True or false: Holoenzymes consist of protein components and necessary coenzymes or cofactors, making them complete and functional enzymes.

Holoenzymes are indeed complete and functional enzymes comprised of both a protein component, known as the apoenzyme, and necessary cofactors or coenzymes. This combination is crucial because the active site formed by the holoenzyme is essential for catalyzing biochemical reactions effectively. In many cases, the cofactors, which may be metal ions or organic molecules like vitamins, play a significant role in enhancing the enzyme's activity or helping in the binding of the substrate.

In contrast, apoenzymes alone, without their respective cofactors or coenzymes, are typically inactive. The interaction between the protein structure and these additional components is what defines a holoenzyme and allows it to perform its biological function.

Other options mention incomplete components by either implying a lack of necessity for coenzymes or suggesting only protein is sufficient, which overlooks the essential role that these additional cofactors play in enzymatic activity and functionality. Thus, the statement about holoenzymes being composed of both protein and necessary cofactors or coenzymes is accurate, confirming the correct answer.