Met 1: Electron Transport

Question 1

Where in the cell does the electron transport chain take place?

Answer 1

ETC is within the inner membrane of mitochondria

Question 2

1. Electrons are transferred from ____ and _____ to protein complexes within the __________
2. the energy released as the electrons move from complex to complex is harnessed to pump protons into _______________________
3. _____ is the final acceptor of electrons, and becomes _______
4. Protons flow down their concentration gradient, into the ___________
5. _________ uses this energy to create ATP

Answer 2

1. electrons are transferred from NADH and FADH2 to protein complexes within the inner mitoch membrane
2. the energy released as the electrons move from complex to complex is harnessed to pump protons into the intermembranous space
3. oxygen is the final acceptor of electrons, and becomes H20
4. Protons flow down their concentration gradient, into the mitochondrial matrix
5. ATP Synthase uses this energy to create ATP

Question 3

Name 3 substrates that are required for the ETC to function

Answer 3

1. NADH or FADH2 (electron donor)
2. O2 (final electron acceptor)
3. ADP (to create ATP)

Question 4

How does the electron transport chain contribute to basal metabolic rate?

Answer 4

The electron transport chain loses some energy via proton leakage (protons flowing from intermembranous space to mitochondrial matrix without producing ATP)

this inherent energy loss is a large part of why we require energy input even during inactive states

Question 5

What is meant by a “high proton motor force”?

What are 2 consequences?

Answer 5

High proton motive force is when the concentration of protons in the intermembranous space is high, and it becomes more difficult to pump protons across.

This (1) slows respiration and (2) favors superoxide formation (oxygen picks up electrons to become O2-)

Question 6

How does CO affect the ETC?

Answer 6

• CO decreases oxygen delivery to tissues.
• Since there is no final electron acceptor available, ETC can’t function

Question 7

How do uncoupling proteins affect ETC?

Answer 7

Uncoupling proteins allow H+ gradient to dissipate (H+ flow into inner mitochondrial matrix without going through ATP synthase)

This prevents ATP production

Question 8

How do cells typically deal with superoxides?

Answer 8

Superoxides (a free radical) get converted to H2O2 by Superoxide Dismutase (SOD)