Chapter 4

Question 1

Reduction potentials

Answer 1

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

Question 2

The electron tower

Answer 2

Biological systems use electron flow to obtain energy.

Diagrams reduction potentials for biological molecules.

Question 3

Difference in potential between donors and acceptors expressed as deltaE

Answer 3

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

Question 4

NAD as a redox e carrier

Answer 4

Redox runs usually involve reactions between intermediates.

e carriers are divided into two classes.

Question 5

NAD/NADH cycling

Answer 5

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

Question 6

High energy compounds and energy storage

Answer 6

Redox runs release energy, cell stores it for functioning.

Question 7

Energy rich compounds and energy storage II

Answer 7

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

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

Question 8

Energy conservation

Answer 8

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.

Question 9

3 methods of ATP synthesis

Answer 9

Fermentation
Respiration
Photophosphorylation

Question 10

Terminal e acceptors

Answer 10

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

Question 11

Terminal e acceptor II

Answer 11

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

Question 12

Glycolysis

Answer 12

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.

Question 13

Key facts about glycolysis

Answer 13

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

Question 14

Glycolysis II

Answer 14

Two stages:

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

Question 15

Glycolysis III

Answer 15

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

Question 16

Stage 1 summary

Answer 16

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

Question 17

Stage 2 summary

Answer 17

This is when the first redox run occurs.

Each glyceraldehyde 3-phosphate gets another phosphate.

Question 18

Glycolysis summary

Answer 18

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

Question 19

Fermentation

Answer 19

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.

Question 20

Regeneration of NAD+

Answer 20

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.

Question 21

Glucose fermentation: Net and practical results

Answer 21

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.

Question 22

Fermentation

Answer 22

Yeast fermentation produces alcohol and CO2 instead of lactic acid.

Question 23

Alcohol fermentation

Answer 23

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

Question 24

Pyruvate end points

Answer 24

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

• precursor in biosynthetic reactions
• oxidized to CO2

Question 25

Respiration I

Answer 25

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

Question 26

Aerobic respiration

Answer 26

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

Question 27

Significance of energy transfer

Answer 27

In glycolysis and fermentation, net production of 2 ATP. | Glycolysis+aerobic respiration=38 glucose per glucose.

Question 28

oxidative decarboxylation of pyruvate

Answer 28

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.

Question 29

Citric Acid Cycle I

Answer 29

``` 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 ```

Question 30

Citric Acid Cycle II

Answer 30

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

Question 31

The gist of CAC

Answer 31

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

Question 32

Biosynthesis and CAC

Answer 32

A

Question 33

Electron transport and oxidative phosphorylation

Answer 33

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

Question 34

Electron transport systems

Answer 34

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

Question 35

Some e carriers

Answer 35

NADH dehydrogenases: | Flavoproteins:

Question 36

Cytochromes

Answer 36

Carriers that contain heme prosthetic groups. | Accept and donate single electron via iron atom.

Question 37

Iron sulfur proteins

Answer 37

Contains clusters

Question 38

Organization of e carriers in bacteria

Answer 38

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

Question 39

Generation of proton motive force

Answer 39

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.

Question 40

The proton motive force

Answer 40

During e transfer, several

Question 41

Proton motive force and ATP synthesis

Answer 41

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