Question

Label the diagram. Most of the ATP that is produced by organisms happen in the cells mitochondria, specifically in the electron transport system. Using the diagram, explain how ATP is generated and why if the supply of wygen is cut off, the organism or the cell dies (10 pts) In 1933 to 1938, DNP dinitrophenol) was used for weight loss and was the cause of death of some individuals. Use the diagram toxplain how DNP was used for weight loss (eg, the mechanius) and why it killed people. 15 pts)

Answer 1

(A) Electron transport system is composed of complexe I-Iv and ATP synthase, in which electron transfers from elctron donors to electron acceptors, and coupled with movement of proton across cell membrane. Due to this proton movement, a proton gradient is established and consequently ATP is formed.

Complex I. complex I is the NADH ubiquinone (Q) oxidoreductase. Here, two electrons transfered to ubiquinone from NADH. Lipid soluble ubiquinone now reduced to ubiquinol (QH2). Complex I producing proton gradient by the movement of 4 protons across the cell membrane.

Complex II. In this complex extra electrons are trasferred to Q from succinate via FAD. No any proto is transported by complex II in intermebrane space.

Complex III. Two electrons are are removed from QH2 and transported to two molecules of cytochromes. The two other electrons move to the Q part of ubiquinone is reduced to quinol. A proton gradient is formed here.

Complex IV. Here, four electrons are moved from cytochromes to molecular oxygen and producing water. Eight protons are removed from mitochondrial matrix, out of Eight, four protons move across the membrane.

The movement of protons from mitochondrial matrix formed a electrochemical (proton) gradient, This proton gradient is used by the F0F1 complex of ATP synthase to form ATP by oxidative phosphorylation. Protons in the inter-membrane of mitochondria enters into the ATP synthase through a subunit channel. Then protons transported to the c subunits.After c subunits, protons enters matrix using a subunit channel that opens in the mitochondrial matrix. During this reflux free energy produced. This free energy is used for ATP synthesis, catalyzed by the F1 component of the complex.

When oxygen supply is cut off cell dies because movement of electron is blocked due to which no any ATP formation takes place consequently cell dies.

(B) DNP inhibits the ATP synthesis due to which death occurs. DNP causes leakage of protons from mitochondrial membrane and proton bypss the ATP synthase. due to which less ATP formation. Energy produced during respiration is wasted as heat thats why DNP was used for weight loss.