ETS/Chemiosmosis

Question 1

site of electron transport and ATP synthesis

Answer 1

inner membrane of mitochondria

Question 2

cristae

Answer 2

the folds in the inner membrane of the mitochondria. more folds = more surface area

Question 3

what’s the purpose of the electron transport system

Answer 3

to harvest energy from the NADH and FADH2 generated in glycolysis and TCA, maintain proton gradient in the mitochondria b/w matrix and intermemebrane space so that the chemiosmotic synthesis of ATP can proceed.

Question 4

Overview of oxidative phosphorylation

Answer 4

1. NADH generated in the TCA cycle passes electrons to the first complex of the electron transport system, which passes them on
2. Three of the four complexes in ETS change conformation as they accept electrons
3. The conformation change drives active transport of protons into the inter membrane compartment
4. Dissipation of this proton gradient by facilitated diffusion through channels in the ATP Synthase provides energy to drive ATP synthase.

Question 5

Overall reaction of ETS

Answer 5

2 NADH + 2H+ + O2 –> NAD+ + H2O

FADH2 + O2 –> FAD + H2O

Question 6

ubiquninone

Answer 6

a mobile carrier in the ETS that carries electrons and protons from Complex 1/2 to Complex 3. When ubiquinone accepts 2 electrons and 2 protons it becomes ubiquinol. (ketone –> alcohol)

Question 7

Complex 1

Answer 7

accepts electrons and protons from NADH and passes them to ubiquinone

Question 8

Complex 2

Answer 8

accepts electrons from FADH2 and passes them onto ubiquinone. Contains the TCA cycle component enzyme, succinylcholine dehydrogenase. It does not pump protons. It is the only TCA cycle enzyme that is membrane attached.

Question 9

Complex 3

Answer 9

accepts 2 electrons from ubiquinone but doesn’t have a place for protons, so it leaves protons off on intermembrane space side.

Question 10

cytochrome c

Answer 10

a mobile carrier that takes electrons from complex 3 to complex 4

Question 11

complex 4

Answer 11

puts electrons onto oxygen to form H2O. The hydrogens it takes from the matrix, contributing to proton gradient (low in matrix, high in inter membrane space)

Question 12

structure of protein complexes

Answer 12

multi-subunit integral membrane proteins on inner membrane and they accept electrons onto iron or copper.

Question 13

Pure electron carriers

Answer 13

Complexes 3 and 4 do not have space for the protons but only the electrons. Cytochrome C shuttles pure electrons between complexes 3 and 4, so it is also a pure electron carrier.

Question 14

Which complexes pump protons

Answer 14

Complexes 1, 3, and 4. Complex 2 does not.

Question 15

mobile carriers

Answer 15

ubiquninone and cytochrome c can carry electrons and protons through the bilayer between the complexes.