Mitochondria are the powerhouse of a cell because this is where the bulk of ATP needed for the normal functioning of the cell is produced.
The membrane-bound electron transport chain carrier molecules, proton pumps embedded in the inner mitochondrial membrane and mitochondrial ATP synthase must be present in the mitochondria for the production of ATP.
The citric acid cycle takes place in the mitochondria. Therefore, it is a must that the enzymes for the citric acid cycle be present in the mitochondria for the cycle to take place.
Glycolysis takes place in the cytoplasm of the cell. Therefore, it is not a must for enzymes of glycolysis to be present in the mitochondria.