Exploring the molecular pathways and physiological importance of carbon, nitrogen, and phosphorus in dierent biological systems has highlighted their contributions to life’s fundamental processes. Carbon forms the framework of biological molecules, nitrogen is critical for proteins and nucleic acids, and phosphorus is essential for nucleic acids, membrane structure, and energy metabolism. Cellular membranes contain phospholipids which provide structure and specic physiological characteristics to support the molecular pathways of the cell. Which of the following models represents the correct arrangement of phosphorus within a phospholipid?
Water molecules are composed of the atoms hydrogen and oxygen, which are held together by covalent and hydrogen bonds. Which of the following models best demonstrates the arrangement of hydrogen bonds between water molecules? (Hydrogen bonds are depicted by dashed lines.)
