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Microbio Exam 2 > Lecture 5 (Factors that affect microbial growth; Microbial metabolism) > Flashcards

Lecture 5 (Factors that affect microbial growth; Microbial metabolism) Flashcards

1
Q

What are the 2 environmental factors that influence microbial survival and growth?

A

1) Temperature
2) Gas

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2
Q

Binary Fission

A

When 1 cell replicates then divide to become 2 cells

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3
Q

What are the 5 steps for bacterial growth?

A

1) Young cell is ready to go through binary fission
2) Chromosome replicated. New and old chromosomes segregate
3) Protein band (cytoskeleton proteins) forms in the center of the now enlarged cell
4) Septum forms
5) Cells divide (Sometimes they remain attached at the septum and form chains)

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4
Q

T/F: Cleavage doesn’t always occur immediately during the cell division step of binary fission

A

T

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5
Q

Temperature’s influence on microbial cell growth

A

Microbial cells assume the ambient temperature of their environments and must adapt to those temperatures

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6
Q

Microbial cells have a range of temperatures that can be displayed on a negative parabolic graph. These graphs include _______, _______, and ________ temperature points.

A

Minimum, optimal, and maximum

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7
Q

What are the independent and dependent variables on the temperature range graph for microbial cells?

A

Independent = Temperature
Dependent = Growth rate

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8
Q

What happens to a microbial cell at its optimal temperature?

A

1) Fastest growth rate (replication)
2) Optimal survival

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9
Q

What happens to a microbial cell above its maximum temperature?

A

1) The microbe’s enzymes and nucleic acids denature
2) Microbe likely to die

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10
Q

What happens to a microbial cell below its minimum temperature?

A

1) Enzyme and metabolic activities stop (become inactive)
2) Microbe does NOT necessarily die

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11
Q

T/F: Different microbial cells can grow and survive at all temperatures

A

F (all microbes have differing temperature requirements)

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12
Q

Psychhrophile microbes

A

1) Cold-loving
2) Optimum growth and survival between 0-15ºC

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13
Q

Psychotropic microbes

A

1) Cold-liking
2) Optimum growth and survival between 15-30ºC
3) Entire range = 4ºC (fridge temp) to 37ºC (mammalian temp)
4) Includes many foodborne pathogens (Listeria and S. aureus)

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14
Q

Mesophile microbes

A

1) Middle-loving
2) 20-40ºC
3) Most animal/mammalian pathogens

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15
Q

What are the 2 atmospheric gases that most influence microbial growth?

A

1) O2
2) CO2

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15
Q

Thermophile microbes

A

1) Heat-loving
2) 45-80ºC
3) Ex: microbes in hot sulfur vents, hot springs
4) NOT animal pathogens

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16
Q

T/F: Although O2 is critical for microbes that use aerobic respiration, it can exist in toxic forms inside living cells

A

T (Certain cells need the ability to detoxify O2)

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17
Q

What are the 3 categories that microbes fall into depending on their O2 use/detoxification?

A

1) Use O2 and detoxify it
2) Cannot use O2 or detoxify it
3) Do not use O2 but can detoxify it

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18
Q

How do microbes process oxygen?

A

1) Once O2 is inside the cell, it can be converted to several toxic products during metabolism and other cell processes
2) Ex: Superoxide (O2-) and hydrogen peroxide (H2O2)

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19
Q

What are 2 examples of radical toxic species that O2 is often converted to inside microbial cells?

A

1) Superoxide (O2-)
2) Hydrogen peroxide (H2O2)

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20
Q

Cells use _____ _______ to protect themselves against damage from toxic oxygen species

A

special enzymes

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21
Q

What are the names of 2 of the 2 most common special enzymes that cells use to protect themselves from toxic oxygen species?

A

1) Superoxide dismutase
2) catalase

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22
Q

What are the 2 chemical equations using superoxide dismutase and catalase to detoxify oxygen?

A

1) 2O2- + 2H+ —(superoxide dismutase)–> H2O2 + O2
2) 2H2O2 –(catalase)–> 2H2O + O2

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23
Q

Aerobe microbe

A

1) Can use oxygen for metabolism and possesses enzymes to break down toxic oxygen

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24
Q

Obligate aerobe

A

Cannot grow without oxygen

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25
Q

Facultative anaerobe

A

1) Will and can use oxygen for metabolism if it’s available, but can also grow without it
2) Many enteric microbes and bacterial pathogens (E.coli, salmonella)
3) Possess catalase and superoxide dismutase

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26
Q

Microaerophile

A

1) Doesn’t grow at normal atmospheric oxygen levels, but does require a small amount of it
2) Produces low levels of catalase, superoxide dismutase
3) Ex: deep-water microbes

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27
Q

Anaerobe

A

1) Lacks metabolic enzyme systems for using oxygen during metabolism

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28
Q

Obligate anaerobe

A

Lacks the enzymes to detoxify oxygen

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29
Q

Aerotolerant anaerobe

A

1) Has enzymes to detoxify oxygen

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30
Q

What are some common sites for anaerobic infections

A

1) Gingiva
2) Large intestine

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31
Q

Catabolism

A

1) Breaking down glucose to produce energy and yield small molecules

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32
Q

Anabolism

A

1) Building macromolecules
2) Uses energy

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33
Q

T/F: Different microbes use different catabolic processes

A

T

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34
Q

T/F: Coenzymes can act as electron carriers

A

T (most carry hydrogens that are associated with electrons)

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35
Q

What are the 3 coenzymes that act as electron carriers?

A

1) NAD
2) FAD
3) NADP

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36
Q

What is the role of NAD, FAD, and NADP (these particular coenzymes)

A

Transfer electrons during oxidation-reduction enzymatic reactions

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37
Q

T/F: Coenzymes are an enzyme

A

F (they help enzymes do their jobs)

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38
Q

ATP

A

Powerhouse molecule, high energy source

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39
Q

Where does the energy in ATP come from?

A

Phosphates (Phosphate group breaks off, releasing energy)

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40
Q

Does AMP, ADP, or ATP store the most energy?

A

ATP

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41
Q

What are the two ways that ATP can be generated?

A

1) Substrate-level phosphorylation
2) Oxidative phosphorylation

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42
Q

Substrate-level phosphorylation

A

1) A phosphate is transferred from a phosphorylated compound directly to ADP
2) An enzyme takes the phosphate away from a substrate and adds it to an ADP molecule

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43
Q

Oxidative phosphorylation

A

1) A series of redox reactions that occurs during electron transport
2) Involved NADH or FADH
3) Only occurs during 1 part of metabolism (which part?**)

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44
Q

What are the 3 main metabolic pathways?

A

1) Aerobic respiration
2) Anaerobic respiration
3) Fermentation

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45
Q

T/F: All bacteria only use 1 metabolic pathway

A

F (Some bacteria only use 1, while others use 2 or 3 pathways)

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46
Q

Aerobes

A

ONLY use aerobic respiration

47
Q

Anaerobes

A

Use anaerobic respiration OR fermentation

48
Q

Facultative Anaerobes

A

Use aerobic respiration, anaerobic, OR fermentation

49
Q

What is the ONLY difference between aerobic and anaerobic respiration?

A

The electron acceptors at the end of the ETS (O2 for aerobic, nonoxygen for anaerobic)

50
Q

What are a few of the common non-oxygen electron receptors for anaerobic respiration?

A

SO4, NO3, CO3

51
Q

What is the final electron acceptor for fermentation?

A

An organic molecule (ex: pyruvate, acetaldehyde)

52
Q

What is the 1st pathway in metabolism?

A

Glycolysis

53
Q

Where does glycolysis occur?

A

Cytoplasm in both eukaryotes and prokaryotes

54
Q

What are the two main types of glycolysis?

A

1) EMP Pathway
2) ED Pathway

55
Q

Embden-Meyerhof-Parnas (EMP) Pathway

A

1) “Classic glycolysis”
2) Used by many bacteria and eukaryotic cells

56
Q

Entner Doudoroff (ED) Pathway

A

1) Used by bacteria and archaea that lack one or more enzymes in the EMP pathway
2) These bacteria/archaea can NOT do the EMP pathway

57
Q

What is the big picture of the EMP pathway?

A

1) A 6-C glucose is converted into 2 3-C pyruvate molecules via 9 enzymatic reaction s
2) Some ATP is spent in the process
3) ATP generated via substrate-level phosphorylation
4) NADH is generated

58
Q

What are the “reactant” and “products” for the first half of the EMP pathway?

A

Reactant = glucose
Products = DHAP and G3P

59
Q

DHAP and G3P are ________ of each other, meaning they have the same chemical elements but they are arranged differently

A

isomers

60
Q

T/F: DHP is not able to enter the 2nd half of EMP, so it is first converted into a 2nd G3P molecule

A

T

61
Q

How many ATPs are used in the first half of glycolysis?

A

2 (no net gain)

62
Q

What is glucose converted to after the 1st step of the 1st half of EMP?

A

G-6-P (first phosphorylation)

63
Q

What is group translocation?

A

1) Group transport of glucose into the cytoplasm of the cell during glycolysis
2) Catalyzes 1st step of glycolysis
3) 1 ATP used

64
Q

What enzyme is used during the 1st step of glycolysis?

A

Phosphotransferase

65
Q

What happens during the 2nd half of the EMP pathway?

A

G3P is converted into pyruvate via many intermediate steps, including 2 substrate-level phosphorylation events

66
Q

What happens during substrate-level phosphorylation?

A

A phosphate is taken off a random substrate and added to ADP to form ATP

67
Q

What are the products from the 2nd half of EMP?

A

1) 2 NADH
2) 4 ATPs

68
Q

Why does everything happen twice during the 2nd half of glycolysis?

A

Because 2 G3P molecules enter the 2nd half

69
Q

What are the net yield products of the EMP pathway?

A

1) 2 ATP
2) 2 NADH
3) 2 pyruvate

70
Q

What are the products from the EMP pathway that will go on to the Krebs cycle?

A

The 2 pyruvate

71
Q

What is the 2nd glycolytic pathway?

A

Entner-Doudoroff (ED) Pathway

72
Q

What happens during the ED pathway?

A

Glucose is converted into 2 pyruvate molecules (via KDGP and G3P)

73
Q

KDPG is a molecule produced during the ED pathway. What is KDPG split into during this pathway?

A

Pyruvate and G3P (which is converted into a 2nd pyruvate molecules)

74
Q

Where do the 2 pyruvates formed during the ED pathway go next?

A

Either to the Krebs cycle or fermentation

75
Q

What are the products of the ED pathway?

A

1) 1 ATP
2) 1 NADH
3) 1 NADPH
4) 1 pyruvate

76
Q

Which pathway produces more products, the EMP or ED pathway?

A

EMP

77
Q

Where does the 1 NADH produced during the ED pathway go?

A

On to the electron transport system (ETS)

78
Q

Where does the 1 NADPH produced during the ED pathway go?

A

Biosynthesis (anabolic synthesis)

79
Q

What is the purpose of the Krebs cycle (also called the TCA cycle)?

A

1) To oxidize pyruvate
2) Electrons obtained will be used to power ATP synthesis via the ETS

80
Q

How is NADH and FADH produced during the Krebs cycle?

A

Electrons are transferred from metabolites to NAD and FAD

81
Q

Where does the Krebs cycle occur in eukaryotes?

A

Mitochondrial matrix

82
Q

Where does the Krebs cycle occur in prokaryotes?

A

Cytoplasm

83
Q

How many times does the Krebs cycle spin, and why?

A

Twice, for each pyruvate molecule that enters

84
Q

What is pyruvate converted to immediately before the Krebs cycle?

A

Acetyl CoA

85
Q

After being converted from pyruvate, what is the next molecule that acetyl CoA is converted to?

A

Citric acid (Acetyl CoA combines with OAA)

86
Q

What are the products of 1 spin of the Krebs cycle?

A

1) 4 NADH
2) 1 FADH
3) 1 ATP
4) 3 CO2
5) 1 H2O

87
Q

What are the products of the Krebs cycle per 1 glucose (1 glucose = 2 pyruvate)?

A

1) 8 NADH
2) 2 FADH
3) 2 ATP
4) 6 CO2
5) 2 H2O

88
Q

Where will the NADH and FADH formed during the Krebs cycle go on?

A

The ETS

89
Q

How is the ATP produced during the Krebs cycle?

A

Substrate-level phosphorylation

90
Q

What is the purpose of the electron transport system (ETS) and oxidative phosphorylation?

A

To use the electrons carried by NADH and FADH to generate ATP

91
Q

Where does the ETS occur in prokaryotes?

A

Inner leaflet of cytoplasmic membrane

92
Q

Where does the ETS occur in eukaryotes?

A

Inner mitochondrial membrane

93
Q

T/F: Both aerobes and anaerobes use the ETS

A

T (but there are slight differences in the pathways)

94
Q

What is the enzyme complex used during the ETS and oxidative phosphorylation?

A

NADH dehydrogenase enzyme complex

95
Q

What happens during part 1 of the ETS?

A

1) Electrons are brought in from the NADH produced in the Krebs cycle via the NADH dehydrogenase complex
2) Electrons are passed on to the chain of electron carriers

96
Q

What happens during the 2nd part of the ETS?

A

1) Each adjacent pair of electron carriers undergoes a redox reaction as e- are passed from one protein carrier to the next
2) The last electron carrier (cytochrome oxidase) passes the e- to the terminal acceptor O2
3) As e- carries shuttle e-, they transport H+ into the periplasm (creating a H+ gradient, aka proton motive force)

97
Q

What does the H+ gradient create across the cell membrane

A

Electrochemical gradient

98
Q

What happens during part 3 of the ETS?

A

1) H+ crosses the membrane at the ATP synthase complex
2) As H+ flows through the ATP synthase complex F0 subunit, the F1 subunit rotates and pulls ADP and P in
3) This rotation drives the formation of ATP
4) ATP is released back into the cytoplasm

99
Q

What is the name of the last electron carrier?

A

Cytochrome oxidase

100
Q

What process occurs at the ATP synthase enzyme complex to produce ATP?

A

Oxidative phosphorylation (ADP -> ATP)

101
Q

What is the potential ATP yield of products for the aerobic ETS?

A

34 ATPs (30 from NADH and 4 from FADH)

102
Q

What is the maximum energy yield from aerobic respiration, including glycolysis, the Krebs cycle, and ETS?

A

36-38 ATP

103
Q

How many ATPs are usually produced during each process from 1 glucose: Glycolysis, Krebs cycle, ETC

A

Glycolysis = 2 ATPs
Krebs = ~2 ATPs
ETC = 34 ATPs

104
Q

What type of phosphorylation do glycolysis and the Krebs cycle use?

A

Substrate-level phosphorylation

105
Q

What type of phosphorylation does the ETS use?

A

Oxidative phosphorylation

106
Q

T/F: Some aerobic organisms don’t generate the maximum amount of ATP (38)

A

T (some prokaryotes and some eukaryotes)

107
Q

Why are some prokaryotes not able to generate the maximum amount of ATP?

A

1) All bacteria vary widely in the # of cytochromes they have
2) Some bacteria lack cytochrome c oxidase and use a different enzyme that is less efficient

108
Q

Why are some eukaryotes not able to generate the maximum amount of ATP?

A

Movement of NADH (from glycolysis) from the cytoplasm into the mitochondrial matrix requires some energy

109
Q

What is the one carrier molecule in the ETC that can bypass the next carrier in the chain and transfer electrons directly to oxygen?

A

Flavoprotein

110
Q

What 2 highly potent cellular toxins does flavoprotein sometimes produce in the ETS?

A

1) Hydrogen peroxide
2) Superoxide

111
Q

What 2 enzymes do bacteria that use aerobic respiration produce to break down the flavoprotein toxins?

A

1) Catalase
2) Superoxide dismutase

112
Q

T/F: The terminal enzyme in ETS during anaerobic respiration is cytochrome oxidase, just like during aerobic respiration

A

F (it is something different, sometimes nitrate reductase)

113
Q

T/F: The NADH and FADH for aerobic and anaerobic respiration generate the same amount of ATP

A

F (NADH and FADH in anaerobic respiration produce much less ATP, the numbers will vary by microbe)

114
Q

What is the possible range for total anaerobic ATP yield?

A

2-36 ATPs

115
Q

Where do all of the metabolic pathways occur for prokaryotes?

A

All in the cytoplasm (ETS is in the cytoplasmic membrane)

116
Q

Where do all of the metabolic pathways occur for eukaryotes?

A

Glycolysis = cytoplasm
Krebs cycle = Mitochondrial matrix
ETS = Inner mitochondrial membrane

Microbio Exam 2 (5 decks)

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