Lecture 16: Aerobic Respiration

Question 1

Describe how Embden-Meyerhof Pathway, Entner-Doudoroff Pathway,Pentose Phosphate Pathway, and Citric Cycle Pathway contribute to the electron transport chain.

Answer 1

• Caused O2 as the terminal electron acceptor for the ETC
• The reduction potential from O2 to NADH is large, and makes it so you get more energy.
• The electron transport chain is the final component of aerobic respiration and is the only part of glucose metabolism that uses atmospheric oxygen. Electron transport is a series of redox reactions that resemble a relay race. Electrons are passed rapidly from one component to the next to the endpoint of the chain, where the electrons reduce molecular oxygen, producing water. This requirement for oxygen in the final stages of the chain can be seen in the overall equation for cellular respiration, which requires both glucose and oxygen.
• Oxygen is used as an electron acceptor within the electron transport chain of aerobic respiration to generate ATP. This compound is an essential component in intracellular energy transfer.

Question 2

Define the Embden-Meyerhof Pathway. (Glycolysis)

Start products? End products? Function?

Answer 2

Start Products:
Glucose + 2ADP + 2Pi + 2NAD+

End Products:
2 Pyruvate + 2 ATP + 2 NADH + H+

Function:
Provides 2 ATP and 2 NADH from 1 Glucose

Question 3

Define the Entner-Doudoroff Pathway.

Start products? End products? Function?

Answer 3

Start Products:
1 Glucose + 1ADP + 1Pi + 1NAD+ + 1NADP+

End Products:
1 Pyruvate + 1 G3P + 1ATP + 1NADH + 1NADPH

Function:
Provides 1 Pyruvate, 1 G3P, 1 ATP, 1 NADH, 1 NADPH from 1 Glucose

-Occurs in the cytoplasm

Question 4

Define the Pentose Phosphate Pathway.

Start products? End products? Function?

Answer 4

Start Products:
3 Glucose6-phosphate + 6(NADP+) + 3H2O

End Products:
2 fructose6-phosphate + 6 G3P + 3CO2 + 6NADPH + 6H+

Function:
Provides 2 NADPH for each Glucose so produces 6 NADPH

-Both anaerobic and aerobic

Question 5

Define the TCA Cycle Pathway.

Start products? End products? Function?

Answer 5

Start Products:
Pyruvate -> Acetyl CoA

End Products:
Up to 2 CO2, 3 NADH, 1 FADH2 and either 1 ATP or GTP are formed for each Acetyl CoA.

Function:
-last step

Question 6

Define substrate level phosphorylation and oxidative phosporylation for ATP synthesis, and where you find these processes in catabolism

Answer 6

SLA: direct Pi from ADP

Where its found?
-Glycolysis and citric acid cycle

Oxidative phosphorylation: Uses proton motor force

Where its found?

• ATP synthase, membrane bound
• Occurs in ETC

Question 7

Relate amounts of ATP generated to energy released from reactions in aerobic respiration

Answer 7

• Different terminal e- acceptors yield different amount amount of ATP
• Depends on the change in reduction potential

Question 8

Explain why aerobic respiration evolved in microorganisms

Answer 8

• So if you can make more ATP so now organisms that can do that have a selective advantage
• It is advantageous so you’ll see it maintain
• More energy available, so it can support larger cells and complex processes

Question 9

How much ATP is produced when NADH is the e- donor and O2 is e- acceptor?

Answer 9

O2 = 2.5 ATP/NADH

Question 10

How much ATP is produced when NADH is the e- donor and NO3- is e- acceptor?

Answer 10

NO3- = 2 ATP/NADH

Question 11

How much ATP is produced when NADH is the e- donor and S is e- acceptor?

Answer 11

S = 1 ATP/ NADH