Chp. 6 & Chp. 5 selected pages

Question 1

Microbial Growth

• Physical
• Chemical

Answer 1

Physical- temperature, pH, osmotic pressure

Chemical- sources of C, N, S, P, O, trace elements, and organic growth factors

Question 2

Minimum growth temp

Answer 2

lowest temp at which the species will grow

Question 3

Optimum growth temp

Answer 3

temp at which the species grows best

Question 4

maximum growth temp

Answer 4

highest temp at which growth is possible

Question 5

Psychrophile

Answer 5

-likes 0 to 20 deg C, 15 deg C is optimum
-oceans and polar regions
unlikely to spoil food

e.g.snow algae

Question 6

Psychotroph

Answer 6

• likes 0-30 deg C, but 20-30 deg C is optimum
• can grow at lower temps
• food spoilage

e.g. molds

Question 7

Mesophiles

Answer 7

• likes 20-40 deg C
• optimum is 37 deg C
• likes human body temp
• lives in terrestrial and aquatic areas
• on plants and animals
• may cause spoilage

e.g. many bacteria that cause disease are mesophiles

Question 8

Theromphile

Answer 8

• likes 40-80 deg C, optimum 50-60 deg C
  e. g. runoff from hot springs
  e. g. Thermus aquaticus in runnoff from hot springs in Yellowstone

Question 9

Hyperthermophile

Answer 9

• optimum 80 deg C
• many in Archae domain
• inside middle of hot springs
• deep see hydrothermal vents (volcanoes under ocean)

e.g. Sulfolobus, an archaen, lives in YS

Question 10

pH

Answer 10

A. happiest at neutral
B. acidophile- acids
e.g. molds pH 5, archeans at very low pH in Yellowstone
e.g. Lactobacillus- bacteria in yogurt, lower pH, produces some acids
C. alkaliphile- likes basic environment

To neutralize acids and maintain pH, chemical buffers are included in the growth medium.

Question 11

Salinity

Answer 11

a. Halophile- likes salty environment, organisms in Mono Lake, Great Salt lake

Question 12

Osmotic pressure

Answer 12

if in a solution whose concentration of solutes is higher than in cell (environment is hypertonic to the cell), the cellular water passes out through the plasma membrane to the high solute concentration.

Question 13

Carbon source

Answer 13

1. autotroph- uses inorganic source of carbon
2. heterotroph- uses organic source of carbon

Chemohetertrophs- get most of their carbon from the source of their energy–organic materials such as proteins, carbohydrates, and lipids.
-Chemoautotrophs and Photoautotrophs derive their carbon from CO2

Question 14

obligate anaerobe/strict anaerobe-

Answer 14

requires absence of O2 for microbe to survive

Question 15

microaerophilic

Answer 15

uses small amounts of O2

Question 16

Oxygen gas and metabolism

Answer 16

• oxygen gas is used by organisms in reactions that yield energy
• oxygen gas can be toxic- various forms of O2 can kill cells
• organisms that use O2 must deal with these toxic forms

Question 17

obligate anaerobe/strict anaerobe

Answer 17

requires absence of O2 for microbe to survive

Question 18

aerotolerant

Answer 18

tolerates O2

Question 19

Biofilms

Answer 19

community of organisms made possible by slime layer (eps)

Question 20

Extracellular polymeric substance (EPS)

Answer 20

new name for the glycocalyx that helps bacteria attach to surfaces, the old name was slime layer

Question 21

Biofilms

Answer 21

formed against a surface, such as a rock in a pond, a human tooth, or a mucous membrane

e.g. Streptococcus mutans has a slime layer, causes cavities

Question 22

Advantages of living in a biofilm

Answer 22

1. prevents dehydration
2. share nutrients
3. protection from host immune system
   
   • antibodies (proteins produced by host that fight infection)
   • phagocytosis by WBC
4. protection from antibiotics used in the treatment of disease

Question 23

Biofilms and Human health

Answer 23

• biofilms form on almost all medical devices
• encountered in many disease conditions, such as infections related to the use of contact lenses, dental caries, and infections by pseudomonad bacteria.

Question 24

Bacterial method of reproduction

Answer 24

Bacteria normally reproduce by Binary Fission

1. cell elongates and DNA is replicated
2. CW and PM begin to restrict
3. Cross-wall forms, complete separating the two DNA copies
4. Cells separate

Question 25

a. direct microscopic count

b. indirect count

Answer 25

a. get an exact cell number

b. not necessary to count microbial cells to estimate numbers

Question 26

standard plate count

Answer 26

a. serial dilutions- dilutions to do in a row
b. grow bacteria on media in petri plates- 1 ml in plates
c. count colonies and calculate cfu/ml

Question 27

turbidity

Answer 27

a. use spectrophotometer
b. measure light absorbance of test tube with bacteria
c. measurements are in O.D. (optical density)
- can correlate with standard plate count

Question 28

Dry weight

Answer 28

a. bacteria removed from growth medium
b. filter to remove extraneous material
c. dried in desiccator

Question 29

Growth curve

Answer 29

• lag phase
• exponential phase
• stationary phase
• death phase

Question 30

lag phase

Answer 30

organisms get used to the medium

Question 31

exponential phase

Answer 31

optimal growth, rapid cell division

Question 32

stationary phase

Answer 32

nutrients start to run out, some cells die, some still growing, stagnant

Question 33

death phase

Answer 33

cell death

Question 34

Generation time/doubling time

Answer 34

time it takes for 1 cell to divide into 2

Question 35

N= N0 2^n

Answer 35

N0= number of cells at the beginning
N is total number at the end
n is number of generations

Question 36

Nitrogen cycle

Answer 36

nitrogen in the atmosphere goes through fixation, nitrification, and denitrification. Nitrates assimilated into plants and animals after nitrification go through decomposition, ammonification, and then nitrification again.

Question 37

Ammonification

Answer 37

release of ammonia

Question 38

Nitrogen Nitrification

Answer 38

The next sequence of reactions in the nitrogen cycle involves
the oxidation of the nitrogen in the ammonium ion to produce
nitrate

Question 39

Nitrogen Denitrification

Answer 39

can lead to a loss of nitrogen

to the atmosphere, especially as nitrogen gas

Question 40

Nitrogen fixation

Answer 40

bacteria, such as cyanobacteria, directly uses as a nitrogen source and convert nitrogen gas to ammonia

Question 41

Nitrogen-fixing bacteria

Answer 41

Rhizosphere
Azotobacter
Clostridium

Question 42

Photosynthesis

Answer 42

first step of carbon cycle in which photoautotrophs such as cyanobactera, green plants, algae, FIX carbon dioxide into organic matter using energy from sunlight

Question 43

Carbon cycle second step

Answer 43

chemoheterotrophs such as animals and protozoa, eat autotrophs and in turn be eaten by other animals

• thus, organic compounds of the autotrophs are digested and resynthesized, the carbon atoms of CO2 are transferred from organism to organism up the food chain
• when chemoheterotrophs satisfy energy requirements, energy released through respiration, CO2 immediately becomes available to restart cycle.

Question 44

Decomposer

Answer 44

When plants and animals die, organic compounds are decomposed by bacteria and fungi