BackThe Chemical Context of Life: Atomic Structure and Elements in Biology
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The Chemical Context of Life: Atomic Structure
The Elements of Life
All living organisms are composed of matter, which is anything that occupies space and has mass. The study of the elements and their atomic structure is fundamental to understanding biological processes.
Matter: Anything that takes up space and has mass.
Elements: Pure substances that cannot be broken down into other substances by chemical reactions.
There are 92 naturally occurring elements, but only about 20–25% are essential for life. These are called essential elements.
Major elements in living organisms: Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N) make up approximately 96% of living matter.
The remaining 4% of living matter is primarily composed of calcium (Ca), phosphorus (P), potassium (K), and sulfur (S).
Trace elements are required by organisms in only minute quantities but are still essential for proper biological function.
Table: Elements in the Human Body
The following table summarizes the main elements found in the human body and their approximate contribution to body mass (including water):
Element | Symbol | Percentage of Body Mass (including water) |
|---|---|---|
Oxygen | O | 65.0% |
Carbon | C | 18.5% |
Hydrogen | H | 9.5% |
Nitrogen | N | 3.3% |
Calcium | Ca | 1.5% |
Phosphorus | P | 1.0% |
Potassium | K | 0.4% |
Sulfur | S | 0.3% |
Sodium | Na | 0.2% |
Chlorine | Cl | 0.2% |
Magnesium | Mg | 0.1% |
Trace elements (less than 0.01% of mass) include: boron (B), chromium (Cr), cobalt (Co), copper (Cu), fluorine (F), iodine (I), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se), silicon (Si), tin (Sn), vanadium (V), zinc (Zn).
Key Definitions and Concepts
Essential elements: Elements required for an organism to survive, grow, and reproduce.
Trace elements: Elements required by an organism in very small amounts.
Atomic structure: The arrangement of subatomic particles (protons, neutrons, electrons) within an atom, which determines the properties of each element.
Examples and Applications
Oxygen is essential for cellular respiration, a process that releases energy from food.
Calcium is important for bone structure and muscle function.
Iron (a trace element) is a key component of hemoglobin, which transports oxygen in the blood.
Additional info: Understanding the chemical composition of living organisms provides the foundation for studying more complex biological processes, such as metabolism, genetics, and cellular structure.
