BIS 2A Lecture Notes - Lecture 11: Electron Acceptor, Pyruvate Dehydrogenase, Citric Acid Cycle

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5 May 2018

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Oxidation of Pyruvate and the TCA Cycle

●involves NAD+ and coenzyme A (CoA)

●oxidizes pyruvate and lead to a loss of one carbon via decarboxylation

●creates a new molecule called acetyl-CoA

○involved in the Krebs Cycle or Tricarboxylic Acid (TCA) cycle

Different Fates of Pyruvate and Other End Products of Glycolysis

●end products:

○2 pyruvate molecules

○ 2 ATPs

○2 NADH molecules

●Fates of ATP and NADH

○ATP

■used for other cellular functions (biosynthesis, transport, replication,

etc)

○NADH

■Fermentation: cell recycles NADH back to NAD+

ーelectrons initially taken from the glucose derivatives are

returned to more downstream products via red/ox transfer

ーNADH donate electrons to the electron transport chain

●Fate of Cellular Pyruvate

○used as terminal electron acceptor in fermentation

○secreted as waste

○further oxidized for free energy

○intermediate compound

The Further Oxidation of Pyruvate

●Conversion of Pyruvate into Acetyl-CoA

○catalyzed by enzyme pyruvate dehydrogenase

○pyruvate is oxidized by NAD+, decarboxylated, and covalently linked to a

molecule of coenzyme A via a thioester bond

○results in a loss of mass from the cell as CO2 diffuses or is transported out of

the cell as a waste product

○one molecule of NAD+ is reduced to NADH during this process per molecule

of pyruvate oxidized

○end products: CO2 as waste + one molecule of NADH

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Document Summary

Oxidizes pyruvate and lead to a loss of one carbon via decarboxylation. Involved in the krebs cycle or tricarboxylic acid (tca) cycle. Different fates of pyruvate and other end products of glycolysis. Used for other cellular functions (biosynthesis, transport, replication, etc) Fermentation: cell recycles nadh back to nad+ Electrons initially taken from the glucose derivatives are returned to more downstream products via red/ox transfer or. Nadh donate electrons to the electron transport chain. Used as terminal electron acceptor in fermentation. Pyruvate is oxidized by nad+, decarboxylated, and covalently linked to a molecule of coenzyme a via a thioester bond. Results in a loss of mass from the cell as co2 diffuses or is transported out of the cell as a waste product. One molecule of nad+ is reduced to nadh during this process per molecule of pyruvate oxidized. End products: co2 as waste + one molecule of nadh. Bacteria and archaea: occurs in cytosol eukaryotes: occurs in mitochondria.

Related Questions

(31. What is the purpose of cellular respiration/

a. To get O2 into our bodies and to get CO2 out of our bodies

b. To use the energy of sunlight to synthesize sugars

c. To make ATP to power cellular activities d. To hydrolyze ATP

(36. Which of the following accurately describes a distinction between lactic acid fermentation and alcoholic (ethanol) fermentation?

a. Lactic acid fermentation occurs in prokaryotes, whereas alcoholic (ethanol) fermentation occurs in eukaryotes

b. The final electron acceptor in lactic acid fermentation is pyruvate; the final electron acceptor in alcoholic (ethanol) fermentation is acetaldehyde

c. In lactic acid fermentation, NADH is produced by glycolysis; in alcoholic (ethanol) fermentation, NADH is produced by the Krebs cycle

d. In lactic acid fermentation, cell use CO2 in place of oxygen; in alcoholic (ethanol) fermentation, cells use SO4

(37. Which pathway is see in both fermentation and aerobic respiration?

a. Krebs cycle

b. Electron transport

c. Glycolysis d. Pyruvate oxidation

(50. How many molecules of carbon dioxide (CO2) would be produced with 5 turns of the cirtic acid cycle?

a. 2

b. 5

c. 10

d. 12

e. 60

lilaccrocodile636

1. Plants need which of the following to carry on photosynthesis?

a. H2O

b. CO2

c. O2

d. both O2 and CO2

e. both H2O and CO2

2. Organisms that derive their chemical energy either from the process of chemosynthesis or photosynthesis are classified as

a. autotrophs.

b. parasites.

c. heterotrophs.

d. saprophytes.

e. mutualists.

3. The carbon source for organisms that derive their energy from photosynthesis is

a. carbon monoxide.

b. carbon dioxide.

c. hydrocarbons.

d. methane.

e. glucose.

4. The oxygen released in photosynthesis comes from

a. carbon dioxide.

b. glucose.

c. ribulose bisphosphate.

d. water.

5. When chlorophyll a molecules absorb energy, the molecules

a. release electrons.

b. release X-rays.

c. release energy.

d. release electrons and X-rays.

e. release electrons and energy.

6. The flow of what particle across the thylakoid membrane powers the production of ATP?

a. electrons

b. hydrogen ions

c. oxygen

d. carbon dioxide

e. phosphate ions 2

7. The light-independent reactions were discovered by

a. M. D. Hatch.

b. Andrew Benson.

c. Melvin Calvin.

d. Robert Hill.

e. both Andrew Benson and Melvin Calvin.

8. For each six atoms of carbon dioxide fixed in the light-independent reactions, how many molecules of PGAL (phosphoglyceraldehyde) are produced?

a. 2

b. 3

c. 6

d. 12

e. 15

Chapter 7

9. The ultimate source of energy for living things is

a. the Krebs cycle.

b. fossil fuels.

c. the sun.

d. glycolysis.

e. aerobic respiration.

10. When molecules are broken apart in respiration

a. the heat produced is used to drive biological reactions.

b. the oxygen in the compounds that are broken apart is used as an energy source.

c. the energy released in respiration is channeled into molecules of ATP.

d. ATP is converted into ADP.

e. ADP is released as a waste product.

11. ATP

a. can be produced by photosynthesis.

b. is produced in the degradation of organic compounds such as glucose.

c. is generated in anaerobic respiration.

d. is released in aerobic respiration.

e. all of these

12. Which part of the energy-releasing pathway can convert all carbon that enters to carbon dioxide?

a. fermentation

b. glycolysis

c. Krebs cycle

d. electron transport

e. phosphorylation

13. Which liberates the most energy in the form of ATP?

a. aerobic respiration

b. anaerobic respiration

c. alcoholic fermentation

d. lactate fermentation

e. All liberate the same amount, but through different means.

14. Aerobes use ________ as the final electron acceptor in electron transport phosphorylation.

a. hydrogen

b. carbon

c. oxygen

d. H2O 3

15. Glycolysis depends on a continuous supply of

a. NADP.

b. pyruvate.

c. NAD+.

d. NADH.

e. H2O.

16. Glycolysis

a. occurs in the mitochondria.

b. results in the production of pyruvate.

c. occurs in the cytoplasm.

d. occurs in the mitochondria and results in the production of pyruvate.

e. results in the production of pyruvate and occurs in the cytoplasm.

17. The end product(s) of glycolysis is(are)

a. acetyl CoA.

b. carbon dioxide.

c. pyruvate.

d. glucose.

e. glucose and carbon dioxide.

18. Which is capable of being reduced during both glycolysis and the Krebs cycle?

a. NAD+

b. FAD+

c. ADP

d. NADH

e. NADP+

19. The Krebs cycle takes place in the

a. ribosomes.

b. cytoplasm.

c. nucleus.

d. mitochondria.

e. chloroplasts.

20. The breakdown of pyruvate in the Krebs cycle results in the release of

a. energy.

b. carbon dioxide.

c. oxygen.

d. energy and oxygen.

e. energy and carbon dioxide.

ochremole959

Which of the following is common to both aerobic and anaerobicmicrobes?

	Fermentation
	An electron transport chain
	Pyruvate oxidation
	Glycolysis
	All of the above

The primary purpose of catabolism is

	generation of ADP.
	generation of ATP.
	oxidation of NADH to NAD⁺.
	degradation of organic molecules.
	biosynthesis.

What is a fate of pyruvate during alcoholic fermentation byyeast?

	It is reduced to lactic acid.
	It is oxidized to form glucose and carbon dioxide
	It is cleaved to form acetylaldehyde and carbon dioxide.
	It is catabolized in glycolysis.
	It is oxidized to form lactic acid and carbon dioxide.

Electrons needed to reduce an oxidized electron acceptor areprovided by

	a) externally provided compounds such asH<sub>2</sub>, lactate or formate.
	b) an intermediate electron carrier such as NADH.
	c) 0<sub>2</sub>.
	d) Both a and b
	e) All of the above

How are aerobic respiration and anaerobic respirationsimilar?

	Both use oxygen as a terminal electron carrier.
	These are other names for glycolysis.
	Both utilize inorganic molecules as terminal electronacceptors.
	Neither receives electrons from glycolysis.
	Anaerobic respiration does not exist in microbes.

The conversion of phosphoenolpyruvic acid (PEP) topyruvate

	a) releases CO<sub>2</sub>.
	b) involves the conversion of ADP and ATP.
	c) involves substrate-level phosphorylation.
	d) Both a and b
	e) Both b and c

Which of the following is the best definition offermentation?

	The reduction of glucose to pyruvic acid
	The complete catabolism of glucose to CO₂ andH₂O
	The oxidation of a carbohydrate with organic molecules servingas electron donors and acceptors
	The production of ATP from glucose
	The production of ethanol from glucose

A reaction that yields energy has a

	positive ?G_o?.
	negative ?G_o?.
	positive ?E_o?.
	negative ?E_o?.
	negative ?H_o?.

Oxidation and reduction reactions are always coupledbecause

	a) electrons generally accompany protons.
	b) protons generally accompany protons.
	c) electrons cannot exist free in solution.
	d) Both a and b
	e) All of the above

10.

Which of the following is true of aerobic respiration?

	It involves the reduction of oxygen.
	It involves the oxidation of oxygen.
	It involves the reduction of lactic acid.
	It involves the oxidation of lactic acid.
	It does not generate ATP.

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BIS 2A Lecture Notes - Lecture 11: Electron Acceptor, Pyruvate Dehydrogenase, Citric Acid Cycle

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