1. Replication is the process used by DNA to copy itself Replication of DNA is a prerequisite to cell division, as each daughter cell must have a full copy DNA consists of 4 types of nucleotides that always bond with a single other type of nucleotide –Adenine and Thymine bond together –Guanine and Cytosine bond together REPLICATION

2. Since DNA bonds in pairs, half a strand of DNA is all that is necessary to infer what the other half of the pair should be During replication, the DNA will be unwound by a enzyme called a helicase and each strand will be matched with the appropriate nucleotide by a DNA polymerase Source: http://www.il.mahidol.ac.th/course/dna/chapter/images/editable/replication1.gif HOW REPLICATION WORKS

3. WHAT IS A DNA POLYMERASE? Enzyme that reads a single strand of DNA and matches it with complementary nucleotides in order to create a new double helix There are two DNA Polymerases used in replication – One for each strand of DNA that was split by the helicase Errors in this process result in mutation –Occurs in approximately 1 in 100 million bases –Some errors are corrected during a process called proofreading Source: http://people.smu.edu/areid/images/replicationfork.gifhttp://people.smu.edu/areid/images/replicationfork.gif Source: http://www.nehmi-ip.com.br/imagens_servicos/bio_20_p.gifhttp://www.nehmi-ip.com.br/imagens_servicos/bio_20_p.gif

4. It is not known exactly how often or which cells divide Some cells in the body do not die until the person they belong to dies, such as those in the cerebral cortex Cells in the harsher areas of the body (skin, stomach lining) turnover faster than other cells Whether there are differences in cell division occurring in adults and those occurring in children is not known REPLICATION UNKNOWNS