What are the main functions of proteins in the cell?

Proteins play crucial roles in various cellular functions, and one of their primary functions is providing structural support as well as catalyzing biochemical reactions. Structural proteins, such as collagen and keratin, contribute to the physical integrity and shape of cells, tissues, and organs, forming scaffolds that maintain cellular architecture.

Additionally, enzymes, which are proteins, act as catalysts in biochemical reactions, speeding up reactions vital to the metabolism of the cell. They lower the activation energy required for reactions, thereby enhancing the efficiency of complex biochemical pathways. This catalytic ability is fundamental to processes such as digestion, energy production, and DNA replication.

The other options highlight functions that are not predominantly carried out by proteins. For example, the replication of genetic material primarily involves nucleic acids, while generation of ATP is mainly associated with cellular respiration processes that involve various enzymes as well but not solely proteins. The creation of phospholipid bilayers is primarily a function of lipids rather than proteins. Thus, the correct choice emphasizes the dual role of proteins in providing structural support and facilitating biochemical reactions.