ch 7

Question 1

1. …………. dominate the structure of most natural environments on earth
2. how do bacteria in a biofilm communicate?
3. …………. result when organisms attach to a substrate by some form of extracellular matrix that binds them together in complex organized layers
4. What comprises the human’s normal microbial flora?

Answer 1

1. biofilms
2. via quorum sensing
3. biofilms
4. symbiotic bacteria, fungi, and a few protozoa

Question 2

1. microbial associations are either ………….. or …………… .
2. How do we define symbiotic organisms?
3. How do we define non-symbiotic organisms?
4. Name and describe the 3 types of symbiotic relationships:
5. Name and describe the 2 types of nonsymbiotic relationships:

Answer 2

1. symbiotic or nonsymbiotic
2. Organisms live in close
   nutritional relationships;
   required by one or both members
3. Organisms are free-living;
   relationships not required
   for survival
4. Mutualism: obligatory. Both benefit., Commensalis: Host is neither harmed nor helped., Parasitism: parasite is dependent and hurts host.
5. Synergism: members cooperate and share nutrients. Antagonism: competition for survival

Question 3

1. What is a chemotroph?
2. what is a phototroph?
3. Most heterotrophs are …………….. .
4. What are the 2 types of chemoheterotrophs?
5. Describe a saprobe and the 2 types of saprobes:
6. Describe parasites:

Answer 3

1. gains energy from chemical compounds
2. gains energy from light through photosynthesis
3. chemoheterotrophs
4. Saprobes and parasites
5. a free-living microorganism that feeds on other organisms. Can be either opportunistic pathogens or facultative parasites
6. can be obligate or not, in either case, they derive nutrients from host

Question 4

1. What are the 2 types of transport across cell membranes and how they work:
2. Name and Describe the types of passive transport:
3. Name and Describe the types of active transport:
4. What happens during group translocation?

Answer 4

1. Passive transport - doesn’t require energy. Substances move down their concentration gradient, and active transport - requires BOTH energy and a carrier. Is independent of gradients.
2. Diffusion, Osmosis (diffusion of water), and Facilitated diffusion (involves polar and ionic molecules, and it requires carrier proteins).
3. Endocytosis (phagocytosis and pinocytosis), carrier mediated active transport, and group translocation
4. uses ATP, but conserves energy by coupling synthesis with transport. Along the route of transporting molecules, they get chemically altered into what is needed by cell.

Question 5

1. How do we define niche in a biological sense?

2. What are the 5 Environmental factors that affect the function of metabolic enzymes?

Answer 5

1. totality of adaptations organisms make to their habitat
2. Temperature
   Oxygen requirements
   pH
   Osmotic pressure
   Barometric pressure

Question 6

1. What are the 3 cardinal
   temps?
2. What are the 3 temperature adaptation Groups (philes)

Answer 6

1. Minimum temperature – lowest temperature that permits a microbe’s growth and metabolism

Maximum temperature – highest temperature that permits a microbe’s growth and metabolism

Optimum temperature – promotes the fastest rate of growth and metabolism

2. Psychrophiles: optimum temp = below 15 C

Mesophiles: optimum temp 20-40 C. Most human pathogens

Thermophiles: optimum temp >45C

Question 7

1. As oxygen is utilized it is transformed into several toxic products (4):
2. Most cells have developed enzymes that neutralize these chemicals, such as (3)
3. If a microbe is not capable of dealing with toxic oxygen, it is forced to live in oxygen free habitats, and are known as :
4. • 11. what are the 7 categories of microbes for their oxygen requirements?

Answer 7

1. Singlet oxygen (1O2), superoxide ion (O2-), peroxide (H2O2), and hydroxyl radicals (OH-)
2. Superoxide dismutase, catalase
3. obligate anaerobes
4. Aerobe – utilizes oxygen and can detoxify it
5. Obligate aerobe – cannot grow without oxygen
6. Facultative anaerobe – utilizes oxygen but can also grow in its absence
7. Microaerophilic – requires only a small amount of oxygen
8. Anaerobe – does not utilize oxygen
9. Obligate anaerobe – lacks the enzymes to detoxify oxygen so cannot survive in an oxygen environment
10. Aerotolerant anaerobes – do not utilize oxygen but can survive and grow in its presence

Question 8

1. What do you call a microbe that requires more CO2 than is present in the atmosphere?
2. Majority of microorganisms grow at a pH between ….. and …. and are called ………….
3. ………… grow at extreme acid pH
4. …………. grow at extreme alkaline pH

Answer 8

1. capnophile
2. 6 and 8 (neutrophiles)
3. Acidophiles
4. Alkalinophiles

Question 9

1. Most microbes exist under ………….. or ……….. conditions
2. ……………. require a high concentration of salt
3. ……………. do not require high concentration of solute but can tolerate it when it occurs
4. What is a barophile?

Answer 9

1. hypotonic or isotonic
2. Halophiles
3. Osmotolerant
4. can survive under extreme pressure and will rupture if exposed to normal atmospheric pressure ie: deep ocean prokaryotes

Question 10

1. Time required for a complete fission cycle is called the …………. or ………… ……… .
2. Each new fission cycle increases the population by a factor of …… – exponential growth
3. Generation times vary from ………….. to ………… .

Answer 10

1. generation, or doubling time
2. 2
3. minutes to days

Question 11

1. what is a growth curve?
2. What is the lag phase?
3. What is the exponential growth phase?
4. What is the stationary phase?
5. What is the death phase?

Answer 11

1. In laboratory studies, populations typically display a predictable pattern over time called a growth curve.
2. flat period of adjustment, enlargement; little growth
3. a period of maximum growth that will continue as long as cells have adequate nutrients and a favorable environment
4. when the rate of cell growth equals rate of cell death caused by depleted nutrients and O2, excretion of organic acids and pollutants
5. as limiting factors intensify, cells die exponentially