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Basics of Biology

Basic Chemistry For Biology

What are the most important elements in living systems?

The most important elements in living systems include oxygen, carbon, hydrogen, nitrogen, calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium, and iron. These elements are essential to life due to their cellular function. The following lists the most common and important elements in living organisms:

Element

Percent of Humans by Weight

Functions in Life

Oxygen

      65

Part of water and most organic molecules; molecular oxygen

Carbon

      18

Backbone of organic molecules

Hydrogen

      10

Part of all organic molecules and water

Nitrogen

        3

Component of proteins and nucleic acids

Calcium

        2

Part of bone; essential for nerves and muscles

Phosphorus

        1

Part of cell membranes and energy storage molecules; part of bone

Potassium

           0.3

Important for nerve function

Sulfur

           0.2

Structural component of some proteins

Sodium

           0.1

Primary ion in body fluids; essential for nerve function

Chlorine

           0.1

Major ion in body fluids

Iron

Trace

Component of hemoglobin

Magnesium

Trace

Cofactor for enzymes; important to muscle function


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