiologists developed the germ
theory of disease and introduced the critically important concept of aseptic
technique to control the spread of disease agents. Our current understanding of
microbiology is the cumulative work of thousands of microbiologists, many of
whom literally gave their lives to advance knowledge in this field.
Excluding the viruses, there are two types of microorganisms: prokaryotes, which
are small and lack a nucleus and organelles, and eukaryotes, which are larger
and have both a nucleus and organelles. Viruses are not cellular and are,
therefore, sometimes called particles rather than organisms. They are included in
microbiology because of their small size and close relationship with cells.
Macromolecules are very large organic molecules (polymers) usually built up by
polymerization of smaller molecular subunits (monomers). Carbohydrates are
biological molecules whose polymers are monomers linked together by glycosidic
bonds. Their main functions are protection and support (in organisms with cell
walls), and also nutrient and energy stores. Lipids are biological molecules, such
as fats, that are insoluble in water. Their main functions are as cell components,
and nutrient and energy stores.
Proteins are biological molecules whose polymers are chains of amino acid
monomers linked together by peptide bonds. Proteins are called the “shapers of
life” because of the many biological roles they play in cell structure and cell
metabolism. Protein structure determines protein function. Structure and shape
are dictated by amino acid composition and by the pH and temperature of the
protein’s immediate environment. Nucleic acids are biological molecules whose
polymers are chains of nucleotide monomers linked together by phosphate–
,pentose sugar covalent bonds. Double-stranded nucleic acids are linked together
by hydrogen bonds. Nucleic acids are information molecules that direct cell
metabolism and reproduction. Nucleotides such as ATP also serve as energy-
transfer molecules in cells. As the atom is the fundamental unit of matter, so is
the cell the fundamental unit of life.
The taxonomic system has three primary functions: naming, classifying, and
identifying species. The major groups in the most advanced taxonomic system
are (in descending order): domain, kingdom, phylum or division, class, order,
family, genus, and species.
Pre-Class Ideas for Chapter 1
Below are suggested activities to assign before covering the material of Chapter
One in class. The activities are designed to provide opportunities for students to
engage with the topics prior to class. Some activities also have students
preparing materials that will enable students to teach one another in class.
1. Students review the definition of “microbiology” prior to class and create a
worksheet that introduces the different forms of microorganisms. Students
exchange and complete worksheets in class.
2. Students create a list of diseases they believe are caused by
microorganisms and the type of microorganism that causes the disease
(bacteria, virus, etc.). Student then compare this list with the information
described in Section 1.1, “Microbes Harming Humans”, and list any new
observations.
3. Students, in groups or as individuals, are assigned one of the following:
Figure 1.1, Table 1.1, Figure 1.4, Table 1.4, Figure 1.8, Figure 1.9, Figure
1.10, Figure 1.11, Figure 1.12, Figure 1.13. Students are required to
create a short presentation to teach the class the material contained within
the figures and tables.
4. Students write a brief statement as to why evolution is considered a
theory.
5. Using Section 1.2, “Microbes in History”, as a guide, each student selects
a scientific contribution in the field of medical microbiology and reports to
the class a current example of how this contribution continues to affect
patient care.
6. Students are required to research protocols in medicine during the 1800s
and a list is created based on each student’s findings.
7. Prior to class, students create a list of characteristics that define a “cell”.
, 8. Assign each student one of the major biochemical groups to research with
a focus on the monomer, basic structure, and role of the macromolecule in
life. Students create a picture or model to present to the class.
9. Provide students a list of some microorganism names: Escherichia coli,
Staphylococcus aureus, and so on. Ask student to find meanings behind
the names.
Activities Associated with Learning Objectives for Chapter 1
Lecture Suggestions and Guidelines for Section 1.1
1. Introduce students to the study of microbiology and how this particular
course will focus on a specific area of microbiology—primarily infectious
diseases.
2. Emphasize that microbes have both beneficial and harmful effects in
relation to humans.
3. Introduce the idea that some diseases, such as stomach ulcers, may have
a microbial component.
4. Emphasize the different forms of microorganisms, and perhaps begin to
introduce the idea of how this is related to treatment of different infectious
diseases.
5. Help students understand the relationship between bacteria, archaea, and
eukaryotes.
In-Class Activities for Section 1.1
1. Create a drawing comparing the size of various microorganisms.
2. Create a “Pro/Con” chart elucidating the positive and negative effects of
microbes on human life.
3. Create a discussion board listing the products that would no longer be
available to humans if microorganisms became extinct.
, 4. Compare and contrast similarities and differences between
microorganisms. Which microorganisms are most closely related to
human cells?
5. Have students discuss why viruses are referred to as “particles” rather
than as “organisms”.
6. Create a chart listing tissues of the body and some ideas relating to the
microbiota of the tissues.
Additional Research Issues for Section 1.1
1. Research how genetic recombination is currently affecting human lives.
2. Research emerging infectious diseases.
Critical Thinking Issues for Section 1.1
1. How do microbes use humans and how do humans use microbes? Who
has the advantage?
2. Many people have a fear of microorganisms or “germs”. Why do you think
this is a realistic fear? Why do you think such a fear may be unrealistic?
Lecture Suggestions and Guidelines for Section 1.2
1. Relate to students how prior findings in microbiology are still being applied
today.
2. Demonstrate how new findings in microbiology are changing our current
understanding of microbes and disease.
In-Class Activities for Section 1.2
1. Create a timeline showing the major scientists and discoveries in
microbiology. Mark those discoveries that are still being applied today.
2. Given a scenario of a patient walking into an Emergency Department with
a suspected infectious disease, list some procedures and protocols used
in relation to the patient that are based on discoveries made during the
Golden Age of Microbiology.
Additional Research Issues for Section 1.2
1. Research biofilms and present a case underlining how their formation may
be impacting the treatment of diseases.
2. Provide information on the basic format of the Human Microbiome Project.
Critical Thinking Issues for Section 1.2
Introduction to Microbes and Their Building Blocks
Microorganisms are defined as “living organisms too small to be seen with the
naked eye.” Members of this huge group of organisms are prokaryotes (bacteria
and archaea), algae, protozoa, fungi, parasitic worms (helminthes), and viruses.
Microorganisms live nearly everywhere and influence many biological and
physical activities on earth. There are many kinds of relationships between
microorganisms and humans; most are beneficial, but some are harmful.
Microbes are crucial to the cycling of nutrients and energy necessary for all life
on earth.
Humans have learned how to manipulate microbes to do important work for them
in industry, medicine, and in caring for the environment. In the past 120 years,
microbiologists have identified the causative agents for many infectious diseases.
They have discovered distinct connections between microorganisms and
diseases whose causes were previously unknown. The microscope made it
possible to view microorganisms and thus to identify their widespread presence,
particularly as agents of disease. Medical microbiologists developed the germ
theory of disease and introduced the critically important concept of aseptic
technique to control the spread of disease agents. Our current understanding of
microbiology is the cumulative work of thousands of microbiologists, many of
whom literally gave their lives to advance knowledge in this field.
Excluding the viruses, there are two types of microorganisms: prokaryotes, which
are small and lack a nucleus and organelles, and eukaryotes, which are larger
and have both a nucleus and organelles. Viruses are not cellular and are,
therefore, sometimes called particles rather than organisms. They are included in
microbiology because of their small size and close relationship with cells.
Macromolecules are very large organic molecules (polymers) usually built up by
polymerization of smaller molecular subunits (monomers). Carbohydrates are
biological molecules whose polymers are monomers linked together by glycosidic
bonds. Their main functions are protection and support (in organisms with cell
walls), and also nutrient and energy stores. Lipids are biological molecules, such
as fats, that are insoluble in water. Their main functions are as cell components,
and nutrient and energy stores.
Proteins are biological molecules whose polymers are chains of amino acid
monomers linked together by peptide bonds. Proteins are called the “shapers of
life” because of the many biological roles they play in cell structure and cell
metabolism. Protein structure determines protein function. Structure and shape
are dictated by amino acid composition and by the pH and temperature of the
protein’s immediate environment. Nucleic acids are biological molecules whose
polymers are chains of nucleotide monomers linked together by phosphate–
,pentose sugar covalent bonds. Double-stranded nucleic acids are linked together
by hydrogen bonds. Nucleic acids are information molecules that direct cell
metabolism and reproduction. Nucleotides such as ATP also serve as energy-
transfer molecules in cells. As the atom is the fundamental unit of matter, so is
the cell the fundamental unit of life.
The taxonomic system has three primary functions: naming, classifying, and
identifying species. The major groups in the most advanced taxonomic system
are (in descending order): domain, kingdom, phylum or division, class, order,
family, genus, and species.
Pre-Class Ideas for Chapter 1
Below are suggested activities to assign before covering the material of Chapter
One in class. The activities are designed to provide opportunities for students to
engage with the topics prior to class. Some activities also have students
preparing materials that will enable students to teach one another in class.
1. Students review the definition of “microbiology” prior to class and create a
worksheet that introduces the different forms of microorganisms. Students
exchange and complete worksheets in class.
2. Students create a list of diseases they believe are caused by
microorganisms and the type of microorganism that causes the disease
(bacteria, virus, etc.). Student then compare this list with the information
described in Section 1.1, “Microbes Harming Humans”, and list any new
observations.
3. Students, in groups or as individuals, are assigned one of the following:
Figure 1.1, Table 1.1, Figure 1.4, Table 1.4, Figure 1.8, Figure 1.9, Figure
1.10, Figure 1.11, Figure 1.12, Figure 1.13. Students are required to
create a short presentation to teach the class the material contained within
the figures and tables.
4. Students write a brief statement as to why evolution is considered a
theory.
5. Using Section 1.2, “Microbes in History”, as a guide, each student selects
a scientific contribution in the field of medical microbiology and reports to
the class a current example of how this contribution continues to affect
patient care.
6. Students are required to research protocols in medicine during the 1800s
and a list is created based on each student’s findings.
7. Prior to class, students create a list of characteristics that define a “cell”.
, 8. Assign each student one of the major biochemical groups to research with
a focus on the monomer, basic structure, and role of the macromolecule in
life. Students create a picture or model to present to the class.
9. Provide students a list of some microorganism names: Escherichia coli,
Staphylococcus aureus, and so on. Ask student to find meanings behind
the names.
Activities Associated with Learning Objectives for Chapter 1
Lecture Suggestions and Guidelines for Section 1.1
1. Introduce students to the study of microbiology and how this particular
course will focus on a specific area of microbiology—primarily infectious
diseases.
2. Emphasize that microbes have both beneficial and harmful effects in
relation to humans.
3. Introduce the idea that some diseases, such as stomach ulcers, may have
a microbial component.
4. Emphasize the different forms of microorganisms, and perhaps begin to
introduce the idea of how this is related to treatment of different infectious
diseases.
5. Help students understand the relationship between bacteria, archaea, and
eukaryotes.
In-Class Activities for Section 1.1
1. Create a drawing comparing the size of various microorganisms.
2. Create a “Pro/Con” chart elucidating the positive and negative effects of
microbes on human life.
3. Create a discussion board listing the products that would no longer be
available to humans if microorganisms became extinct.
, 4. Compare and contrast similarities and differences between
microorganisms. Which microorganisms are most closely related to
human cells?
5. Have students discuss why viruses are referred to as “particles” rather
than as “organisms”.
6. Create a chart listing tissues of the body and some ideas relating to the
microbiota of the tissues.
Additional Research Issues for Section 1.1
1. Research how genetic recombination is currently affecting human lives.
2. Research emerging infectious diseases.
Critical Thinking Issues for Section 1.1
1. How do microbes use humans and how do humans use microbes? Who
has the advantage?
2. Many people have a fear of microorganisms or “germs”. Why do you think
this is a realistic fear? Why do you think such a fear may be unrealistic?
Lecture Suggestions and Guidelines for Section 1.2
1. Relate to students how prior findings in microbiology are still being applied
today.
2. Demonstrate how new findings in microbiology are changing our current
understanding of microbes and disease.
In-Class Activities for Section 1.2
1. Create a timeline showing the major scientists and discoveries in
microbiology. Mark those discoveries that are still being applied today.
2. Given a scenario of a patient walking into an Emergency Department with
a suspected infectious disease, list some procedures and protocols used
in relation to the patient that are based on discoveries made during the
Golden Age of Microbiology.
Additional Research Issues for Section 1.2
1. Research biofilms and present a case underlining how their formation may
be impacting the treatment of diseases.
2. Provide information on the basic format of the Human Microbiome Project.
Critical Thinking Issues for Section 1.2
