DNA

The subunits that comprise DNA are called nucleotides. A nucleotide contains the following three parts:

• a five-carbon sugar molecule called deoxyribose
• a phosphate group
• a nitrogenous (nitrogen-containing) base

The nitrogenous base within a nucleotide may be one of the four possible kinds:

• Adenine
• Thymine
• Cytosine
• Guanine

DNA molecules are comprised of combinations of these base pairs.

For another view of a DNA molecule, follow this link: DNA

This link will take you to a slide show on the process of gel electrophoresis. Electrophoresis is the movement of a charged molecule in an electrical field. Gel electrophoresis separates molecules of different lengths. DNA isolated from viruses, bacteria and other organisms may be analyzed for purity, molecular size, and configuration (e.g. linear, circular) by the technique of agarose gel electrophoresis.

Human female

Drosophila polytene

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