Topic: The use of DNA testing in the judiciary

Target group

High school / technical school student

Core curriculum

General requirements

V. Reasoning and applying the acquired knowledge to solving biological problems. Student:

1. interpret information and explain causal relationships between processes and phenomena, formulate conclusions.

Specific requirements

VIII. Biotechnology. Basics of genetic engineering. Student:

4. Present applications of selected genetic engineering techniques in forensic medicine, forensic science, and disease diagnostics.

General aim of education

The student acquires knowledge about the use of DNA testing in the judiciary.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• explain what determines paternity and analyze the results of genetic tests;

• exchange biological traces analyzed in DNA research in the judiciary;

• describe applications of molecular methods in the judiciary;

• assess the usefulness of DNA testing in identifying victims of crime.

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers.

Lesson plan overview

Before classes

• Students get acquainted with the content of the abstract. They prepare to work on the lesson in such a way to be able to summarize the material read in their own words and solve the tasks themselves.

Introduction

• The teacher gives the topic, the goals of the lesson in a language understandable for the student, and the criteria of success.

Realization

• Participants familiarize themselves with the content presented in the interactive illustration. Then the teacher discusses the issues with the students.

• The teacher divides the class into groups and instructs the students to prepare a paper on expert tables with the use of methods based on DNA analysis in forensic science. Each expert table deals with one of the following topics:

  • analysis of biological traces found at the crime scene;

  • determining the identity of an unknown person;

  • identification of human remains.

• The leader designates a person who will discuss the topic. After completing the student's speech, the teacher initiates an open discussion on the usefulness of DNA testing in forensic science. At the end of the discussion, working on the brainstorming method, students give examples of police activities in which they would see the need or the possibility of using methods based on the analysis of genetic material.

• Students perform exercises and commands. The teacher checks and supplements the answers, providing students with the necessary information. Provides feedback..

Summary

• The teacher briefly presents the most important issues discussed in class. He answers the additional questions of the proteges and explains all their doubts. Students complete notes.

Homework

• Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

• Using the information in the abstract and available sources of information, replace the defects in establishing paternity based on blood tests.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

The use of DNA testing in the judiciary

Around 30% of men in the US who are ordered to undergo genetic testing for paternity have no common genes with the child whose father they are suspected to be. Based on this data, over one million of Americans are estimated to raise a child not of their own without knowing it. This, along with the decreasing cost of the procedure, paternity tests are becoming increasingly common, not only in the US.

The test requires taking a sample of genetic material of the child and of the suspected father. The process is usually painless; the sample is saliva with exfoliated epidermis cells, taken as a swab from the inside of the cheek. Some analytical laboratories draw blood for testing.

Currently, thanks to the Human Genome Project for the most part, several million DNA markers are known: genetic sequences that are short, unique, and very variable within a human population. The presence of such unique sequences in two persons proves they are related.

With the genetic material of the alleged father and child, their genetic profiles are created and compared. If only one or two markers are identical in both, paternity is ruled out. If all the markers of the man and of the child are the same, a statistical analysis of their frequency in the given population must be carried out, which factors into the paternity probability assessment. The biological father of the child could be a relative of the tested man, or even someone unrelated to him who has a similar set of genes, although this is a very rare occurrence.

It is possible to identify the father even before the child is born. This type of test involves amniocentesis: sampling the amniotic fluid that surrounds the fetus. The fluid contains exfoliated fetal cells which can be used to isolate DNA for paternity tests. However, due to its invasiveness, amniocentesis is not a routine procedure. DNA tests have a credibility rate of 99.9995%.

DNA tests are a common method of identifying suspects provided they leave their genetic material at the crime scene; just saliva in chewing gum or traces on a glass or a cigarette end is enough. Forensic investigators have to collect and secure a sample so as not to contaminate it with other DNA (such as their own).

Biological materials used for DNA testing in the judiciary include:

• hair,

• traces of tissue from underneath the victim’s nails (collected at the time of the abuser),

• blood,

• sweat and mucus,

• saliva,

• semen.

It is only possible to identify a person based on biological material if their data has already been entered into DNA databases, which have been built by law enforcement authorities in many countries for many years. The FBI database contains around 7 million DNA profiles, while the database of the Central Forensic Laboratory of the Police in Warsaw, around 15,000 profiles.

DNA profiles are created based on patterns with selected characteristic DNA sequences combined with markers (fluorescent labels). The sample to be identified is applied to the pattern. If both the pattern and the sample contain the same genetic material fragments, they complement each other, and the marker emits light. The result is observed under a fluorescence microscope and recorded as a graph.

DNA tests are standard procedure when an unidentified person or a dead body is found, especially if fingerprints cannot be taken or there is no record of the given person’s fingerprints in available databases. From among missing persons, those of the same gender and age are selected, and biological material, e.g. from a comb or a tissue used by this person, is acquired from their family. By examining the DNA from the unidentified person and DNA provided by the missing person’s family, laboratory workers can confirm or deny the identity of this person.

Other applications of genetic tests include the identification of victims from mass graves or disasters, or victims of accidents such as mining disasters. Genetic testing are also used to identify several dozen or even several hundred years old remains. Genetic material is isolated from the bone and compared with the DNA of living relatives. This is the method of examining the degree of kinship of people buried in family graves.

• Genetic tests for paternity have a 99.9995% reliability rate.

• Genetic testing is useful for determining paternity and for identifying crime suspects, missing persons, and dead bodies.