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Biology LibreTexts

1.II:. Intro to Biochemistry

A. What is biochemistry and who needs it?

Literally "Biochemistry" is the chemistry of life. This is synonymous with "Molecular Biology", but traditionally biochemistry has dealt more with the study of proteins and smaller biomolecules and molecular biology has dealt more with gene expression and associated molecules. The two are often used together now as in the major at U. C. Davis, "Biochemistry and Molecular Biology". Because biomolecules are the underlying basis for all aspects of the physiology and behavior of living systems, anyone who chooses to work in a biologically-related field has a need for an understanding of biochemistry.

B. Molecules in an E. coli cell

Compound % weight ave. MW #/cell # of kinds comment
\(H_2O\) 70 18 \(4\times 10^{10}\) 1  
Ions (Na,K,SO4, etc.) 1 40 \(2.6 \times 10^8\) 20 major exampleNa+ ~0.050 M
Carbohydrates 3 150 \(2 \times 10^8\) 250  
Amino Acids 0.4 120 \(3 \times 10^7\) 20 main ~120 total  
Nucleotides 0.4 300 \(1.2 \times 10^7\) 5 main ~100 total  
Lipids 2 750 \(2.5 \times 10^7\) 50  
Proteins 15 40,000 \(1 \times 10^6\) 4,288 35 -85,000 in humans!
RNA 6 \(10^6\) \(2 \times 10^4\) ~2,000 35 -85,000 in humans
DNA 1 \(2.5 \times 10^9\) \(1\, (4)\) 1 46 @ 5 \times 10^10 (human)