Foundations pt 1

Question 1

Microorganisms

Answer 1

A diverse group of organisms that exist as free-living single cells OR cell clusters

Question 2

What can a single microbial cell do?

Answer 2

grow, generate energy, reproduce, and evolve independently of other cells

Question 3

What are the 3 domains of life?

Answer 3

1. Bacteria (prokaryotic organisms)
2. Archaea (prokaryotic organisms)
3. Eukarya (contains eukaryotic cells)

Question 4

Are viruses considered a life form?

Answer 4

No

Question 5

Why are microorganisms important?

Answer 5

Life depends on microbial activity.
There is significant biodiversity.
They are 3.5 billion years old and are the first signs of life.

Question 6

Phylogenetic Tree of Life

Answer 6

1. Bacteria
2. Archaea branch from bacteria
3. Eukarya branch from archaea.

Question 7

Koch’s Postulates

Answer 7

Helps us understand that sickness starts with microbes

Question 8

Four Postulates of Koch

Answer 8

1. Microbe is found in all cases of the disease
2. Microbe is isolated from the diseased host and grown in pure culture.
3. The grown microbe is injected into a healthy organism, the host will become sick with the same disease.
4. Isolate the same strain from the new sick host.

Question 9

Germ Theory

Question 10

Winogradsky Column

Answer 10

A model wetland ecosystem containing a variety of nutrient sources and an inoculum of mud that supports the growth of a wide variety of bacteria.

Question 11

How is the winogradsky column organized?

Answer 11

The top most layer is exposed the most to oxygen. This is where aerobic microbes are found. As you go down the column the amount of oxygen supply decreases leading you to find anaerobic organisms and other types of organisms. (microaerophillic, etc)

Question 12

If I want a bacterial species with certain metabolic properties how can I isolate them?

Answer 12

Selective Culture Medium
Start with an environmental sample that contains a wide variety of microbes. Sample it into a small inoculum. This medium contains certain nutrients, grown at a specific temperature and lighting to only allow the wanted microbe to grow. This process is repeated many times and genome sequencing is used to confirm the correct microbe was grown.

Question 13

How can I grow microbes in the lab?

Answer 13

1. Closed system: (inn and out) Nutrients are not renewed and waste is generated by the microbes. Yields a characteristic growth curve.
2. Open system: (continuous growth)
   Nutrients are added and waste is removed simultaneously. Also called a continuous culture.

Question 14

How does bacteria population grow?

Answer 14

Exponentially. Each individual bacteria can produce 2 offspring.

Question 15

Generation time

Answer 15

The time it takes for a bacteria population to double. Can range from minutes to hours. (E coli. can divide every 30 min or faster)

Question 16

Heterotrophs

Answer 16

Cells that require an organic C source such as glucose, fumarate, acetate.

Question 17

Autotrophs

Answer 17

Cells that can get C from CO2 and can perform carbon fixation. (plants)

Question 17

Microaerophiles

Answer 17

Microbes that live in places where oxygen concentration is low. Deeper in lakes for example.

Question 17

Obligate Aerobes

Answer 17

Microbes that must use O2 as a terminal electron accepter in respiration.

Question 17

Aerotolerant Anaerobes

Answer 17

Ignore the presence of oxygen. Neither benefits or diminishes in the presence of oxygen.

Question 17

Nitrogen-Fixing Bacteria

Answer 17

Microbes that can convert atmospheric N2 to NH4+ and assimilate it into cellular structures.

Question 18

Facultative Anaerobes

Answer 18

Microbes that can either use O2 in respiration or other metabolic strategies when no O2 is present. CAN grow faster when oxygen is present.

Question 19

Obligate Anaerobes

Answer 19

Microbes that avoid oxygen because their enzymes will be harmed and they can die.

Question 20

Terms to describe pH levels for microbes

Answer 20

Optimal growth pH: microbes grow best in this condition
minimum growth pH: lowest pH level a microbe can tolerate
maximum growth pH: highest pH level a microbe can tolerate

Question 21

neutrophiles

Answer 21

A microbe that grows with 1-2 pH levels of neutral which is 7.

Question 22

acidophiles

Answer 22

microbes that grow at pH levels of less than 5.55. Optimal growth values are around 3 for many species.

Question 23

alkaliphile

Answer 23

Microbes that have an optimal pH growth at values above 9.

Question 24

High pH effects on DNA

Answer 24

Hydrogen bonds break apart in DNA

Question 25

Basic pH effects on DNA

Answer 25

Lipids are hydrolyzed. A molecule of water is added.

Question 26

Most vulnerable to pH

Answer 26

Proteins at risk for denaturing or losing shape

Question 27

Terms to describe temperature levels for microorganisms

Answer 27

Optimum growth temperature: microbes grow best at this temperature Minimum growth temperature: lowest temperature that microbes can grow Maximum growth temperature: max temperature that a microbe can grow

Question 28

psychrophiles (cold loving)

Answer 28

microbes that grow at 0 degrees celcius and below. Optimal growth temp at 15 degrees C. Don't survive at temps above 20 degrees C. These are decomposers in cold climates.

Question 29

mesophiles (middle loving)

Answer 29

Microbes that can grow at room temperature (20-45 degrees celcius). Mesophiles are human microbiota and pathogens.

Question 30

thermophiles (heat loving)

Answer 30

Grow at optimum temperatures of 50-80 degrees C. Found in hot springs, geothermal soils, compost piles.

Question 31

hyperthermophiles (extreme heat)

Answer 31

Grow at 80-110 degrees C sometimes above to 121. These microbes live in ocean vents. They have optimal growth at temperatures greater than 100.

Question 32

psychographs

Answer 32

organisms that prefer cooler environments from a higher temperature of 25 degrees C to about 4 degrees C. Responsible for the spoilage of refrigerated food.

Question 33

Extreme temperature affects

Answer 33

At low temperatures membranes can lose their fluidity and form ice crystals. Metabolic processes slow down. Proteins become too rigid to catalyze reactions. Heat denatures proteins and nucleic acids.

Question 34

Halophile

Answer 34

Organism that grows in high salt concentrations.

Question 35

Halotolerant Organisms

Answer 35

Tolerate high salty environments. Known to cause food-borne illnesses.

Question 36

Barophiles

Answer 36

Microbes that live in high atmospheric pressure such as at the bottom of the ocean.

Question 37

Microbes that use light

Answer 37

Photoautotrophs and photoheterotrophs use light and convert it to chemical energy to drive metabolic processes. These are photosynthetic active radiation organisms (PAR). These are cyanobacteria, green sulfur bacteria, etc.

Question 38

Chemically Defined Medium

Answer 38

When the complete chemical composition of a medium is known (concentration)

Question 39

Complex Media

Answer 39

Contains extracts and digests of yeasts, meats, plants, etc but the medium concentration is not known.

Question 40

Types of complex media

Answer 40

Nutrient broth, tryptic soy broth, brain heart infusion

Question 41

Enriched media

Answer 41

Contains growth factors, vitamins, and other essential nutrients that organisms need to grow. They may not be able to synthesis these nutrients on their own.

Question 42

Fastidious organisms

Answer 42

Organisms that can't make certain nutrients and require them to be added to a medium.

Question 43

Non-selective medium

Answer 43

Supports the growth of all organisms

Question 44

Selective Media

Answer 44

Medium that promotes the growth of only a certain microorganism. Only supplies specific nutrients that supports the growth of that specific organism.

Question 45

Differential Media

Answer 45

Makes it easy to distinguish colonies of different bacteria by a change in the color of the colonies or the color of the medium.

Question 46

In differential media why does the color of the medium change?

Answer 46

The color changes due to the result of end products of bacterial metabolic pathways

Question 47

What is the difference between complex and chemically defined media?

Answer 47

A chemically defined medium is one in which the concentrations of every part of the medium are known. A complex medium has unknown concentrations of nutrients.

Question 48

What is the difference between selective and enriched medium?

Answer 48

A selective medium only contains the nutrients that allow a specific organism to grow. An enriched medium allows