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MicroEco > Lecture 16 - Carbon Cycling > Flashcards

Lecture 16 - Carbon Cycling Flashcards

1
Q

What are the 4 nutrient cycles microorganisms use?

A

carbon, iron, nitrogen, sulfur (CINS)

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2
Q

Which nutrient cycle is the most important for microbes?

A

nitrogen

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3
Q

What are the 3 man-made things that contribute to the carbon in the atmosphere and results in the increase of atmospheric CO2?

A

fossil fuels, deforestation, cement production

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4
Q

What is carbonated rock? What is a rule with this carbon source?

A

oceanic earth’s crust/fossil fuel source, should be inactive | should NOT be cycled, but it us used anyways

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5
Q

Which is the largest carbon reservoir in the planet?

A

carbonated rock

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6
Q

Which is the smallest carbon reservoir in the planet?

A

atmospheric CO2

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7
Q

Which carbon reservoir is the most actively cycled?

A

atmospheric CO2

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8
Q

What is due to the drastic increase in atmospheric CO2?

A

past 100 years = industrialization

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9
Q

What are the 2 carbon reservoirs in the ocean?

A

carbonate rock and dissolved/particulate organic material (DOM/POM)

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10
Q

What are the 4 carbon reservoirs on land?

A

land plants (biota), humus, fossil fuels and earth’s crust

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11
Q

How do carbon reservoirs relate to the issue of global warming?

A

CO2 and CH4 = high levels in sky = traps heat and doesn’t let it escape

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12
Q

Microorganisms may play a role in more than one nutrient cycle (ex: can fix both nitrogen and carbon). How does this overlap affect the microbe community?

A

can drive how these organisms are structured within the community

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13
Q

By how much (%) has atmospheric CO2 increased in the past century?

A

28%

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14
Q

What are autotrophs?

A

takes up CO2&raquo_space;> carbon fixation

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15
Q

What are heterotrophs?

A

takes organic carbon &raquo_space;> carbon respiration &raquo_space;> produce CO2

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16
Q

What is the primary productivity of our planet a result of? (50% what and 50% what?)

A

50-plants | 50: cyano-b, algae, microbes (CAM)

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17
Q

What cycle uses carbon anaerobically?

A

methane cycle

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18
Q

What are the 4 predominant forms of organic carbon in the environment?

A

peptidoglycan, chitin, plant polymers, insect exoskeleton

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19
Q

Why are organic polymers important?

A

help support heterotrophic activity

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20
Q

What are the 3 different components that make up a plant? (order them from which makes up most of the plant to least)

A

cellulose, hemicellulose, lignin

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21
Q

Where does the environment get peptidoglycan from?

A

bacterial cell wall

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22
Q

Where does the environment get chitin from?

A

fungal cell wall

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23
Q

What is cellulose?

A

homogenous molecule - glucose subunit repeats connected via beta-1,4-glycosidic linkage

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24
Q

How is cellulose a problem for microbes?

A

large molecule and insoluble in water

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25
Q

How do microbes get a large insoluble molecule across their cell walls?

A

secretes enzymes to break it down into smaller pieces

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26
Q

What is cellulase?

A

NOT one enzyme, CLASS of enzymes that break down cellulose

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27
Q

What are the 3 major enzymes that play a role in the breakdown of cellulose?

A

B1,4-endoglucanase, B1,4-exoglucanase, cellobiase (B1,4-glucosidase)

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28
Q

What is beta1,4-endoglucanase?

A

randomly breaks up cellulose into shorter pieces by targeting glycosidic (beta 1,4) linkage

29
Q

What is beta1,4-exoglucanase?

A

more specific = goes at end of cellulose and breaks bond at every 2 subunits == produces di-glucose

30
Q

What is beta1,4-glucosidase?

A

not all cells secrete this, cuts cellobiose into single glucose subunits

31
Q

What is cellobiose?

A

di-glucose that can be transported into cell

32
Q

What is the aerobic pathway glucose is used when it gets inside the cell?

A

TCA &raquo_space;> respiration &raquo_space;> made CO2

33
Q

What is the anaerobic pathway glucose is used when it gets inside the cell?

A

fermentation &raquo_space;> made acetate and alcohol &raquo_space;> use for energy

34
Q

What is hemicellulose? What is another name for it?

A

(xylan) heterogeneous and diverse molecule, different sugar forms, branching occurs | common in plants

35
Q

Why does it take longer and is it more difficult for organisms to break down hemicellulose?

A

branching and how super diverse it is = need a lot of enzymes because of how many different sugars there are

36
Q

What is starch?

A

glucose repeats with branching

37
Q

What are the enzymes involved in the break down of starch?

A

alpha amylase and glucoamylase

38
Q

What is a hemicellulose polymer?

A

pectin

39
Q

What does alpha amylase do?

A

attacks starch at non-reducing end = makes maltose

40
Q

What does glucoamylase do?

A

breaks alpha (1,4) and (1,6) glycosidic bonds

41
Q

What are the differences and or similarities in the structures of chitin and peptidoglycan?

A

chitin = only NAG subunits | peptidoglycan = NAG and NAM

42
Q

What molecules does N-acylglucosamine (NAG) contain?

A

carbon and nitrogen

43
Q

Why are chitin and peptidoglycan important and unique than the other organic polymers?

A

NAG serves as a source for both nitrogen cycle and or carbon cycle

44
Q

What is lignin?

A

complex and heterogeneous molecule | helps support plant’s structure/stability, protects from pathogens, encases hemicellulose

45
Q

What are the basic building blocks of lignin?

A

2 aromatic amino acids: tyrosine and phenylalanine

46
Q

What is phenylpropene?

A

what the lignin building blocks are converted into that randomly polymerize until structure is complete

47
Q

What makes lignin difficult and slow for microbes to break down?

A

complexity, diversity of molecule and aromatic rings within structure

48
Q

What is lignin peroxidase?

A

(nonspecific extracellular) peroxidase that breaks down lignin by: O2-based free radicals that react with lignin and releases the subunits | needs to be in aerobic environment

49
Q

Briefly describe how lignin is broken down in order to enter the TCA cycle. What is the end product from the TCA cycle due to lignin?

A

lignin broken down to smaller subunits = further broken down&raquo_space;> TCA&raquo_space;> made CO2 and water

50
Q

What do all enzymes used to break down the 4 organic polymers have in common?

A

all enzymes are secreted by the cell

51
Q

What is the number one most common greenhouse gas?

A

CO2

52
Q

What is the second most common greenhouse gas?

A

methane

53
Q

What is methane?

A

carbon compound5% that is 22x more effective in trapping heat

54
Q

What percent concentration of methane is it considered flammable and an explosive gas?

A

5%

55
Q

Where is a lot of methane produced and why?

A

landfills : stuff decomposes = methane released

56
Q

What percent concentration of methane can be tracked, converted, collected, and used for generating electricity?

A

35%

57
Q

What is a more common way that we deal with methane?

A

ventilate into sky

58
Q

What is the biological contributor of methane?

A

methanogenesis process

59
Q

Is the methanogenesis process aerobic or anaerobic?

A

anaerobic

60
Q

What are the 4 common places/environments is methane found?

A

wetlands, soil in anaerobic environments, landfills, guts of: cows, termites, humans

61
Q

What are methanogens?

A

strictly ARCHAEAL microbes than can produce methane

62
Q

How are methanogens autotrophic?

A

takes hydrogen and CO2 = make methane and water

63
Q

How are methanogens heterotrophic?

A

uses acetate, methanol, formate = make methane

64
Q

Are there any bacterial species known to produce methane?

A

no

65
Q

What are methanotrophs?

A

strictly bacteria that use methane as carbon source and energy via methane oxidation

66
Q

In which environment do methanotrophs live: aerobic or anaerobic?

A

aerobic ONLY

67
Q

What enzyme do methanotrophs use to oxidize methane?

A

methane monooxygenase

68
Q

What are the 3 intermediate molecules formed during methane oxidation?

A

methanol, formaldehyde, formic acid

MicroEco (10 decks)

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