Q#1: If you add mitochondria to an oxygen electrode chamber what happens to the
oxygen concentration in the chamber?
Oxygen is consumed, popular way in measuring cellular respiration is the rate of
consumption of oxygen.
Adding NADH, oxygen consumption will go up, isolated mitochondria don’t have a
source of substrate no pyruvate going into mitochondria, when you put NADH in,
now has substrate. Quickly depletes levels of NADH within mitochondrial matrix,
rate of electron transport (oxygen consumption) should go up.
Adding ADP+, rate of oxygen consumption goes up even more.
*Respiratory control: Rate of electron transport will be dependent on availability of
*If there’s no ADP around, proton gradient becomes very high; pH in
intermembrane is very low, harder for complexes to pump protons into space with
already a lot of protons, limits rate of electron transport. No substrate to drive
phosphorylation of ADP, high gradient, no ADP in mitochondria, protons won’t flow
*Even though two independent processes (ETC and ATP synthase), they are coupled
in a normal system, they influence each other.
Adding uncoupler, rate goes up. Giant holes in membrane, protons escape, zero
proton gradient. Now it’s easy to pump protons across, no pH difference. There
nothing holding back electron transport now. Electron transport goes as fast as
possibly can. Protons being pumped but they are leaking right back in.
*Uncoupled rate is highest rate of oxygen consumption.
Q#2: In plant cells there are two ATP generating organelles- mitochondria and
chloroplasts. Compared to animal cells how may mitochondria cells be different?
A. They are not