Lecture 5 - ETC

Question 1

What do we know before we initiate the ETC process

Answer 1

NADH and FADH2 are sitting in the mitochondria

Question 2

Step 1 of ETC

Answer 2

NADH gives Complex 1 (NADH dehydrogenase) its electrons and releases protons

• redox reactions occurs to excite complex, so protons are pumped across to the inter membrane space via proton motive force
• since electrons can cause oxidative stress they need to be moved along

Question 3

Step 2 of ETC

Answer 3

Complex II (Succinate dehydrogenase):

FADH₂ (produced in the Krebs cycle) donates electrons to Complex II, which also passes electrons to coenzyme Q10 but does not pump protons.

Electrons move to intermediate Coenzyme Q10 to reduce oxidative stress

Question 4

What is oxidative stress

Answer 4

the strong pull of oxygen directed towards electrons can make oxygen incredibly dangerous which can cause oxidative stress

Question 5

Step 3 of ETC

Answer 5

Q10 takes electrons from FADH2 and electrons enter, leading to redox reactions, which excite Q10

• but there is no transmembrane channels for H+ to be pumped to
• since electrons can cause oxidative stress they need to be moved along

Question 6

Step 4 of ETC

Answer 6

• Complex 3 receives electrons, electrons can enter Complex 3, leading to redox, exciting the complex, proton motive force moves H+ into IM space
• since electrons can cause oxidative stress they need to be moved along

Question 7

Step 5 of ETC

Answer 7

Moves to intermediate Cytochrome C
to reduce ox stress

Question 8

Step 6 of ETC

Answer 8

Electrons are passed to Complex 4, electrons enter, undergo redox, excite the complex, and protons are moved into IM space

Question 9

Step 8 of ETC

Answer 9

ATP synthase moves protons down cg
- that energy moves the ATP synthases proteins (makes a lot of ATP, END RESULT)

ADP + pi = ATP

Question 10

Step 7 of ETC

Answer 10

Complex 4 passes electrons to O2 to form H2O
- water is a byproduct
- oxygen is final electron acceptor

Question 11

Ubiquinone

Answer 11

hydrophobic molecule in the core of membrane

shuttles electrons from 1 and 2 to 3

Question 12

cytochrome c location

Answer 12

inter membrane space side of the membrane

shuttles electrons from 2 to 4

Question 13

in the etc, how do prosthetic groups

Answer 13

• facilitate electron transport, all the complexes bind a lot of prosthetic groups and they are redox-active cofactors that alternate between reduced and oxidized states as they accept electrons
• organized from high to low free energy
  HEME EXAMPLE: contains a central redox iron atoms that alternates with F2+ and F34+

Question 14

NADH
O2

Answer 14

NADH has a high PE because it has high electrons and that it has high energy electrons and the O2 is strongly electronegative can be reduced

Question 15

why does ubiquinone grab protons

Answer 15

to be neutral

Question 16

proton motive force

Answer 16

difference across the membrane produces stored energy

Question 17

oxidative phosphorylation

Answer 17

mode of ATP synthesis that is linked to oxidation of energy rich molecule

Question 18

what makes ionophores toxic

Answer 18

inhibit oxidative phosphorylation, inhibit ATP production

Question 19

when can ionophores be safer

Answer 19

• mitochondrial halotyopes, mitochondria will release energy to heat
• hibernating animals and newborn infants

Question 20

Placement of everything

Answer 20

NADH AND FADH2- MATRIX
COMPLEXES-IMM
PROTONS- PUMPED FROM MATRIX INTO INTERMEMBRANE SPACE