CH. 1 | The Microbial World and You

1 - 1 List several ways in which microbes affect our lives

Microbes (Microorganism) - Minute living things that cannot be seen with the naked eye + includes bacteria, fungi, protozoa, microscopic algae, and viruses

Microbes is important in both life itself and in the environment. For instance, it forms the basis of the food chain in oceans and lakes, it breaks down wastes, it can play a certain role in photosynthesis, and is involved in the food industry (due to enzyme manipulation).

It can also be used in the synthesis of chemical products containing vitamins, organic acids, enzymes, drugs, etc.

Describe some of the beneficial and destructive actions of microbes

Benefits

• Environmental
  → Photosynthetic microbes → oxygen
  → Food webs
  → Nutrient cycling
  → Bioremediation
  → Important component in the food web of fresh water and marine environments
  
  

• Food
  → Bread , Wine , Cheese , Yogurt
  
  

• Chemicals
  → Acetone
  → Production of vinegar & alcoholic beverages
  
  

• Health / Science
  → Antibiotics
  → Research Labs
  
  

Destructives

• Cause disease

• If there’s an overgrowth of microbes in spoiled food or liquid, it can cause a change in smell, taste, and texture.. Which can then lead to
  → Fermentative bacteria

1 - 2 Define microbiome, normal microbiota, and transient microbiota.

Microbiome - All the microorganisms in an environment / human body

→ lives stable - without typically causing disease

Normal microbiota - The microorganisms that colonize a host without causing disease

• Prevents the growth of pathogenic microbes

• Trains the immune system to distinguish pathogens

• Nutrition
  
  

Transient microbiota - The microorganisms that are present in an animal for a short time without causing a disease

Pathogen

• Disease causing microorganism

What percentage of all cells in the human body are bacterial cells?

40 trillion bacterial cells

1 - 3 Recognize the system of scientific nomenclature that uses two names: a genus and a specific epithet.

Scientific nomenclature - Used for naming / Organism is referred to by both the genus & specific epithet + either underlined or italicized

• Designed by Carl Linneaus

Genus - 1st name & is always capitalized

Specific epithet - Species name, and is not capitalized

Distinguish a genus from a specific epithet.

In the name Escherichia coli, coli represents the:

species name / specific epithet

Difference between prokaryotes and eukaryotes

Prokaryotes

• Prokaryotes are unicellular organisms that include bacteria and archaea. They are structurally simpler, smaller, lack a nucleus, and lack membrane-bound organelles
  
  

Eukaryotes

• Eukaryotes are organisms whose cells have a true nucleus + other organelles, and are enclosed within membranes

1 - 4 Differentiate the major characteristics of each group of microorganisms

Bacteria

• 1 of the domains

• Prokaryotes

• Single-celled (unicellular) organisms (each bacterium contains one cell)

• Appear in types of shapes: Bacillus (rodlike) Coccus (spherical), and Spiral (curved), etc

• Cell wall: Peptidoglycan

• Reproduces by binary fission (dividing into 2 equal cells)

• Motility is seen by flagella, etc

• Absorbs organic or inorganic material (explains how they get energy)

• Displays the greatest metabolic diversity
  
  

Archaea

• 1 of the domains

• Prokaryotes

• Single-celled (unicellular) organisms

• Have cell walls, but lack/do not have peptidoglycan

• Divided into 3 main groups: Methanogens, Extreme halophiles, & Extreme thermophiles

• Not known to cause disease in humans
  
  

Fungi

• Eukaryotes

• May be unicellular or multicellular (yeasts/mushrooms)
  → Bimorphic fungi (^ both depending on the environment)

• Cell wall: Chitin

• Cannot carry out photosynthesis

• Most typical form of fungi is molds

• Can reproduce sexually or asexually

• Obtain nourishment by absorbing organic material from their environment

• Mycelia/Mycelium (hyphae filaments) form the main body of a fungus
  
  

Protozoa

• Eukaryotes

• Single-celled (unicellular) organisms

• Motility is seen by pseudopods, flagella, or cilia
  → flagella are appendages that allow locomotion in bacteria

• Contains a variety of shapes

• Live either as free entities or as parasites (that absorb organic compounds from their environment)

• Usually chemoheterotrophic → light as a source of energy & carbon dioxide to produce sugars

• Reproduce sexually or asexually
  
  

Algae

• Photosynthetic eukaryotes

• May be unicellular, filamentous, or multicellular but lacks the tissues found in plants

• Cell walls: Cellulose (carbohydrate)

• Motility is seen by flagellated swimming

• Abundant in freshwater, saltwater, soil & in plants

• Reproduces sexually or asexually

• Photosynthesis benefits | uses sunlight to create their own food
  
  

Viruses

• Acellular

• Structurally, contains 1 type of nucleic acid; either DNA or RNA
  → surrounded by a protein coat

• Reproduces only by using the cellular machinery of other organisms | Cannot reproduce outside a host cell

• Considered to be living only when they multiply within host cells they infect

• Considered not because they are inert outside living hosts
  
  

Multicelluar Animal Parasites

• Animal parasites are eukaryotes

• Multicellular

• 2 major groups: Flatworms & Roundworms / Helminths

• Nutrition: ingest through a mouth

• Reproduces sexually or asexually

Which groups of microbes are prokaryotes? Which are eukaryotes?

Prokaryotes

• Bacteria

• Archaea
  
  

Eukaryotes

• Fungi

• Protozoa

• Algae

• Multicellular Animal Parasites
  
  

Viruses - Neither because they are acellular

1 - 5 List the 3 domains.

• Bacteria

• Archaea

• Eukarya

Viruses do NOT follow under any of these categories, (including prokaryotes & eukaryotes)

What are the 3 domains?

• Bacteria (cell walls contain a protein–carbohydrate complex called peptidoglycan)
  
  

• Archaea (cell walls, if present, lack peptidoglycan)
  
  

• Eukarya, which includes the following:

  • Protists (slime molds, protozoa, and algae)

  • Fungi (unicellular yeasts, multicellular molds, and mushrooms)

  • Plants (mosses, ferns, conifers, and flowering plants)

  • Animals (sponges, worms, insects, and vertebrates)
    
    

Archea & Eukarya are more closely related as opposed to Bacteria (because of their genetic and informational mechanisms)

1 - 6 Explain the importance of observations made by Robert Hooke & Van Leeuwenhoek.

Robert Hooke given his improved microscope was able to see individual cells. However, it lacked the resolution to see microbes clearly.

• Led to the development of the cell theory

On the other hand, Van Leuuwenhoek was the first to observe live microorganisms through magnifying lenses

• Between 1673 & 1723, he wrote about “animalcules”

• Depicted drawings of organisms he found in different environments / atmospheres

What is the cell theory?

All living organisms are composed of cells and arise from preexisting cells

Viruses are NOT considered living because they are acellular and are distinct from other microbe groups

1 - 7 Compare spontaneous generation and biogenesis

Spontaneous generation

• The idea that life could arise spontaneously from nonliving matter
  
  

Biogenesis

• The theory that living cells arise only from preexisting cells

• Life → Life

→ Issue was later resolved by Louie Pasteur in 1861

What evidence supported spontaneous generation?

The idea of:
Flies emerging from manure / Maggots arising from decaying corps

John Needham:
After boiling chicken & corn broth, the cooked solutions were apparent with microorganisms. Which garnered his reasoning that microbes developed spontaneously from the fluids (DEBUNKED)

1 - 8 Identify the contributions to microbiology made by Pasteur.

• Argued that microbes in the air were the agents responsible for contaminating nonliving matter

• Demonstrated that microbes are responsible for food spoilage, further encompassing the connection between microbes and disease

• His experiments & observations provided the basis of aseptic techniques

• Pasteur created an experiment that permitted air to enter but the special shape of the flask’s opening prevented airborne bacteria from contaminating the broth.

How was spontaneous generation disproved?

According to Pasteurs’ swan-neck chicken broth experiment, he demonstrated that microbes were present in nonliving matter (air , liquids , solids). Which further invalidated the hypothesis of spontaneous generation.

NO GROWTH because all the microbes got trapped, the broth ended up remaining sterile → Further convincing people that microorganisms had to have come from pre-existing organisms → Further debunking spontaneous generation and supporting biogenesis

1 - 9 Explain how Pasteur’s work influenced Lister and Koch.

Louis Pasteur showed that tiny microorganisms cause disease.
- Started the idea of microbial growth

• His idea led Joseph Lister to use phenol (carbolic acid) in surgery to kill germs and keep wounds clean, which greatly reduced infections.
  → Used as the first disinfectant

• Robert Koch later expanded on this by developing Koch’s postulates, a set of criteria/steps for proving that a specific germ causes a specific disease, further strengthening the germ theory.

• A given pathogen can cause disease

Summarize in your own words the germ theory of disease.

The principle that microorganisms cause disease.

1 - 10 Identify the importance of Koch’s postulates.

Koch’s postulates were criteria used to determine the causative agent of infectious diseases.

• To provide a scientific framework that a specific microorganism causes a specific infectious disease

• He created very specific steps that link a particular pathogen to a specific disease as the causative, or etiologic, agent

1 - 11 Identify the importance of Jenner’s work.

Edward Jenner’s observations led to the concept of immunity / protection from infection through previous exposure to a pathogen.

• First vaccine to be developed (1796)

• This was due to individuals being previously sickened with cowpox and did not develop smallpox infections even after being injected with it (cowpox immunity against smallpox)

• Trusted that the body produced agents that effectively overcame a disease-causing microbe

1 - 12 Identify the contributions to microbiology made by Ehrlich and Fleming.

Paul Ehrlich introduced an arsenic-containing chemical called salvarsan (his magic bullet) to treat syphilis (1910).

• His magic bullet: selective toxicity, should harm a pathogen, and not harm the host
  
  Alexander Fleming observed that the Penicillium fungus inhibited (prevented) the growth of a bacterial culture. He named the active ingredient penicillin (1928).

• First true antibiotic to be developed (1928)

• Penicillin has been used clinically as an antibiotic since the 1940s.

• antimicrobials

• However, the usefulness of an antibiotic can be hampered due to the emergence of antibiotic-resistant bacteria

• Present; more ABX (antibiotics) were discovered and being used

1 - 13 Define bacteriology, mycology, parasitology, immunology, and virology.

Bacteriology

• The scientific study of prokaryotes, including bacteria and archaea

Mycology

• The study of fungi

Parasitology

• The study of protozoa and worms

Virology

• The study of viruses (structure , life cycle , evolution , classification , etc)

1 - 15 List at least 4 beneficial activities of microorganisms

• Recycling vital elements

• Sewage treatment: Using microbes to recycle water

• Bioremediation: Using Microbes to clean up pollutants

• Insect Pest Control by Microogranisms

Name 2 beneficial uses of bacteria

• Food production through fermentation

• Medicine through the use of antibiotics

1 - 17 Define resistance

The ability to ward off diseases through innate and adaptive immunity.

• Vaccines

• Antibiotics (Helps the body be more resistant)

• Prevent microbes from getting in; immune system

Differentiate normal microbiota and infectious disease.

Normal microbiota

• The microorganisms that colonize a host without causing disease

Infectious disease

• A change in the state of health when a pathogen grows in a host

1 - 18 Define biofilm.

A microbial community that usually forms as a slimy layer on a surface.

• Complex aggregation of microbes

Why are biofilms important?

They can protect your mucous membranes from harmful microbes and are an important food source to aquatic animals.

However, it can also be harmful and cause infections. If it formed/grew on environmental surfaces, or on implants, it would be difficult to remove them

1 - 19 Define emerging infectious disease.

A new or changing disease that is increasing or has the potential to increase in incidence in the near future

• EX; Measles

What factors contribute to the emergence of an infectious disease?

Evolutionary changes in existing organisms, or the spread of known diseases to new geographic areas