ETC

Question 1

ETC

Answer 1

Electron transport chain

Question 2

Where does ETC occur?

Answer 2

In mitochondria

Question 3

Where exactly does ETC take place?

Answer 3

In between the double membrane of a mitochondrion. Intermembrane space is involved, as well as inner mitochondrial membrane (cristae)

Question 4

What is the role of NADH and FADH2 in ETC?

Answer 4

NADH and FADH₂ donate electrons to the ETC, which generates a proton (H⁺) gradient across the membrane.

Question 5

What is ETC? What happens during ETC? (4 steps)

Answer 5

Process:

 1. Electron carriers (NADH, FADH₂) donate electrons to protein complexes (Complex I, II, III, IV).
 2. Protons (H⁺) are pumped across the membrane, creating a proton gradient.
 3. ATP Synthase. Protons flow back through ATP synthase, driving the phosphorylation of ADP to ATP.
 4. Oxygen acts as the final electron acceptor, combining with electrons and protons to form water.

Question 6

What is the final election acceptor in ETC?

Answer 6

Oxygen

Question 7

What is a proton gradient in ETC?

Answer 7

A proton gradient refers to a difference in proton concentration across a membrane.

It is typically created during the electron transport chain in cellular respiration. The proton gradient plays a key role in the formation of ATP through a process known as chemiosmosis.

Question 8

What is chemiosmosis?

Answer 8

Chemiosmosis is the process of diffusion of ions (usually H+ ions, also known as protons) across a selectively permeable membrane. As in osmosis, chemiosmosis leads to a concentration gradient of the diffusing ion across the membrane.

Question 9

Phosphorylation is

Answer 9

Addition of phosphorus
Fx ADP tp ATP in ETCs last step

Question 10

Net Gain in ETC

Answer 10

Theoretical yield of 30-32 ATP per glucose molecule (ideal conditions).

Question 11

TF

ETC is an aerobic process

Answer 11

True; uses Oxygen

Question 12

Why are foldings of mitochondrial inner membrane (cristae) important?

Answer 12

To increase the capacity of the mitochondrion to synthesize ATP, the inner membrane is folded to form cristae.

These folds allow a much greater amount of electron transport chain enzymes and ATP synthase to be packed into the mitochondrion.

Question 13

What protein complexes take part in ETC? How many are there and what roles do each one have?

Answer 13

The ETC consists of four primary complexes:
Complex I
(NADH: ubiquinone oxidoreductase), Complex II
(succinate: ubiquinone oxidoreductase),
Complex III
(cytochrome bc1 complex),
Complex IV
(cytochrome c oxidase).

Additionally, ATP synthase (Complex V) is involved in the final stage of ATP production.

The associated electron transport chain is NADH → Complex I → Q → Complex III → cytochrome c → Complex IV → O2 where Complexes I, III and IV are proton pumps, while Q and cytochrome c are mobile electron carriers.

Question 14

Nice definition for etc and cristae and proteins

Answer 14

The electron transport chain is a collection of membrane-embedded proteins and organic molecules, most of them organized into four large complexes labeled I to IV. In eukaryotes, many copies of these molecules are found in the inner mitochondrial membrane.

Question 15

Draw etc

Answer 15

Now!

Question 16

What does complex 1 do?

Answer 16

Complex I (NADH Dehydrogenase):

Input: NADH from the Krebs cycle donates electrons (e⁻).

Process:
NADH is oxidized to NAD⁺, releasing electrons.
These electrons are transferred to ubiquinone (Q) via iron-sulfur clusters.
Energy released pumps H⁺ protons from the mitochondrial matrix into the intermembrane space.

Effect: Establishes a proton gradient.

Question 17

What does complex 2 do?

Answer 17

Complex II (Succinate Dehydrogenase):
Input: FADH₂ (produced in the Krebs cycle) donates electrons.
Process:
FADH₂ is oxidized to FAD, transferring electrons directly to ubiquinone (Q).
No protons are pumped at this step, so FADH₂ contributes less to ATP production compared to NADH.

Question 18

What is Q?

Answer 18

Ubiquinone (Q):
A mobile electron carrier that shuttles electrons from Complex I and Complex II to Complex III.

Question 19

What does complex 3 do?

Answer 19

Complex III (Cytochrome bc₁ Complex):
Process:
Electrons from ubiquinone (Q) are transferred to cytochrome c, another mobile electron carrier.
Energy released pumps more H⁺ protons into the intermembrane space.

Question 20

What is Cytochrome c?

Answer 20

Cytochrome c:
A small, mobile protein that carries electrons from Complex III to Complex IV.

Question 21

What does complex 4 do?

Answer 21

Complex IV (Cytochrome c Oxidase):

Input: Electrons from cytochrome c.

Process:
Electrons are transferred to the final electron acceptor, oxygen (O₂).
O₂ combines with H⁺ protons to form water (H₂O).
This is why oxygen is essential for aerobic respiration.

Question 22

ATP Synthase

Answer 22

ATP Synthase (Complex V):
Process:
The proton gradient created by the complexes allows H⁺ protons to flow back into the mitochondrial matrix through ATP synthase.
This flow drives the production of ATP from ADP and inorganic phosphate (Pi).

Question 23

Oxidative phosphorylation

Answer 23

Oxidative phosphorylation is the production of ATP using the energy released by electrons as they move through the electron transport chain and the energy stored in the proton gradient (chemiosmosis). It occurs in the mitochondria and is the final, energy-producing step of cellular respiration.

Question 24

What is Pi?

Answer 24

Inorganic phosphate

Question 25

Whai is the net ATP Production of oxidative phosphorylation?

Answer 25

Around 30-32 ATP molecules per glucose molecule.