Cell metabolism is necessary for the production of energy for the cell and therefore its survival and includes many pathways and also sustaining the main cell organelles such as the nucleus, the mitochondria, the cell membrane etc. For cellular respiration, once glucose is available, glycolysis occurs within the cytosol of the cell to produce pyruvate. Pyruvate undergoes decarboxylation using the multi-enzyme complex to form acetyl coA which can readily be used in the TCA cycle to produce NADH and FADH. These products are involved in the electron transport chain to ultimately form a proton gradient across the inner mitochondrial membrane. This gradient can then drive the production of ATP and  during oxidative phosphorylation. Metabolism in plant cells includes photosynthesis which is simply the exact opposite of respiration as it ultimately produces molecules of glucose.