MadSci Network: Molecular Biology

Re: What elements make up the human body?

Date: Fri Dec 4 10:06:19 1998
Posted By: Michael Onken, MadSci Admin
Area of science: Molecular Biology
ID: 912733300.Mb

The mnemonic I learned was "C. Hopkin's Cafe", which noteably doesn't include Salt or several important metal ions, but I got this long ago from medical doctor rather than a biochemist, so go figure. I'll list the elements in the order of the mnemonic anyway, and follow it with the missing elements.

C - Carbon
H - Hydrogen
O - Oxygen
P - Phosphorus
K - Potassium
I - Iodine
N - Nitrogen
S - Sulphur
Ca - Calcium
Fe - Iron
Na - Sodium
Cl - Chlorine
Mg - Magnesium
Mn - Manganese
Zn - Zinc
Others -Trace amounts of Selenium (Se), Cobalt (Co), Chromium (Cr), Copper (Cu) and probably some others.

The building blocks of life use these elements as follows:

Carbohydrates (sugar, starch, etc.) use carbon (C), hydrogen (H) and oxygen(O), almost equally, and are often abbreviated as "CHO's".

Proteins use carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sulphur (S) for their building blocks, and they are often "decorated" with phosporus (P).

Fats are almost entirely carbon (C) and hydrogen (H) with very little oxygen (O). The "Phospho-lipids" that make up the cell walls also contain phosphorus (P) and usually some nitrogen (N).

Nucleic Acids (DNA and RNA) are composed of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and phosphorus (P).

Most of the body (over 80%) is salt water: sodium chloride (NaCl) and a little potassium chloride (KCl) dissolved in water (H2O).

Bone is made of calcium (Ca), phosphorus (P), oxygen (O), and hydrogen (H).

The other elements are used by protein "enzymes" to run most of the body's chemical reactions: magnesium (Mg) and manganese (Mn) are important for DNA synthesis; Iron (Fe) is required for carrying oxygen in the blood and using it in the cell; many proteins need calcium (Ca) and zinc (Zn) to stay folded properly for them to work; and iodine (I) and the trace elements have more specific jobs in making hormones and coordinating other reactions. The known enzymes that use each trace element can be searched in ExPASy's ENZYME database.

(If you look at the Periodic Table, you'll notice that most of the body is made up of a group of elements from the upper right corner of the table collectively called the "Nonmetals".)

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