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) |
|---|---|---|
H | H-C-H | H |
H H \ / O |
H | H-C-O-H | H |
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.
| Element | Symbol | Atomic Weight | Biological Role |
|---|---|---|---|
| Bromine | Br | 79.9 | Defense and pigmentation in certain marine organisms, esp. algae. |
| Calcium | Ca | 40.1 | Bone; muscle contraction, second messenger |
| Carbon | C | 12.0 | Constituent (backbone) of organic molecules |
| Chlorine | Cl | 35.5 | Digestion and photosynthesis |
| Chromium | Cr | 52.0 | Metabolism of sugars and lipids in humans. |
| Copper | Cu | 63.5 | Part of Oxygen—carrying pigment of mollusk blood. |
| Fluorine | F | 19.0 | For normal tooth enamel development |
| Hydrogen | H | 1.0 | Part of water and all organic molecules |
| Iodine | I | 126.9 | Part of thyroxine (a hormone) |
| Iron | Fe | 55.8 | Hemoglobin, oxygen caring pigment of many animals |
| Magnesium | Mg | 24.3 | Part of chlorophyll; essential cofactor for many enzymes of energy metabolism. |
| Manganese | Mn | 54.9 | Essential to some enzyme actions. |
| Nitrogen | N | 14.0 | Constituent of all proteins and nucleic acids. |
| Oxygen | O | 16.0 | Respiration; part of water; and in nearly all organic molecules. |
| Phosphorus | P | 31.0 | Constituent of DNA and RNA backbones; high energy bond in ATP. |
| Potassium | K | 39.1 | Generation of nerve impulses. |
| Selenium | Se | 79.0 | For the working of many enzymes. |
| Silicon | Si | 28.1 | Diatom shells; grass leaves. |
| Sodium | Na | 23.0 | Part of Salt; nerve conduction |
| Sulfur | S | 32.1 | Constituent of most proteins. Important in protein structure: Sulfide bonds are strong. |
| Zinc | Zn | 65.4 | Essential to alcohol oxidizing enzyme. |