CHM360 Final Study Guide
What is the outcome of the Q cycle?
1 net QH2 used (took in 2, released 1)
How can inhibition of oxidative phosphorylation occur
1. Inhibition of the ETC inhibits the formation of proton-motive force 2. Inhibition of ATP synthase inhibits proton flow and prevents electron transfer 3. Uncouplers carry protons across the inner mitochondrial membrane so a proton gradient can't form 4. Inhibition of ATP-ADP translocase
How many degrees does the gamma subunit rotate to hydrolyze 1 ATP? How many are released in a full rotation?
120 degrees, 3 (=360/120)
What happens in the first half of the Q cycle?
2 e- bound to QH2 are transferred, one to cytochrome c and one to Q to form semiquinone -Q dissociates and enters the Q pool
T (tight form)
ATP is synthesized from ADP and Pi
What is ATP synthase
ATP synthase is composed of a proton-conducting unit and a catalytic unit. Proton flow through ATP synthase leads to the release of tightly bound ATP.
What is respiration?
An ATP generating process in which an inorganic compound such as molecule oxygen serves as the ultimate electron acceptor
Flavin molecule
An electron transport chain carrier
What happens in the second half of the Q cycle?
Another QH2 gives up 1e- to cytochrome c and another gives an e' to semiquinone to form QH2 Both Q and QH2 dissociate
What two factors make up proton motive force?
Chemical gradient (1.4 pH units lower outside than inside) Charge gradient (.14V outside, - inside)
What who processes make up cellular respiration?
Citric acid cycle and oxidative phosphorylation
What path does NADH take?
Complex I, Coenzyme Q, Complex III, Cytochrome C, Complex IV, O2
What path does FADH take?
Complex II, Coenzyme Q, Complex III, Cytochrome C, Complex IV, O2
What is the purpose of electron flow in the electron transport chain?
Creates a proton gradient, whose energy is converted into ATP by ATP synthase
What is the purpose of shuttles
Electrons from cytoplasmic NADH enter the mitochondria by shuttles
ATP-ADP translocase
Enables the exchange of cytoplasmic ADP for mitochondrial ATP
What is ubiquinol?
Entry point for electrons from FADH2 of flavoproteins
What are the shuttles?
Glycerol phosphate shuttle in the muscles Malate-aspartate shuttle in the heart and liver
Where does the flow of electrons from NADH and FADH2 to O2 occur?
In the electron transport/respiratory chain
Where does uncoupling occur and what protein facilitates it?
In the mitochondria in brown fat, regulated by uncoupling protein-1 aka thermogenin
What is the purpose of the Q cycle?
It funnels electrons from a two electron carrier to a one-electron a carrier and pumps protons
Reduction potential
Measure the molecule's tendency to donate or accept electrons
Describe the permeability of the mitochondrial membrane
Mitochondria are bound by a double membrane 1. The outer membrane is permeable to most small ions and molecules due to the presence of porins 2. The inner membrane is impermeable to most molecules, but transporters allow for metabolite exchange
Coenzyme Q
Mobile electron carrier derived from isoprene that binds protons (QH2) as well as electrons, and can exist in several oxidation states
L (loose) form
Nucleotides are trapped in the beta subunit
O (open form)
Nucleotides can bind to or be released from the beta subunit
What is the end electron acceptor in the electron transport chain?
O2
What kind of reactions occur in the electron transport chain?
Oxidation reduction
What process captures the energy of high-energy electrons to sythesize ATP?
Oxidative phosphorylation
What does ubiquinone become in Complex I?
Proceeds to ubiquinol (QH2) through a semiquinone intermediate
What is a positive E0 indicative of?
Strong oxidating agent that readily accepts electrons
What is a negative E0 indicative of?
Strong reducing agent that readily donates electrons
Substrate level phosphorylation vs oxidative phosphorylation
Substrate-level phosphorylation is directly phosphorylating ADP with a phosphate and energy provided by a coupled reaction Oxidative phosphorylation is when ATP is generated from the oxidation of NADH and FADH2 and the subsequent transfer of electrons and pumping of protons.
How are ATP and ADP transport related to the mitochondria?
The entry of ADP to the mitochondria is coupled to the exit of ATP through the use of ATP-ADP translocase
Where is the electron transport chain?
The mitochondria
What determines the number of protons required to synthesize a molecule of ATP?
The number of C rings
What is proton motive force?
The proton gradient generated by the oxidation of NADH and FADH2 that powers the synthesis of ATP
When does nonshivering thermogenesis occur?
When electron transport is uncoupled from ATP synthesis and heat is generated
