Bands in a DNA profile are similar to phenotypes because they give an indication of the individual's underlying genotype. They can be thought of as "alleles" which are inherited according to the principles of Mendelian genetics. In this system, there are two alleles: the "marker allele", which produces a band, and the "null allele" which does not. It is not possible to tell whether an individual has one or two copies of the "marker allele".

Every individual has an unique combinations of bands (or DNA profile) which he inherited from his parents. Siblings also have distinct banding patterns (DNA profiles) because they inherited different combinations of bands from their parents. Only identical twins, which share the same genetic material, have the same DNA profile. Unrelated individuals may share some bands by chance (just as not all people with brown hair are related). All bands present in a child's profile are inherited from his parents. DNA profiles can be used to establish identity or paternity.

Steps to Determine Paternity

1. Begin with the known parent. Assign the known parent a color, blue for instance.
2. Color all of the known parent's bands blue.
3. Look at the first nestling (n1). Color all of the bands from the nestling (n1) that exactly match a band from the known parent, blue.
4. Look at the remaining adult individuals. Assign each one of them a different color, green and yellow for instance.
5. Color all of an adult's band his/her assigned color.
6. Look at the nestling's remaining bands. They must have been contributed by the second parent. Compare these bands to the remaining adult individuals. Find the adult which contains ALL of the remaining non-colored bands in the nestling's profile.
7. Color the identifying bands in the nestling the same color as the second parent's bands.
8. Repeat steps #3, 6 and 7 with the remaining nestlings.

Practice

This DNA profile is from a nest of captive Harris' hawks at the Arizona-Sonora Desert Museum in Tucson, Arizona. Follow the steps described above to identify the bands in the nestlings' profile which were contributed by each parent. Use the Female (A) as the known parent.

You can now continue on to the other nests which all have three adult birds. Remember to start with the known parent.

Science Education Connection Department of Biochemistry The University of Arizona Tuesday, January 14, 1997 warder@u.arizona.edu http://biology.arizona.edu/sciconn/lessons/vuturo/ All contents copyright © 1997. All rights reserved.