51 amino acids linked by peptide bonds. A biological catalyst that speeds up a chemical reaction by lowering the activation energy without itself being changed in a reaction and are protein in nature. Organic compounds that contain the atoms carbon, hydrogen, oxygen, nitrogen and phosphorus.

Let's break down the information provided in your problem statement: 1. **51 amino acids linked by peptide bonds**: This describes a polypeptide or protein that consists of 51 amino acids connected through peptide bonds. 2. **A biological catalyst that speeds up a chemical reaction by lowering the activation energy without itself being changed in a reaction and are protein in nature**: This describes enzymes. Enzymes are proteins that act as catalysts in biochemical reactions. 3. **Organic compounds that contain the atoms carbon, hydrogen, oxygen, nitrogen, and phosphorus**: This describes nucleic acids, such as DNA and RNA, which are essential for genetic information storage and transfer. Now, let's summarize the key points: - **Polypeptide/Protein**: A chain of 51 amino acids linked by peptide bonds. - **Enzymes**: Biological catalysts that are proteins and speed up reactions by lowering activation energy. - **Nucleic Acids**: Organic compounds containing C, H, O, N, and P, crucial for genetic information. If you have a specific question or need further elaboration on any of these topics, please let me know!