Lecture 2 Notes (Part 3)

Question 1

Primer

Answer 1

Is a short strand of RNA or DNA that serves as a starting point for DNA synthesis

Question 2

What is required for DNA replication and why?

Answer 2

1. Primer
2. Because the enzymes that catalyze this process (DNA polymerase) can only add new nucleotides to an existing strand of DNA

Question 3

How many nucleotides typically make up a primer?

Answer 3

20

Question 4

What is a major advantage for quantitative PCR and molecular probing? (2)

Answer 4

1. Can be very specific

2. Does not require growth

Question 5

What is a community?

- Whittaker, 1975

Answer 5

A system of organisms living together and linked together by their effects on one another and their responses to the environment they share

Question 6

What is a community?

- Ricklefs and Miller, 2000

Answer 6

The many population of the many different organisms that we see in a particular place and that are tied to one another by feeding relationships

Question 7

Neutralism

Answer 7

Lack of interaction between 2 populations

Question 8

When is neutralism more likely to occur? (2)

Answer 8

1. Between populations with extremely different metabolic capabilities
2. Populations that are spatially distinct from each other

Question 9

Commensalism

Answer 9

An association between two organisms in which one benefits and the other derives neither benefit nor harm

Question 10

Synergism

Answer 10

2 populations are both benefiting from the relationship but when the relationship is NOT obligatory

Question 11

What do methanogens produce? How?

Answer 11

Methane from fermentation of acetate or reduction of CO2 with H2 from the oxidation of propionate or butyrate and caproate

Question 12

What do methanogens provide? What does it allow?

Answer 12

1. H2 sinks for syntrophic bacteria
2. Allows for counting of growth
   - if too much H2 it will shut down

Question 13

Mutualism (symbiosis)

Answer 13

Obligatory relationship between 2 populations that benefits both populations

Question 14

What are 2 examples of mutualism?

Answer 14

1. Lichens with a fungus

2. Mycobiont provides support and nutrient transport to phycobiont

Question 15

Competition

Answer 15

A negative relationship between 2 populations in which both populations are adversely affected with respect to their survival and growth

Question 16

When does competition occur?

Answer 16

When 2 populations use the same resources, which limits nutrients and space

Question 17

Competitive exclusion principle

Answer 17

2 populations cant occupy exactly the same niche or use the same resources

Question 18

What is the typical result of competition?

Answer 18

1 population will win the competition and the other will be eliminated

Question 19

How can a population avoid direct competition?

Answer 19

By using different resources at different times

Question 20

How can competition be assessed?

Answer 20

Experimentally between pure cultures

Question 21

Amensalism

Answer 21

Microorganisms that produce substances toxic to competing population will naturally have a competitive advantage

Question 22

What are 2 other names for amensalism?

Answer 22

1. Allelopathy

2. Antibiosis

Question 23

Allelopathy

Answer 23

The chemical inhibition of one plant (or other organisms) by another, due to the release into the environment of substances acting as germination or growth inhibitors

Question 24

What 2 things are inhibitory to many bacterial populations?

Answer 24

1. Production of lactic acids

2. Low molecular weight fatty acids

Question 25

What does production of sulphuric acid by Thiobacillus thiooxidans do?

Answer 25

Lower the pH and cause acid mine drainage which prevents growth of other microorganisms

Question 26

What prevents growth of bacteria?

Answer 26

Production of antibiotics

Question 27

What is nisin produced by and what does it do?

Answer 27

1. Produced by some bacteria

2. Disrupts cell membrane properties

Question 28

Parasitism

Answer 28

The population that benefits (parasite) derives its nutritional requirement from the host, population which is harmed

Question 29

Ectoparasites

Answer 29

A parasite that lives outside the cells of the host population

Question 30

What is an example of an ectoparasite?

Answer 30

A flea

Question 31

Endoparasites

Answer 31

A parasite that lives inside the host cell

Question 32

What us an example of an endoparasite?

Answer 32

A tapeworm

Question 33

What are viruses of bacteria called?

Answer 33

Bacteriophages

Question 34

How do viruses form parasites? (4)

Answer 34

1. Viruses dock at the bacterial cell surface
2. Injects its DNA (which is first replicated)
3. Proteins are synthesized
4. Precipitate around the viruses genome to form parasites

Question 35

When does predation occur?

Answer 35

When one organism, the predator, engulfs and digests another organism, the prey

Question 36

Selection

Answer 36

Microorganisms must extract energy efficiently and matter from the environment in order to grow and transfer genetic material to offspring

Question 37

R-strategist

Answer 37

Success may be related to better molecule machinery for macromolecule synthesis

Question 38

K-strategist

Answer 38

Success may be related to a better use or a more efficient extraction of the energy and matter in the immediate environment

Question 39

What happens to the population when the density is low?

Answer 39

The rate of population changes and is dominated by r

Question 40

What happens to the population when the density is high?

Answer 40

The growth rate is dominated by k