Question

RT ANSWER. Complete all questions in this section Uncentration "questions in this section with a short, clear, concise response. 21) Describe how excited electrons captured by NADH phosphorylation. " electrons captured by NADH and FADH2 result in synthesis of ATP by oxidative

Answer 1

• The mechanism of oxidative phosphorylation occurs in mitochondria of live cells.
• Electrons are transported across various components of electron transport chain (ETC), resulting in series of oxidation-reduction reactions within the membrane bound complexes in mitochondria (complex I, II, III, IV).

Complex I: NADH dehydrogenase:

Complex II: Succinate dehydrogenase

Complex III: Ubiquinol cytochrome C oxidoreductase

Complex IV: Cytochrome C oxidase

Complex V: ATP synthase.

• Electrons are transported across various components of electron transport chain (ETC), resulting in series of oxidation-reduction reactions. NADH and FADH2 are electron donors; their oxidation creates high concentration energy from electrons.
• This energy is used to pump proton from matrix to inter membrane space.
• Flow of protons creates and electrochemical gradient, which is used to generate ATP.
• The enzyme ATP synthase, is responsible for conversion of transmembrane proton potential difference into “energy currencies of cells” in form of ATP.

Thus considering NADH:

· The flow of electrons from electron donors to terminal electron acceptor (like oxygen) releases energy, creating a proton motive force (PMF)

NADH + 1/2 O2 + H+ - > H2O + NAD+ (delta G = -52.6 kcal/ mol)

While energy is utilized during endergonic reaction, as in formation of ATP.

ADP + Pi + H+ -     > ATP + H2O (delta G = 7.3 kcal/ mol)