Ecology and Environmental Microbiology

Question 1

Microbes are integral to ___ cycles that shape the environment of the earth and its oceans.

Answer 1

Biogeochemical

Question 2

Biogeochemical cycling involves what type of reactions? These reactions change ____ and _____ characteristics of nutrients.

Answer 2

Redox

Chemical, physical

Question 3

Redox reactions in biogeochemical cycling involves ____ electrons from one compound and ____ them to another

Answer 3

Removing

Attaching

Question 4

Function of greenhouse gases

Answer 4

Trap heat in the atmosphere that is reflected from earth’s surface, rather than allowing it to radiate into space

Question 5

When do greenhouse gases accumulate?

Answer 5

If the rate upon which they enter the atmosphere exceeds the rate that the natural carbon and nitrogen cycles can replace them

Question 6

3 greenhouse gases

Answer 6

Carbon dioxide (CO2)
Methane (CH4)
Nitrous oxide (N2O)

Question 7

Which greenhouse gas is the most abundant?

Answer 7

CO2

Question 8

Which greenhouse gas has 25 times the global warming potential of CO2?

Answer 8

Methane

Question 9

Microbial sources of CO2 (2)

Answer 9

Respiration, fermentation

Question 10

Microbial source of methane

Answer 10

Methanogenesis

Question 11

Microbial sources of nitrous oxide (2)

Answer 11

Nitrification

Denitrification

Question 12

Carbon cycling: oxidized and reduced forms (2 each)

Answer 12

Oxidized: CO and CO2
Reduced: CH4, organic matter

Question 13

What process fixes CO2 into biomass?

Answer 13

Photosynthesis

Question 14

Microbes fix what percentage of the world’s carbon?

Answer 14

50%

Question 15

Photosynthesis produces what 2 byproducts?

Answer 15

O2

Organic compounds

Question 16

____ _____ produced by photosynthesis are oxidized back to _____ by ____ and ____.

Answer 16

Organic comounds
CO2
Respiration (glycolysis + TCA + electron transport)
Fermentation

Question 17

Carbon cycle contains what 2 sub-cycles?

Answer 17

Aerobic

Anaerobic

Question 18

Aerobic portion of carbon cycle: ____ is reduced to ____ ___ through ____ _____.

Answer 18

CO2
Organic matter
CO2 fixation

Question 19

CO2 fixation is carried out by what type of metabolizers (energy, carbon)?

Answer 19

Photoautotrophs

Chemoautotrophs

Question 20

Aerobic portion of carbon cycle: ___ ___ is oxidized to ____ through ____ and _____.

Answer 20

Organic matter
CO2
Respiration
Fermentation

Question 21

Anaerobic portion of carbon cycle: ____ is reduced to ____ by _____.

Answer 21

CO2
CH4
Methanogenesis

Question 22

Anaerobic portion of carbon cycle: ___ is oxidized to ____ by _____.

Answer 22

CH4
CO2
Methanotrophy

Question 23

What type of microbes carry out methanogenesis? What is methanogenesis?

Answer 23

Methanogens

Biological production of methane

Question 24

Microbes from what domain carry out methanogenesis? Can every type of microbe from this domain carry out this process, or only a few?

Answer 24

Archaea

Only a few

Question 25

How many tons of methane do Archaea generate per year?

Answer 25

Over 1 billion tons

Question 26

Some methanogens live in symbiosis with what 2 types of organisms?

Answer 26

Termites | Ruminants (animals with multichambered stomachs, like cows)

Question 27

Methanotrophs: some of what 2 domains of life? They use ____ as a source of ____, _____ it to _____.

Answer 27

``` Archaea, bacteria Methane Carbon Oxidizing CO2 ```

Question 28

3 stages of nitrogen cycle: forms of nitrogen and reactions creating them

Answer 28

Atmospheric nitrogen (N2) is fixed by nitrogen fixation, yielding reduced NH4 NH4 is oxidized to NO3 by nitrification (NH4 -> NO2 -> NO3) NO3 is reduced to N2 by denitrification

Question 29

What 2 organisms carry out nitrification? For the 2 organisms, what is the reaction each carries out?

Answer 29

Nitrosomonas: NH4 to NO2 Nitrobacter: NO2 to NO3

Question 30

Which organism carries out denitrification? What type of respiration is denitrification?

Answer 30

Paracoccus denitrificans | Anaerobic respiration

Question 31

What 2 organisms carry out nitrogen fixation?

Answer 31

Azotobacter | Anabaena

Question 32

What approach is taken to characterize microbial communities in humans or in nature?

Answer 32

Metagenomics

Question 33

Metagenomics involves analyzing what?

Answer 33

Genetic material derived from microbial communities

Question 34

Metagenomics can reveal _____ and ______ ______ of microbial communities.

Answer 34

Diversity | Metabolic potential

Question 35

Metagenomics: culture independent or dependent?

Answer 35

Culture independent

Question 36

Culture-dependent approach to studying microbial communities: how it works, downside

Answer 36

Microbes from different environmental and organismal sources are grown on petri dish Problem: not all microbial life is represented due to limitations of culture conditions

Question 37

Metagenomic approach to studying microbial communities: 4 steps

Answer 37

1. Isolate genomic DNA from different sources 2. PCR amplification of SSU rRNA genes 3. Clone and sequence amplified DNA 4. Compare sequences to database of known genes

Question 38

Microbiome definition

Answer 38

Collection of all microorganisms living in association with the human body

Question 39

Microbiome can also be called _____ or _____.

Answer 39

Microbiota | Microflora

Question 40

In 2007, the NIH launched the ____ _____ _____ to better understand the microbiome and its role in human health and disease.

Answer 40

Human Microbiome Project

Question 41

Studies indicate ____ - ____ different species of microbes live in the human gut, representing all ____ ____ of life

Answer 41

500-1000 | 3 domains

Question 42

Microbiome can include what non-living obligate intracellular parasites?

Answer 42

Viruses (bacteriophages, etc.)

Question 43

Microbiome in humans comes from what 3 sources?

Answer 43

Birth (interaction with birth canal and skin of caregivers) Breast milk Environment

Question 44

Human body is only what percent human cells?

Answer 44

25%

Question 45

Microbiome of gut makes what two things that humans cannot make for themselves?

Answer 45

Nutrients | Vitamins

Question 46

Gut microbiota makes _____ that affect ____ ____ and ___.

Answer 46

Neurotransmitters Brain development Behavior

Question 47

5 places where microbiome can be found on humans

Answer 47

``` Mouth Nasal passages Lungs GI tract Urogenital tract ```

Question 48

What connects the visceral organs and the brain?

Answer 48

Vagus nerve

Question 49

The vagus nerve is an important ____ pathway for the ____ _____ to influence the ____ and ____.

Answer 49

Communication Gut microbiota Brain Behavior

Question 50

Name for connection between microbiota and brain

Answer 50

Microbiota-Gut-Brain Axis

Question 51

Results of experiment with mice with intact vs. missing microbiota (2)

Answer 51

Mice with missing microbiota displayed altered behavior (stress, anxiety, depression, anti-social behavior) Anxiety phenotype could be transferred between animals through transplantation of gut microbiota

Question 52

Diseases linked to gut microbiota (8 total, 2 of immune system, 5 of brain, and one other)

Answer 52

``` Obesity Type I diabetes Inflammation Autism Major depression Alzheimers Parkinsons Multiple Sclerosis ```