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Lesson Objectives At the end of this lesson you should be able to 1.Outline the four stages involved in DNA profiling 2.Define the process of DNA profiling 3.Give two applications of DNA profiling 4.Define genetic screening DNA PROFILING 1980 - American researchers discovered non-coding regions of DNA 1984 - Professor Alec Jeffries developed the process of DNA profiling 1987 - First conviction based on DNA evidence Principle of DNA Profiling All human chromosomes have sections of DNA with no known functions These sections have short base sequences These sequences repeat over and over They are inherited from parents Their length and position are unique to each person DNA PROFILING A process or technique of analysis revealing unique patterns of an individual’s DNA involving non-coding regions NON-CODING REGIONS (VNTR) STAGES INVOLVED Cells broken down to release DNA 2. DNA strands cut into fragments 3. Fragments separated 4. Pattern of fragments analysed 1. 1. DNA EXTRACTION 2. DNA CUTTING The DNA is cut up into fragments using restriction enzymes This gives lots of fragments The fragments are different sizes 3. FRAGMENT SEPARATION Samples containing the fragments are placed into individual wells in a gel using a pipette This is known as electrophoresis ELECTROPHORESIS Fragments separated by length DNA (negatively charged) Moves towards +ve terminal Shorter fragments move faster 4.DNA TRANSFER DNA is split into single strands using an alkaline solution DNA fragments transferred from gel to filter paper or nylon membrane The Gel, with filter paper attached, is removed & separated 5. ANALYSIS Radioactive probe in solution binds to DNA X-ray film Revealing a pattern of bands Applications of Genetic Screening Paternity disputes Forensic Science Genetic Screening Genetic Archaeology FORENSIC SCIENCE FAMILY RELATIONSHIPS COMMON CONCERNS Quality of sample Mistakes and inaccuracy Interpretation Privacy Evidence from criminal investigations Who should use DNA fingerprinting Cost effective Ethnic problems Genetic Screening Genetic Screening is used to : Test individuals who are at high risk of having or passing on a specific genetic disorder Screening Tests Antenatal serum screening for Down Syndrome Antenatal carrier screening for Sickle Cell Anaemia Predictive testing for hereditary cancers Predictive testing for cystic fibrosis Newborn screening for phenylketonuria, cystic fibrosis and hypothyroidism. Creating DNA Fingerprint simulation http://www.pbs.org/wgbh/nova/sheppard/lab01.html What have you learned? Can you ……………… 1.Discuss the stages involved in DNA profiling 2.Define the process of DNA profiling 3.Give two applications of DNA profiling 4.Define genetic screening End
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