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Fax: 571-312-0544

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Charlotte Lozier Institute

Phone: 202-223-8073
Fax: 571-312-0544

2776 S. Arlington Mill Dr.
#803
Arlington, VA 22206

The
Voyage of Life

DNA Replication

Dive Deeper

DNA stores a staggering amount of information in its structure. This remarkable molecule resembles a twisted ladder, called a double helix. Each rung of the ladder consists of a pair of molecules called a base pair. Each molecule in the base pair has one correctly matching molecule. Humans have about 3 billion base pairs of DNA inside their 46 chromosomes.1 If we could unwind and stretch out the DNA of a single cell, it would measure about one meter, or 3 feet long.2

DNA replication. DNA is composed of two strands twisted into a double helix. Before replication the strands separate from each other. Each strand then acts as a template for the formation of a new DNA molecule. DNA contains sections called genes, which encode the body's genetic information. (Image Credit: Science Source)

Every time that a cell divides, it makes a complete copy of its DNA. To replicate the DNA, the rungs of the ladder actually come apart, and each open rung gets a new matching molecule. Cells divide many times before they reach their final destination. For example, an adult human skin cell is the result of 8,000 cell divisions since conception.3 Any mistake in replication could cause a permanent change in the DNA, called a mutation. Therefore, cells have many mechanisms to prevent copying mistakes.4

DNA replication also occurs remarkably fast. To replicate the entire set of genes within a few hours, DNA replicates at 208,000 base-pairs per second.5 DNA gets copied at thousands of sites on the chromosomes simultaneously to proceed with this stunning speed and accuracy.6

Back to The Voyage of Life
Sources
  1. Sadler, Thomas W. Medical Embyrology. 14th ed., 2019.
  2. EHD: Appendix, “Appendix | Prenatal Overview,” accessed April 3, 2020, https://www.ehd.org/dev_article_appendix.php#fb16.
  3. Brandon Milholland et al., “Differences between Germline and Somatic Mutation Rates in Humans and Mice,” Nature Communications 8, no. 1 (May 9, 2017): 1–8, https://doi.org/10.1038/ncomms15183.
  4. Donald F. Conrad et al., “Variation in Genome-Wide Mutation Rates within and between Human Families,” Nature Genetics 43, no. 7 (June 12, 2011): 712–14, https://doi.org/10.1038/ng.862.
  5. EHD: Appendix, “Appendix | Prenatal Overview,” accessed April 3, 2020, https://www.ehd.org/dev_article_appendix.php#fb16.
  6. Bruce Alberts et al., “The Initiation and Completion of DNA Replication in Chromosomes,” Molecular Biology of the Cell. 4th Edition, 2002, https://www.ncbi.nlm.nih.gov/books/NBK26826/.
See Full Bibliography

All images and illustrations on The Voyage of Life were reviewed by credentialed scientists for accuracy.

Medical art animation was used to provide a schematic representation of fetal development, with some features, including timing, not to scale. The animation was chosen as an ethically uncompromised guide to fetal development. There are many real human images at each developmental age showing the most accurate fetal forms throughout development. A concerted effort was made to use images and material in which the human embryo or fetus did not undergo any known harm.

Page last updated on October 21, 2022
Sperm-egg fusion