lecture 3 - ecology

Question 1

define ecology

Answer 1

The relationships between organisms and their physical surroundings

Question 2

biosphere

Answer 2

all living things on earth

Question 3

biome

Answer 3

larger ecosystem (ocean)

Question 4

ecosystem

Answer 4

• “A dynamic complex of plant, animal and microorganism communities and the abiotic (non-living portion) environment, interacting as a functional unit”
• Influenced by abiotic factors like temperature, nutrient availability, humidity, pressure, pH, O2 concentrations, etc.

Question 5

community

Answer 5

Interacting populations of different species
occur in same geographic location at same time

Communities form part of the larger ecosystem

ex) the microbial community on your left elbow

Question 6

population

Answer 6

a group of individuals of the same species occupying a region.
Frequently defined by geography
-Prairies vs. forests (Bison bison)
-Lung vs. gut (P. aeruginosa)

Question 7

Niche

Answer 7

1. An organism’s habitat and food requirements
   - E. coli thrives in the mammalian intestine, can eat glucose and lactose
2. An organisms’ functional role within the ecosystem
   E. coli uses O2, thus contributes to keeping the intestine anaerobic

**influenced by abiotic and biotic factors

Question 8

mutualism

Answer 8

Organisms living in a mutually beneficial relationship

ex) Human host and bacteroides in intestine

Question 9

commensalism

Answer 9

relationship benefits one organism and the other is unaffected (is any interaction ever neutral?)
ex) Human and Haemophilus influenzae in ear - usually benign –> can protect against staphococcus (mutualism) or can be parasitism too

Question 10

parasitism

Answer 10

host is harmed in some way while the parasite benefits

Question 11

what is nutrient acquisition? what type of relationship is this?

Answer 11

cows eat grass, bacteria in their stomach break down grass (cellulose) into fatty acids and protein, cow digests these NOT grass
**mutualism

Question 12

when do competitive interactions occur

Answer 12

• overlaping niches cause competition for resources (food, space, minerals)
• ability to compete influences number of organisms
• can cause exclusion of a species from an environment which can be problematic

ex) c.diff is minor member of gut community - over use of antibiotics removes competitors and it had ability to overgrow creating GI issues

Question 13

what is meant by: species within an ecosystem are interconnected and interdependent

Answer 13

Changes that influence one species can, through relationships with other species, result in changes throughout the entire community and ecosystem

Question 14

what is succession? and how does it occur

Answer 14

changes in community structure.

-caused by changes in environmental conditions (internal - seasonal,nutrients, host age, external - antibiotics)

Question 15

what are the consequences of succession?

Answer 15

• changes are unanticipated and occur at various scales

- c.diff overgrowth d/y antibiotics killing normal gut flora

Question 16

what influences chance of encountering microbes?

Answer 16

microbe distribution (where in environment)

Question 17

what influences likelihood of infection?

Answer 17

micrbe abundance (how many it takes to cause infection)
-infectious dose

Question 18

autotroph

Answer 18

Uses inorganic CO2 as its carbon source (not nutritionally dependent on other living things)
-Photosynthetic organisms like plants

Question 19

heterotroph

Answer 19

Must obtain carbon in organic form (nutritionally dependent on other living things)
Humans, E. coli

Question 20

chemotroph

Answer 20

organic molecules as energy

Question 21

phototroph

Answer 21

uses light as energy

Question 22

lithotrophs

Answer 22

uses inorganic molecules (H2S) as energy

Question 23

aerobes

Answer 23

use oxygen for metabolism, and have antioxidants

Question 24

obligate aerobes

Answer 24

require O2 (humans)

-grow at air-liquid interface

Question 25

Facultative anaerobe

Answer 25

optimal growth in O2, but can grow without O2
-E. coli, Salmonella

-grow throughout tube

Question 26

Micro-aerophile

Answer 26

grows at lower O2 concentrations

ex)Campylobacter jejuni

Question 27

anaerobes

Answer 27

don’t have metabolic enzymes for using O2

Question 28

Obligate anaerobes

Answer 28

are killed by O2

ex) Bacteroides (dominant bacteria in healthy human gut)
- grow below surface, away from O2

Question 29

Aerotolerant:

Answer 29

don’t require O2 but can survive in environments with oxygen.

-some members of Clostridium

Question 30

what factors do microbes require for growth?

Answer 30

temperature, pH, salinity

• affects where microbes can grow, can only grow optimally in a small range of conditions
• can survive small fluctuations in conditions