The construction of cells

•DNA or RNA

•Protein

•Carbohydrates

•Lipid etc.

Isoelectric point of protein

• pH < pI

• Protein is positive charge.

• pH > pI

• Protein is negative charge.

Amino Acid Sequences of Cytochromes c from 38 species

A phylogenetic tree of cytochrome c

One subunit of the enzyme glyceraldehyde-3-phosphate dehydrogenase from Bacillus stearothermophilus.

Major biological functions of protein

• Catalytic proteins: A+B C

• Structural proteins

• Transport proteins

• Regulatory proteins

• Protective proteins : antibodies

enzyme

The activity of every enzyme is specific.