Basics of Microbiology

Question 1

What are microorganisms (microbes)?
What are the four common characteristics associated with them?

Answer 1

Life forms too small to be seen by the human eye. Microbe is a term of convenience, microscopic size and being unicellular are not absolute characteristics.

1. Diverse in form/function
2. Inhabit every environment that supports life
3. Many are single-celled, some form complex structures, and some are multicellular
4. Live in microbial communities

Question 2

Microbes are _ and _

Answer 2

Ubiquitous (present, found everywhere) and abundant (existing in large quantities)

Question 3

What are the eight types of microorganisms?

Answer 3

Bacteria, archaea, fungi, protists, algae, viruses, multicellular animal parasites, prions

Question 4

What measurement is used for microorganisms?

Answer 4

Very small units of the metric system are called micrometers (um) and nanometers (nm).

Acellular and unicellular microbes extend over a range of sizes from nanometers to micrometers

Question 5

What does pathogenic mean?

Answer 5

Disease-producing organisms (bacteria, viruses, and other microorganisms can be pathogenic).

Question 6

What does symbiosis mean?

Answer 6

Symbiosis means living together; interaction between two different organisms living in close physical association, typically to the advantage of both.

Question 7

What is the human microbiome and what can it do?

Answer 7

A group of microbes that live stably on or in the human body. They can help maintain good health, prevent growth of pathogenic microbes, and may help train the immune system to discriminate threats.

Question 8

What is the normal microbiota?

Answer 8

The collection of acquired microorganisms on or in a healthy human.
Begin acquiring before birth, more acquired as newborns, may colonize the body indefinitely, may colonize the body fleetingly (making them transient microbiota).

Question 9

What is the transient microbiota?

Answer 9

Microorganisms that colonize the body for a while and then go away.
Microorganisms that are only temporarily found in the human body, and these may include pathogenic microorganisms. Hygiene and diet can alter both the resident and transient microbiota

Question 10

What are prebiotics and what are some examples of them?

Answer 10

Prebiotics are foods (typically high-fiber foods) that act as food for human microflora. Prebiotics are used to improve the balance of these microorganisms.
Examples: Onion, soy beans, asparagus, bananas, leek, bread, artichoke, and garlic.

*Microflora is the community of microorganisms, including algae, fungi, and bacteria that live in or on another living organism or in a particular habitat.

Question 11

What are probiotics and what are some examples?

Answer 11

Probiotics are foods or supplements that contain live microorganisms intended to maintain or improve the “good” bacteria (normal microflora) in the body.
Examples: Aged cheese, bitter chocolate, kefir, sour cream, miso soup, pickles, probiotic milk, and yogurt.

Question 12

Where are microbes found, how abundant are they, and how long have they been around?

Answer 12

Microbes are tiny living things that are all around us. They live in water, soil, and air. The human body is also home to around 40 trillion microbes and 30 trillion body cells. Microbes are very abundant and have been around for around 4 billion years.

Question 13

What are some ways that microbes impact human life and the planet?

Answer 13

• A few are pathogenic (disease-producing): Emerging Infectious Diseases
• Essential to the cycles of nature required for higher life
  forms to exist
• Decompose organic waste
• Generate oxygen by photosynthesis
• Produce chemical products such as ethanol, acetone, and vitamins
• Produce fermented foods such as vinegar, cheese, and
  bread
• Produce products used in manufacturing (e.g., cellulose) and disease treatment (e.g., insulin)
• Beneficial and even essential for human health

Question 14

What is the function of the human microbiome?

Answer 14

The human microbiome is the collection of microbes that live on and within humans. Most species within the microbiome are not harmful and can assist in maintaining human health. An important role of the human microbiome is to fight off other pathogenic microbes as well.

Question 15

What are the three domains in classifying microorganisms?

Answer 15

Bacteria, archaea, and eukarya

Question 16

How are microorganisms named and classified?

Answer 16

By their genus and species
Each organism has two names: the genus and species (specific epithet). They are italicized or underlined. The genus is capitalized and the species is lowercase. The scientific names are latinized and used worldwide, and may be descriptive or may honor a scientist.

Example: Escherichia coli Named after the discoverer, Theodor Escherich and describes the bacteriums habitat (the large intestine or colon).
Example:Staphylococcus aureus Describes the clustered (staphylo-) spherical (cocci) cells, and the gold-colored (aureus) colonies.

Question 17

What are the seven major types of microbes?

Answer 17

Prions, viruses, bacteria, protists, unicellular algae, fungi, and helminths.

Question 18

What is commensalism (symbiosis type)?

Answer 18

One organism benefits and the other is unaffected (an example is bacteria on the skin).

Question 19

What is mutualism (symbiosis type)?

Answer 19

Both organisms benefit (an example is gut bacteria).

Question 20

What is parasitism (symbiosis type)

Answer 20

One organism benefits and the other is harmed.

Question 21

What are the differences between normal and transient microbiota?

Answer 21

Normal microbiota is always present on or in the body. Transient microbiota is not always present and most of the time is pathogenic.

Question 22

Taxonomy

Answer 22

Science of classifying living species based on shared characteristics.

Question 23

What is the bacteria, archaea, and eukarya naming system based on?

Answer 23

16s rRNA gene

Question 24

What do cells need to be classified as a cell?

Answer 24

A cell membrane, DNA, and ribosomes.

Question 25

What microorganisms are NOT cells?

Answer 25

Viruses and prions.

viruses = genetic info and protein coat
prions = misfolded protein

Question 26

True or False, all strains are variants, but not all variants are strains.

Answer 26

True

Question 27

Define strain.

Answer 27

Different isolates of the same microbe with different characteristics.

Question 28

Define Variants.

Answer 28

Differs from the original wild-type, genetically.

Question 29

Define species.

Answer 29

The type of microbiota.

Question 30

What are the six characteristics of prions?

Answer 30

1.) NOT alive
2.) Infectious misfolded proteins
3.) Lack of DNA and RNA
4.) Exist normally as harmless proteins
5.) Abnormal prions convert normal prion proteins into infectious disease-producing protein
6.) Little known about their biology

Question 31

What are the seven characteristics of viruses?

Answer 31

1.) NOT alive
2.) Can have either RNA OR DNA
3.) Can have an envelope or no envelope
4.) Capsid
5.) Genome + protein coat
6.) Oligate intracellular parasite, needs living cell to replicate
7.) Takes over metabolism of host cell

Envelope = virus steals plasma membrane from their host cell

Question 32

what are the seven characteristics of bacteria?

Answer 32

1.) Unicellular prokaryote
2.) Microscopic (few exceptions)
3.) DNA genome, reproduce by binary fission
4.) Has peptidoglycan cell wall (except mycoplasma does not have cell wall)
5.) Heterotrophic or autotrophic
6.) Essential role in environment
7.) Most are NOT pathogenic

Question 33

What are the six characteristics of archaea?

Answer 33

1.) Prokaryotic
2.) Lack peptidoglycan, made of pseudomuerin
3.) Live in extreme environments
4.) Include methanogens, extreme halophiles, extreme thermophiles
5.) Not pathogenic
6.) Can grow at 120° C

ex. thermal vents on bottom of the ocean

Question 34

What are the five characteristics of protists?

Answer 34

1.) Unicellular Eukaryotes
2.) DNA genome
3.) Classified according to means of locomotion (moves by flagella)
4.) Heterotrophic, some are photoautotrophic
5.) Sexual or asexual reproduction

Common disease of protists = plasmodium that causes maleria

Question 35

What are the five characteristics of algae?

Answer 35

1.) Unicellular OR Multicellular Eurkaryotes
2.) Photosynthetic: produce oxygen and organic compounds
3.) Cellulose cell wall
4.) Primary source of food in oceans
5.) Not infectious, some pathogenic (ex. red tide)

ex. dinoflagellates, diatoms

Question 36

What are the seven characteristics of fungi?

Answer 36

1.) Unicellular (yeast) or Multicellular (mold/mushroom) Eukaryotes
2.) Heterotophic
3.) Chitin cell walls
4.) Significant in food chains
5.) Most are beneficial, some pathogenic or opportunistic
6.) Decomposes
7.) Do not perform photosynthesis

Question 37

What are the eight characteristics of helminths?

Answer 37

1.) Multicellular animal parasites
2.) Eukaryotic
3.) Macroscopic
4.) DNA genome
5.) Sexual reproduction (complex life cycles)
6.) No cell wall
7.) Heterotrophic
8.) Not really microbes, but some are infectious organisms