Chapter 1

completed: 1.1

What is microbiology?

• Specialized area of biology studying organisms too small to see without magnification.

• These organisms are called microorganisms or microbes.

• Most microorganisms are harmless; only a small minority cause disease.

T or F: Most microorganisms are harmful to humans and animals.

False. Most microorganisms are harmless; only a small minority cause disease.

T or F: Microorganism and microbe are synonymous terms.

True

Name an example of a common colloquial term used to refer to microorganisms.

•  germs

• bugs

• agents
  
  

List and only list the 7 types of microorganisms.

1. Bacteria

2. Archaea

3. Algae

4. Fungi

5. Protozoa

6. Helminths

7. Viruses

Name the 7 types of microorganisms and for each, determine if it is:

• Cellular or Acellular

• Eukaryotic or Prokaryotic

(Hint:

Cellular Microorganisms

1. Bacteria (Prokaryotic, Unicellular)

2. Archaea (Prokaryotic, Unicellular)

3. Algae (Eukaryotic, Both —> most unicellular, some multicellular)

4. Fungi (Eukaryotic, Both —> yeast = unicellular & mold = multicellular)

5. Protozoa (Eukaryotic, Unicellular)

6. Helminths (Eukaryotic, Multicellular)

Acellular Microorganisms

7. Archaea (not applicable)

Cellular v.s. Acellular

• Cellular: composed of cells (bacteria, archaea, fungi, protozoa, helminths).
  
  

• Acellular: not made of cells (viruses, prions).

Eukaryotic vs Prokaryotic

Eukaryotic: has a nucleus and organelles, usually bigger (animals, plants, fungi).

Prokaryotic: no nucleus or organelles, usually smaller (bacteria, archaea).

“Helminths are technically not microorganisms'“.

Explain the meaning of the statement above.

• Helminths are not technically microorganisms (macroscopic when full-grown)

• But is still studied in microbiology because:

  (a) their eggs and larvae are microscopic

  (b) they cause human infections

Compare the relative sizes of the diff types of microorganisms.

• Prion: Smallest (~10 nanometres)

• Viruses: Smallest (~100 nanometres)

• Bacteria: Mid-sized (~1000 nanometers or ~1 micrometer)

• Eukaryotic cells: Largest (up to millimeters)

What major factor impacts how microorganisms are studied w/in science lab?

Size

“ The Nature of microorganisms can make them both easy & hard to study.”

Explain your answer.

• Easy bc they reproduce quickly → easy to grow large populations in labs fast

• Hard bc we can’t see them directly → we rely on indirect means of analyzing them + microscopes  

Name some of the general aspects of microorganisms that microbiologists study.

• Structure, function, growth, physiology
  

• Genetics, taxonomy, evolutionary history
  

• Interactions with hosts & environment
  

• Applications in medicine, agriculture, and industry

Medical Microbiology

(a) Focus Area

(b) Real-World Application

(a) Focus Area

Examining disease-causing microbes (in humans & animals)

(b) Real-World Application

Diagnosing & preventing infections  Major institution conducting medical microbiology is the Centres for Disease Control and Prevention (CDC)

Public Health Microbiology & Epidemiology

(a) Focus Area

(b) Real-World Application

(a) Focus Area

Monitoring & controlling disease spread in populations

(b) Real-World Application

• Tracking outbreaks, statistical modelling 

• Institutions involved include: 

  • U.S. Public Health Service (USPHS)

  • CDC

  • WHO

Immunology

(a) Focus Area

(b) Real-World Application

(a) Focus Area

• Body’s defense mechanisms against infections 

  (the protective substances and cells  the human/animal body produces in response to infection & cancer)

(b) Real-World Application

Vaccine development, immune response

Industrial Microbiology

(a) Focus Area

(b) Real-World Application

(a) Focus Area

• Ensuring & optimizing safety of food & water for consumption

• Use of biotechnology + microbial metabolism to arrive at desired product (e.g. bread making or gene therapy)

• Microbes used to create:

  • Amino acids

  • Beer

  • Drugs

  • Enzymes 

  • Vitamins

(b) Real-World Application

Food, beverages, biofuels, pharmaceuticals

Agricultural Microbiology

(a) Focus Area

(b) Real-World Application

(a) Focus Area

• Relationships b/w microbes & farm animals & crops. 

• Plant diseases & soil fertility 

• Infectious disease w/in animals

(b) Real-World Application

Crop yield improvement, disease

Environmental Microbiology

(a) Focus Area

(b) Real-World Application

(a) Focus Area

• Study effect of microbes on diverse habitats

• Explores how microbes can be used for plant health & soil fertility 

Aquatic microbiology	Study of microbes in earth’s surface water
Soil microbiology	Study of microbes in terrestrial parts of planet
Geomicrobiology	Study of microbes in earth’s crust
Astrobiology (AKA exobiology)	Search for/study of microbial & other life in places off our planet

(b) Real-World Application

Pollution control, nutrient cycling

Aquatic Microbiology

• Sub-area under environmental microbiology

• Study of microbes in earth’s surface water

Soil Microbiology

Study of microbes in terrestrial parts of the planet

Geomicrobiology

Study of microbes in earth’s crust

Astrobiology (AKA exobiology)

Search for/study of microbial & other life in places off our planet

Name the 2 branches of microbiology the CDC (Centre of Disease Control and Prevention) are heavily involved with.

1. Medical microbiology

2. Public health microbiology & epidemiology

Which instituitions are heavily involved with public health microbiology & epidemiology?

1. US Public Health Service (USPHS)

2. Centre for Disease Control and Prevention (CDC)

3. World Health Organization (WHO)

Provide a summarized explanation of the role & impact of microbes on the earth.

• Microbes have shaped Earth’s environments and contributed to the evolution of life for billions of years.
  
  

• They drive essential processes like photosynthesis (producing most of Earth’s oxygen), decomposition (recycling nutrients), and gas production (CO₂, methane, nitrous oxide) that regulate the planet’s temperature.
  
  

• Microbes form vital relationships with plants and animals—helping with nutrient absorption, digestion, and disease protection.
  
  

• Because they are everywhere and highly adaptable, microbes are essential for maintaining ecosystems and making life on Earth possible.

Explain the theory of evolution and why it is called a theory.

• Evolution is the scientific principle that living organisms gradually change over time through adaptation to their environments.

• Helpful traits are preserved & passed to future generations

• Harmful traits often disappear.

• Called a theory bc in science a theory is not speculation but a well-tested, evidence-based explanation.

• Theory of evolution is supported by extensive research

Descirbe the 2 general/major roles microbes play in the crucial role in development of the Earth.

1. Shaping earth’s diverse array of habitats/ecosystems

2. Contributing to evolution of earth’s various life forms

The adaptation of single-celled organisms over billions of years, which eventually gave rise to today’s diverse life forms — is a key example of what?

Evolution

When scientists look for signs of life on other planets — where do they start? Why?

Bc of role microbes played in early development of life on Earth → scientists searching for life on other planets start by looking for signs of microorganisms

T or F: The complete and actual events that led to life forming on our planet are not yet fully understood.

True

Briefly describe the current Theory of Evolution.

• Shortly after Earth formed, the first ancient cells emerged.

• From these primitive cells, bacteria and archaea—single-celled organisms without a nucleus (akaryotes)—developed.

• For over a billion years, these eukaryotes were the only cell types on Earth, adapting to environmental changes

• Eventually, eukaryotes—cells with a true nucleus and greater complexity—emerged 

(a) What does “Eukary-” mean?

(b) How does this relate to classifying cells as eukaryotic vs. akaryotic?

(a) ‘Eukary’ = true nucleus

(b) Cells are categorized as…

• Eukaryotic —> have nucleus (+ membrane-bound organelles)

• Prokaryotic —> no nucleus (or membrane-bound organelles)

List the 3 major cell types.

1. Bacteria

2. Archaea

3. Eukaryotes

The first cells on earth appeared almost _________ years ago.

The first cells on earth appeared almost 4 billion years ago.

T or F: Microbes are essential for all life on Earth.

True

Why shouldn’t humans aim to eliminate bacteria?

• Bc bacteria predates animals by billions of years

• This demonstrates their resilience & adaptability to catastrophic environmental changes

• Meaning they must be vital to Earth’s ecosystems

“Bacteria are very ubiquitous”

Explain what this means.

“ubiquitous” meaning microbes can be found nearly everywhere on Earth

Why isn’t the impact of microbes as obvious as that of larger plants and animals?

Because microbes are microscopic so, their actions and effects are less visible.

Traits in organisms that favour survival (withstand adaptation) tend to be…

preserved & passed on to future generations of organisms

Traits in organisms that hinder survival (withstand adaptation) tend to be…

diminished or lost overtimne

In science, what does it mean when an idea is called a “theory”?

• It t has been thoroughly tested over many years

• Has not been disproven.

In general, what key role do microbes play in ecosystems?

They play key role in flow of energy & food w/in ecosystems .

Oxygenic Photosynthesis

Plants converting CO₂ + light —> organic material, while releasing oxygen

T or F: Another entity performed photosynthesis before plants.

True

Bacteria performed/invented photosynthesis before plants

What type of photosynthesis did bacteria first develop?

Anoxygenic photosynthesis (did not produce oxygen).

What type of photosynthesis evolved from anoxygenic photosynthesis?

Oxygenic photosynthesis.

T or F: Plants and microorganisms can both perform oxygenic photosynthesis.

Why was the emergence of oxygenic photosynthesis significant?

• Oxygenic photosynthesis more efficient at extracting energy from sunlight.

• Oxygen production enabled aerobic respiration and the formation of ozone, driving species diversification.

In the current age, photosynthetic microorganisms _____________ & _____________ perform about ______ of Earth’s photosynthesis.

In the current age, photosynthetic microorganisms bacteria & algae perform about 70% of Earth’s photosynthesis.

Where is most oxygen produced?

Atmosphere

Define “Decomposition”

A: The breakdown of dead matter and wastes into simple compounds that are naturally recycled in the environment.

Briefly describe the process of decomposition step-by-step.

• Process of Decomposition: 

  • Death occurs

  • Bacteria decomposes human/animal corpse by converting tissues into liquids & gases

  • Chemicals are released (e.g. hydrogen sulfide) causing the pungent smell infamously associated w/ decomposition 

How did bacteria change Earth’s atmosphere?

They transformed it from oxygen-free to oxygen-rich.

They transformed it from oxygen-free to oxygen-rich.

What did oxygen production enable on Earth?

• Aerobic respiration

• Ozone formation

• Species diversification.

Which type of microorganism transformed Earth’s atmosphere from oxygen-free to oxygen-rich billions of years ago?

Bacteria

(a) How do microorganisms influence the structure and content of soil, water, and atmosphere?

(b) Provide two specific examples of this.

(a) Microorganisms drive the structure and content of soil, water, and atmosphere by recycling nutrients, producing gases that regulate climate, and forming essential relationships with plants and animals.

(b) Examples:

1. Bacteria transformed Earth’s atmosphere from oxygen-free to oxygen-rich —> enabling aerobic respiration AND formation of ozone.

2. Photosynthetic microorganisms (bacteria and algae) perform about 70% of Earth’s photosynthesis today —> producing most of the oxygen in the atmosphere.