Final answer:
Mitochondria require chaperone proteins like HSP70 to help fold proteins that are not coded within their own DNA, but are specified by mRNA and synthesized elsewhere, usually in the cytosol.
Step-by-step explanation:
The organelle that requires chaperones because the proteins needed are not coded is the mitochondrion. Chaperone proteins such as HSP70 are essential for assisting in the folding of proteins that are destined for the mitochondria. Despite being properly specified by mRNA, proteins could misfold under abnormal conditions such as incorrect temperature or pH levels.
Some proteins that are synthesized in the cytosol and are destined for the mitochondria contain oligopeptide signals that guide them to the correct organelle. The HSP70 chaperone in the mitochondria then aids in refolding the protein into its functional form.