Chapter 6: Nutrition & Growth

Question 1

Define: photoautotroph

Answer 1

Microorganism that requires light energy and uses carbon dioxide as a carbon source

Question 2

Define: chemoautotroph

Answer 2

Microorganism that uses carbon dioxide as a carbon source and catabolizes organic molecules for energy

Question 3

Define: photoheterotroph

Answer 3

Microorganism that requires light energy and gains nutrients via catabolism of organic compounds

Question 4

Define: chemoheterotroph

Answer 4

Microorganism that uses organic compounds for both energy and carbon

Question 5

Define: obligate
aerobe

Answer 5

require oxygen for metabolism

Question 6

Define: microaerophile

Answer 6

“small amt. of oxygen liking”
Use oxygen in metabolism but not always required
Can only tolerate oxygen in amt. less than atmospheric concentration 3-10%

Question 7

Define: facultative anaerobe

Answer 7

Grow best in oxygen but can survive without oxygen

Question 8

Define: obligate anaerobe

Answer 8

“require no oxygen”
killed by oxygen

Question 9

Define: aerotolerant anaerobe

Answer 9

No aerobic metabolism but can tolerate oxygen

Question 10

Define: psychrophile

Answer 10

Optimum 10℃ (cold loving)
never cause disease in human live in snow

Question 11

Define: mesophile

Answer 11

Optimum 20℃- 40℃
many live in animals/humans=pathogens & normal flora
Think →refrigeration & cooking

Question 12

Define: thermophile

Answer 12

Optimum is 40℃-80℃ (heat loving)
live in compost pile, hot springs( water heated by earth)

Question 13

Define: hyperthermophile

Answer 13

Optimum is above 80℃
live in hot springs, mostly archaea some bacteria, membrane, nucleic acids, enzymes are unique to allow survival @ high temps.

Question 14

Define: neutrophile

Answer 14

Neutral pH (6.5-7.5)
food industry to prevent unwanted microbial growth
using microbes to kill microbes (yogurt, cheese, pickles aka fermentation)

Question 15

Define: acidophile

Answer 15

grow best in acidic environment; often times produce acid (2)
Obligate acidophiles: require acidic environment (hot springs water runoff from mines)
Acid-tolerant: can tolerate acidic environment, many used in food industry (fermentation)

Question 16

Define:
alkalinophile

Answer 16

grow best in alkaline environment; found in soil & water environment up to pH 11.5

Question 17

Define: halophile

Answer 17

grow best in hypertonic environment (up to 30% salt) will explode in freshwater
Facultative halophiles: do not require salty environment but can tolerate high salt ex: Staphylococcus auerus can survive on fresh shower skin and sweating salty skin

Question 18

Define: barophile

Answer 18

live at very high pressure @ the bottom of the ocean
require high pressure to maintain membrane & enzyme structure

Question 19

Define: biofilm

Answer 19

many species living together in a layer(surrounded by glycocalyx; slime layer/capsule) attached to a surface

Question 20

Define: quorum sensing

Answer 20

Change in physiology in response to the number of microbes present (roll call)

Question 21

Define: generation time

Answer 21

the times to completes binary fission (cell grows then divides to produce two cells)

Question 22

Describe the differences between photoautotrophs, chemoautotrophs, photoheterotrophs,
chemoheterotrophs.

o Carbon source? Energy source?

Answer 22

Photoautotroph: ENERGY from light CARBON from carbon dioxide
Chemoautotrophs: ENERGY from breaking down organic compounds CARBON from carbon dioxide
Photoheterotrophs: ENERGY from light CARBON from organic compounds other than CO2
Chemoheterotroph: Energy from breaking down organic compounds CARBON from organic compounds other than CO2
Troph- means to feed

Question 23

Describe the carbon cycle

Question 24

Describe how energy flows among organisms in an ecosystem

Question 25

Explain the importance of phototrophs and autotrophs to all life. (Hint: your answer has
nothing to do with oxygen!)

Answer 25

phototrophs get their energy from light
autotrophs can make their own organic carbon from inorganic compound
They both happen during photosynthesis (green plants, algae, cyanobacteria)

Question 26

Why can’t some organisms tolerate oxygen? (i.e. What do the aerobes have that the anaerobes do not?)

o What is it about oxygen that makes it toxic to some organisms?

Answer 26

Aerobes are able to detoxify: 1) superoxide radical: O2 (dismutase) 2) peroxide: O2- (peroxidase) 3) hydroxyl radical: OH- (catalase) 4)Singlet oxygen:1O2 (catenoid)
Organisms that survive in oxygen have enzymes or antioxidants (vitamin C & E) to destroy toxic oxygen
Since oxygen is electronegative it can take electrons from dif. part of cell and cause irreversible damage

Question 27

Nitrogen is typically the growth-limiting nutrient. (Know what this sentence means!)

o Why is this the case? (How is nitrogen usually found in the environment – is that
what organisms can use?)

o What is nitrogen fixation? What type of organism does this? (Be specific, don’t
just a say “a nitrogen fixer”!)

o Explain the importance of organisms that use nitrogen fixation to all life.

Answer 27

NO MORE NITROGEN NO MORE GROWTH
- Nitrogen in atmosphere as N2(gas). Organisms can only use NH3 (ammonia), NH4+(ammonium)
-Nitrogen Fixation N2?????
-Nitrogen Fixation essential for life on the planet, basis for crop rotation
-Rhizobium & some cyanobacteria use nitrogen fixation (??? why important to these organisms)

Question 28

Understand what “optimum growth temperature” means.

o How does temperature affect microbes?

o What temperature-related term would be used to describe a human pathogen?

Answer 28

TEMP WHICH GROW BEST: ENZYMES WORK EFFICENTLY & MEMBRANE LIPDS ARE INTACT (good barrier shape)
-Microbes are all different they grow better in dif. temp.
-Mesophiles: many live on animals/ humans = pathogens & normal flora (20℃-40℃)

Question 29

How does pH affect microbes?

o What pH-related term would be used to describe a human pathogen?

Answer 29

Changes in acidity= changes in concentration of H+ & OH- can interfere with H bonding in proteins & nucleic acids
-NuertalPhill?????? Human pathogen

Question 30

How does the concentration of a solution affect microbes? (Remember osmosis!)

o What is a halophile? Facultative halophile?

Answer 30

Osmolarity: difference in the amt. of salt you have inside the cell vs. outside of cell has an effect on osmosis which is the movement of water across the semi-permeable cell membrane
-HAROPILE: grow best in hypertonic environment (up to 30% salt) will explode in freshwater
-Facultative halophiles: do not require salty environment but can tolerate high salt
ex: Staphylococcus auerus can survive on fresh shower skin and sweating salty skin

Question 31

What is a barophile? Where might you find one?

Answer 31

Water exerts pressure in proportion to its depth (1atm of pressure for every 10 meters)
Barophile live at very high pressure
Can find at bottom of the ocean

Question 32

How do biofilms help microbes? Why are they important to people?

Answer 32

Organisms are protected from environment (Drying, antibiotics don’t’ penetrate through biofilm, UV, Chemicals) ???why impoertant to people????

Question 33

Describe the four phases of microbial growth

Answer 33

LAG Phase: no increase in cell # preparing for growth by making enzymes (to break down nutrients)
LOG Phase: exponential growth, lots of nutrients very low waste (toxic to cell) gives more dividing cells than dying/ cell wall intact(do gram stain) antibiotics that effect metabolism have more effect now
STATIONARY Phase: no increase in cell #. culture capped capacity. limiting nutrients & build up waste/ cells dividing= cells dying
DEATH Phase: out of nutrients & lots of wastes=toxic more cells dying than dividing