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Flashcards in lecture 3 - ecology Deck (30):
1

define ecology

The relationships between organisms and their physical surroundings

2

biosphere

all living things on earth

3

biome

larger ecosystem (ocean)

4

ecosystem

-“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.

5

community

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

6

population

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)

7

Niche

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

8

mutualism

Organisms living in a mutually beneficial relationship
ex) Human host and bacteroides in intestine

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commensalism

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

10

parasitism

host is harmed in some way while the parasite benefits

11

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

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

12

when do competitive interactions occur

-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

13

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

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

14

what is succession? and how does it occur

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

15

what are the consequences of succession?

-changes are unanticipated and occur at various scales
-c.diff overgrowth d/y antibiotics killing normal gut flora

16

what influences chance of encountering microbes?

microbe distribution (where in environment)

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what influences likelihood of infection?

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

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autotroph

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

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heterotroph

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

20

chemotroph

organic molecules as energy

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phototroph

uses light as energy

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lithotrophs

uses inorganic molecules (H2S) as energy

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aerobes

use oxygen for metabolism, and have antioxidants

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obligate aerobes

require O2 (humans)

-grow at air-liquid interface

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Facultative anaerobe

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

-grow throughout tube

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Micro-aerophile

grows at lower O2 concentrations
ex)Campylobacter jejuni

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anaerobes

don’t have metabolic enzymes for using O2

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Obligate anaerobes

are killed by O2

ex) Bacteroides (dominant bacteria in healthy human gut)

-grow below surface, away from O2

29

Aerotolerant:

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

-some members of Clostridium

30

what factors do microbes require for growth?

temperature, pH, salinity

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