The following sites provide you with tutorials, information-gathering opportunities, and/or interactive exercises focusing on the concepts covered in each chapter.

• Eukaryotic Gene Expression from The Biology Project will help you learn about gene expression.

• A Science Odyssey: You Try It from PBS Online has an interactive activity on DNA replication and gene expression.

• MIT Biology Hypertextbook: Review the genetic code and transcription by studying this chapter of the MIT Biology Hypertextbook.

• Visit the Genetic Code Viewer to examine the genetic codes of a variety of organisms.

• Online Mendelian Inheritance in Man is a searchable database of information on genetic diseases. Try searching for information about rickets.

• The National Center for Biotechnology Information site provides you with the tools needed for "data mining" on the web. At this site, you can compare gene and protein sequences using BLAST, explore the outline of the complete human genome sequence using GeneMap'99, compare DNA from human and mouse sources using Human-Mouse Homology Maps, and obtain human, rat, and mouse gene sequence information using LocusLink. Other resources are also available at this site, so don't be afraid to explore!