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Microbiology > Chapter 4 > Flashcards

Chapter 4 Flashcards

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Biology 101 flashcards
1
Q

Reduction potentials

A

The reduced substance with the more negative reduction potential donates electrons.
Ex. H donates electrons

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2
Q

The electron tower

A

Biological systems use electron flow to obtain energy.

Diagrams reduction potentials for biological molecules.

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3
Q

Difference in potential between donors and acceptors expressed as deltaE

A

Longer the drop of e from donor to recipient, more energy and larger the deltaE.

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4
Q

NAD as a redox e carrier

A

Redox runs usually involve reactions between intermediates.

e carriers are divided into two classes.

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5
Q

NAD/NADH cycling

A

Coenzymes make it possible for chemically dissimilar molecules to interact as primary e-donor and terminal e-acceptor.
-coenzyme acts as intermediary.

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6
Q

High energy compounds and energy storage

A

Redox runs release energy, cell stores it for functioning.

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7
Q

Energy rich compounds and energy storage II

A

Long term energy storage involves insoluble polymers that can be oxidized to generate ATP.

  • Ex. in prokaryotes: glucose and S
  • Ex. in eukaryotes: starch
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8
Q

Energy conservation

A

Two rxn series linked to energy conservation in chemoautotrophs: fermentation and respiration.
Differ in mechanism of ATP synthesis
-Fermentation: substrate level phosphorylation
-Respiration: oxidative phosphorylation.

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9
Q

3 methods of ATP synthesis

A

Fermentation
Respiration
Photophosphorylation

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10
Q

Terminal e acceptors

A

Ultimate destination of e is terminal electron acceptor of process.
Type of terminal e acceptor

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11
Q

Terminal e acceptor II

A

Respiration:externally supplied e acceptor
Fermentation: terminal e acceptor not supplied from the environment.
–Fermentation

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12
Q

Glycolysis

A

A sequence of enzyme catalyzed runs by which glucose is conveyed into pyruvate.

  • Pyruvate can be oxidized further.
  • Pyruvate can also be used as a precursor to biosynthesis.
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13
Q

Key facts about glycolysis

A

Occurs in cytoplasm.
Used by most autotrophs and heterotrophs and both aerobes and anaerobes.
Breaks down glucose.
O2 not required.

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14
Q

Glycolysis II

A

Two stages:

-Stage 1 catalyzes the splitting of glucose (predatory).

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15
Q

Glycolysis III

A

Stage 2: catalyzes the oxidation of glyceraldehyde-3-phosphate to pyruvate (payoff phase).
-consists of 5 rxns
-generates 4 ATP’s, net gain of 2 ATP
Generates NADH

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16
Q

Stage 1 summary

A

Not redox and does not release energy.
2 ATP’s are used to convert glucose to fructose 1,6-biphosphate.
Aldolase splits ructose 1,6-biphosphate

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17
Q

Stage 2 summary

A

This is when the first redox run occurs.

Each glyceraldehyde 3-phosphate gets another phosphate.

18
Q

Glycolysis summary

A

ATP needed
-2 ATP molecules are used to phosphorylate glucose.
ATP produced
-

19
Q

Fermentation

A

ATP is produced by a mechanism called substrate level phosphorylation.
The fermentable substrate is both an e donor and e acceptor.
Not all compounds can be fermented.

20
Q

Regeneration of NAD+

A 
Reduced coenzyme (NADH) produced in stages I and II. 
-Limited amount of NAD+, for glycolysis to continue NAD+ must be regenerated, fermentation
REGENRATES NAD+ FOR REUSE.
21
Q

Glucose fermentation: Net and practical results

A 
Results of glucose fermentation. 
-glucose is broken down
-fermentation products are produced
-Net 2 ATP's
Fermentation products may be used for
-food production
-industrial application
Energy yields from fermentation are low
-Carbon atoms are only partially oxidized
-difference in reduction potentials is small between primary e donor and terminal e acceptor.
22
Q

Fermentation

A

Yeast fermentation produces alcohol and CO2 instead of lactic acid.

23
Q

Alcohol fermentation

A

CO2 is released from pyruvic acid to form intermediary acetaldehyde.
Acetaldehyde is reduced to ethanol by e from NADH.

24
Q

Pyruvate end points

A

Pyruvate produced from carbohydrate metabolic pathways is metabolized in various ways.

  • precursor in biosynthetic reactions
  • oxidized to CO2
25
Q

Respiration I

A

Respirators obtain some energy from glycolysis
Two kinds:
-Aerobic
-Anaerobic

26
Q

Aerobic respiration

A 
Aerobes undergo aerobic respiration
-Kreb's cycle
-oxidative phosphorylation
Oxidation using O2 as a terminal e acceptor
Higher ATP yield than fermentation
27
Q

Significance of energy transfer

A

In glycolysis and fermentation, net production of 2 ATP.

Glycolysis+aerobic respiration=38 glucose per glucose.

28
Q

oxidative decarboxylation of pyruvate

A

Pyruvic acid from glycolysis can enter cycle but must be converted to acetyl CoA.
-Removes one molecule of CO2
-Transfer of e and NAD
-Addition of coenzyme A
Pyruvate is oxidized to acetyl CoA, CO2 and NADH by pyruvate dehydrogenase.
Acetyl CoA oxidized to CO2 in Kreb’s cycle.

29
Q

Citric Acid Cycle I

A 
Starts w/ acetyl CoA.
Acetyl groups are converted to CO2
H's removed and e transferred to coenzymes that serve as e carriers. 
Significant events of cycle
-oxidation of carbon
-removal of e to coenzyme
-substarte level energy capture
30
Q

Citric Acid Cycle II

A

Pathway through which pyruvate is completely oxidized to CO2.

  • Initial steps same as glycolysis
  • Per glucose molecule, 6 CO2 released and 38 ATP generated.
  • catabolism and biosynthesis
31
Q

The gist of CAC

A

Pyruvate is split into 3 CO2
The e produced in the process are put on e carriers.
e are taken to e transport system.

32
Q

Biosynthesis and CAC

A

A

33
Q

Electron transport and oxidative phosphorylation

A

Series of redox rxn’s to generate a H+ gradient

34
Q

Electron transport systems

A

Membrane associated.
Mediate transfer of e from primary donor to terminal acceptor.
Conserve some energy released during transfer and use it to synthesize ATP.

35
Q

Some e carriers

A

NADH dehydrogenases:

Flavoproteins:

36
Q

Cytochromes

A

Carriers that contain heme prosthetic groups.

Accept and donate single electron via iron atom.

37
Q

Iron sulfur proteins

A

Contains clusters

38
Q

Organization of e carriers in bacteria

A

Organized into dehydrogenase and oxidase complexes connected by quinones.
Quinones accept e from dehydrogenases.

39
Q

Generation of proton motive force

A

e transport system oriented in cytoplasmic membrane so that as e are transported, protons are separated.
Carriers in ETC are arranged in increasingly positive reduction potential.
Final carrier in chain donates e and protons to terminal e acceptor.

40
Q

The proton motive force

A

During e transfer, several

41
Q

Proton motive force and ATP synthesis

A

ATP synthase complex that converts proton motive force into ATP.
Two components:
-

Microbiology (39 decks)

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