What type of protein speeds up chemical reactions in living organisms?

The type of protein that speeds up chemical reactions in living organisms is enzymes. Enzymes are biological catalysts that lower the activation energy required for reactions to occur, making those reactions happen more quickly and efficiently. They play a crucial role in various metabolic processes by facilitating biochemical reactions, such as digestion and cellular respiration.

Enzymes operate by binding to substrates and helping convert them into products through a series of steps that can be influenced by factors like temperature and pH. Unlike other proteins, enzymes can be reused multiple times in chemical reactions, which makes them highly efficient and essential for sustaining life.

The other options—carbohydrates, lipids, and hormones—have important functions in biological systems, but they do not act as catalysts to speed up chemical reactions in the same way enzymes do. Carbohydrates provide energy and structural support; lipids serve as energy storage and form cellular membranes; and hormones act as signaling molecules to regulate various physiological processes.