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DNA is passed along through the process of inheritance—the passing of traits from parents to offspring via genes.
Because we’re of the same species, all humans have the same genes. But what makes each human an individual is that the instructions coded on these genes differ slightly from person to person. In other words, the sequence of bases within a gene may be slightly different. How does this happen? Let’s take a look…
DNA and Chromosomes
Thousands of genes can be found on a single strand of DNA, and most organisms have more than one strand. Humans, for example, have 46.
During reproduction, each strand of DNA compacts and coils into a chromosome. The chromosome copies itself to pass on genetic information to a new generation.
 DNA and Genetic Variation
The copying of chromosomes, called replication, is long and complicated, so it isn’t surprising that mistakes in the genetic sequence can occur. These mistakes—called mutations—can alter genes and create new traits, such as variations in the shape of a mollusk’s shell or the color of person’s eyes.
These traits are then passed on in the DNA to the next generation. Over many generations and through evolution, changes in DNA can accumulate in new species.
So, diversity on our planet is caused by DNA, but species are also related through DNA.
Continue to Why Do We Study DNA? >>
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