Chemical Elements for Life
The chemical elements most prominent in building the structures of the molecules of life are carbon, hydrogen, oxygen, nitrogen, phosphorous and sulfur, sometimes represented mnemonically as CHONPS. These elements combine in a vast number of molecules involved in life processes. Their fitness for making these compounds is related to their relative electronegativities which contribute to their ease of combination.
Carbon: Carbon is the foundational element for all life on Earth. It's capacity to form four bonds makes possible an almost limitless variety of compounds.
Oxygen: Oxygen is the most abundant element in the human body at 65%. It is abundant partly because the body is up to 60% water, but is also a constituent of most large biological molecules and is continually being exchanged in the process of metabolism and respiration.
Hydrogen: Hydrogen with oxygen is abundant in the body because it is up to 60% water.
Nitrogen: Nitrogen is not abundant on the Earth, but is crucial in life processes.
Phosphorus: Phosphorus is not so abundant, but is crucial in the energy sources for life processes
Sulfur: Sulfur has many structural roles in proteins.
Calcium: Calcium is a key component of bones and calcium ions also handle information in neural processes. As a chemical messenger, it has not only high speed but also the ability to bind to another molecule in the cell like a protein with high specificity to enact a conformational change. Calcium and magnesium can accomplish this, but calcium is superior for the role, binding many times more strongly than magnesium.
The Role of Metal Atoms in Body Chemistry
Although present in relatively small amounts, metal atoms play a surprisingly important role in the chemistry of life. About a third of the enzymes in the body involve a metal ion as an essential participant. From the electron transport chain to the maintaining of membrane potentials of cells, metals play essential supporting roles for the atoms involved in the major structures of life.
Sodium: Sodium binds weakly to organic compounds and sodium ions are small and highly mobile, ideally suited for moving electric charge at high speeds. Sodium and potassium are the only ions whose speed is unimpeded by a tendency to bind to organic compounds.
Magnesium is present in every cell type in every organism. Magnesium enyzmes are necessary for the catalytic action of more than 300 enzymes.
Potassium: Potassium binds weakly to organic compounds and potassium ions are small and highly mobile, ideally suited for moving electric charge at high speeds. Potassium and sodium are the only ions whose speed is unimpeded by a tendency to bind to organic compounds.
Manganese: Manganese is important in plant photosynthesis.
Iron: One of the most important metals in biological processes, iron is a key to oxygen transport by hemoglobin, to electron transport on the way to ATP production, and part of a catalyst for the fixation of nitrogen in plants.
Cobalt: Cobalt and nickel are sometimes referred to as evolutionary relics because of their frequent appearance in ancient anaerobic bacteria. Vitamin B12 has a single atom of cobalt. Current uses involve vitamin B12-dependent enzymes.
Copper: A key element in the electron transport chain which leads to the energy molecule ATP in the cell.
Zinc: There is typically only about 3 grams of Zinc in the body, but it is present in over 300 enzymes. It has a crucial role in converting CO2 to H2CO3 for transport to the lungs.
Molybdenum: Molybdenum is the key metal ion component in four important enzymes in our bodies. It is the key metal ion involved in nitrogen fixation in plants.
Chemistry of elements
Denton Miracle of the Cell, Ch 6