Final answer:
Proteins in the mitochondrion are synthesized both in the cytosol and the mitochondrial matrix. Proteins made in the cytosol are targeted and imported into the mitochondria post-translationally. Mitochondria have their own DNA and ribosomes for protein synthesis as well.
Step-by-step explanation:
The proteins in the mitochondrion are synthesized both in the cytosol and within the mitochondrial matrix. This is because mitochondria have their own ribosomes and DNA, enabling them to manufacture some proteins internally. Moreover, many proteins required by the mitochondria are initially synthesized in the cytosol and later transported into the mitochondrion. These proteins contain specific signaling sequences that target them to the mitochondria, where they are imported post-translationally. The process of targeting and importing these proteins involves the recognition of their signal peptides by receptor proteins located on the mitochondrial outer membrane.
Once recognized, the proteins are translocated across the membranes, where they can reach the mitochondrial matrix or become integrated into the inner membrane, often involving the area with the cristae. It is significant to note that some mitochondrial proteins originate from nuclear DNA and are subsequently directed to the mitochondria, emphasizing the dual collaboration between the cytosolic and mitochondrial protein synthesis machinery for proper mitochondrial function and cellular energy production.