Living things contain DNA The genetic instructions of all living organisms is contained in molecules of deoxyribonucleic acid. DNA contains instructions that are used by cells to produce proteins. The vast array of different chemical reactions that build and maintain cells are controlled by proteins. The instructions for making proteins are found in the genes ; different genes contain instructions for different proteins or parts of proteins. Before protein is synthesized, the information in DNA must first be copied. The copy is composed of a substance similar to DNA called mRNA (for messenger RNA). It is mRNA that is used in the manufacture of protein. The diagram below illustrates that information in DNA is used to create mRNA and that information in mRNA is used to synthesize protein. The circular arrow in the diagram indicates that DNA has the ability to replicate itself. Living things reproduce Within a multicellular organism cells reproduce to enable growth and tissue repair. Individual organisms reproduce.
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