ets

Question 1

which complexes pump protons across the inner membrane? how many from each complex?

Answer 1

• 1: 4 H+
• 3: 2 H+
• 4: 4 H+

Question 2

what cofactors are associated with complex 1 and 2?

Answer 2

• 1: NADH

- 2: FADH2

Question 3

where are the H+ pumped from and into?

Answer 3

from the mitochondrial matrix to the intermembrane space

Question 4

what is complex 5? what does it do?

Answer 4

• ATP synthase
• spontaneously takes the H+ from the intermembrane space and pumps them back into the matrix to form ATP from Pi and ADP

Question 5

what makes up the ETS? what makes up oxidative phosphorylation?
- define each as from start to finish

Answer 5

• ETS: Complex 1 to 4

- OP: complex 1 to 5 (ATP synthase)

Question 6

what enzyme is associated with complex 1?

Answer 6

NADH dehydrogenase

Question 7

describe the relationship between complex 1 and CoQ

Answer 7

CoQ binds complex 1 and accepts the electrons NADH donates, forming NAD+

Question 8

what is CoQ?

Answer 8

• non protein complex of ETS
• can undergo oxidation and reduction reactions to make it an electron shuttle for complex 1 –> 3 and complex 2 –> 3
• lipid soluble, so it can diffuse from complex to complex through the inner mitochondrial membrane

Question 9

what enzyme is associated with complex 2?

Answer 9

• succinate dehydrogenase

Question 10

what is the citrate cycle enzyme?

Answer 10

• succinate dehydrogenase from complex 2

Question 11

where is complex 2 located? what makes this different than complex 1, 3 and 4

Answer 11

• complex 2 is located in the mitochindrial matrix
• complex 1, 3, 4 and 5 are located in the innermembrane of the mitochondria
  
  • this is why complex 2 does NOT pump proton across the inner membrane

Question 12

what happens to succinate in the ETS? where does this happen?

Answer 12

• succinate becomes fumarate

- happens in complex 2

Question 13

what happens in complex 3?

Answer 13

• electrons from CoQ reduce the HEME iron from Fe3+ to Fe2+

- electrons donated by CoQ drive proton pumping in cytochrome c

Question 14

describe cytochrome c

Answer 14

• a soluble protein that transports electrons from complex 3 to 4
• contains heme, requires iron

Question 15

what enzyme is associated with complex 4?

Answer 15

cytochrome oxidase

Question 16

what happens in complex 4?

Answer 16

• accpets electrons donated by cytochrome c
• complex requires iron and copper because it contains an iron-copper complex that is responsible for storing donated electrons
• uses electrons to reduce O2 to H2O and to drive proton pumping

Question 17

when does the ETS end?

Answer 17

when O2 is reduced to H2O using electrons initially donated by NADH and/or FADH2

Question 18

does the ETS operate in reverse? can it be inhibited?

Answer 18

• does not operate in reverse, but can be inhibited