Show, by Lewis electron-dot structures of the appropriate portions of the molecule, where electrons are lost in

Question:

Show, by Lewis electron-dot structures of the appropriate portions of the molecule, where electrons are lost in the following conversions:
(a) Pyruvate to acetyl-CoA
(b) Isocitrate to a-ketoglutarate
(c) a-Ketoglutarate to succinyl-CoA
(d) Succinate to fumarate
(e) Malate to oxaloacetate