Free palmitate is activated to its coenzyme A derivative (palmitoyl-CoA) in the cytosol before it can be oxidized in the mitocho
ndrion. If palmitate and [14C]coenzyme A are added to a liver homogenate, palmitoyl-CoA isolated from the cytosolic fraction is radioactive, but that isolated from the mitochondrial fraction is not. Explain.
The cytosolic and mitochondrial pools of CoA are kept separate, and no radioactive CoA from the cytosolic pool enters the mitochondrion.
Explanation:
Fatty acyl group condensed with CoA in the cytosol are first transferred to carnitine and in this process, CoA is released.
After this, it is transported into the mitochondrion, where it is again condensed with CoA.
In this way, the cytosolic and mitochondrial pools of CoA are kept separate, and due to this reason, no radioactive CoA from the cytosolic pool enters the mitochondrion.
Therefore, according to the given question, the C14 CoA that is added into the liver homogenate along with palmitate shows cytosolic radioactive fraction but not mitochondrial as in the mitochondria a different CoA joins palmitate and not the one containing C14.
Most animals in Animalia have backbones, but not all. The correct answer would be C, because all organisms in Animalia are heterotrophs which means that they depend on other organisms (like animals and plants) for food.
