Introduction to Biochemistry, Page 4

Elements of life
•Elements H, O, N, P, S are also common

•Metal ions (e.g. K+, Na+, Ca++, Mg++, Zn++, Fe++) play 

important roles in metabolism

•Together, about 30 elements are essential for life

Elemental composition of Life: 

Unique Role of Carbon

•Biomolecules are carbon-based

Biological Molecules 

Typically Have Several Functional Groups

Structure of Biological Molecules is

Important

•The function of molecules strongly depend on three-dimensional structure

Stereoisomers have Different Biological 
Properties

•Cis and trans isomers have also different physical and chemical properties

Optical Isomers have Different Biological Properties

•Enantiomers have identical physical properties (except 

regard to polarized light) and react identically with achiral 

reagents.

•Diastereomers have different physical and chemical

R = rectus (right-handed)

S = sinister (left-handed)

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