Cell Biology/Introduction/The elements of life

The various elements that make up the cell are: 59% Hydrogen (H) 24% Oxygen (O) 11% Carbon (C) 4% Nitrogen (N) 2% Others - Phosphorus (P), Sulfur (S), etc. The difference between these elements is their respective atomic weights, electrons, and in general their chemical properties. A given element can only have so many other atoms attached. For instance carbon (C) has 4 electrons in its outer shell and thus can only bind to 4 atoms; Hydrogen only has 1 electron and thus can only bind to one other atom. An example would be Methane which is CH4. Oxygen only has 2 free electrons, and will sometimes form a double bond with a single atom, which is an 'ester' in organic chemistry (and is typically scented). Methane Water Methanol (Methyl Alcohol) <nowiki> H | H-C-H | H </nowiki> <nowiki> H H \ / O </nowiki> <nowiki> H | H-C-O-H | H </nowiki> As for the organic molecules that make up a typical cell: 50% protein 15% nucleic acid 15% carbohydrates 10% lipids 10% Other Here is a list of Elements, symbols, weights and biological roles. ElementSymbolAtomic WeightBiological RoleBromineBr79.9Defense and pigmentation in certain marine organisms, esp. algae.CalciumCa40.1Bone; muscle contraction, second messengerCarbonC12.0Constituent (backbone) of organic moleculesChlorineCl35.5Digestion and photosynthesisChromiumCr52.0Metabolism of sugars and lipids in humans.CopperCu63.5Part of Oxygen—carrying pigment of mollusk blood.FluorineF19.0For normal tooth enamel developmentHydrogenH1.0Part of water and all organic moleculesIodineI126.9Part of thyroxine (a hormone)IronFe55.8Hemoglobin, oxygen caring pigment of many animalsMagnesiumMg24.3Part of chlorophyll; essential cofactor for many enzymes of energy metabolism.ManganeseMn54.9Essential to some enzyme actions.NitrogenN14.0Constituent of all proteins and nucleic acids.OxygenO16.0Respiration; part of water; and in nearly all organic molecules.PhosphorusP31.0Constituent of DNA and RNA backbones; high energy bond in ATP.PotassiumK39.1Generation of nerve impulses.SeleniumSe79.0For the working of many enzymes.SiliconSi28.1Diatom shells; grass leaves.SodiumNa23.0Part of Salt; nerve conductionSulfurS32.1Constituent of most proteins. Important in protein structure: Sulfide bonds are strong.ZincZn65.4Essential to alcohol oxidizing enzyme.