Powerpoint to help with P6

1. Powerpoint to help with P6 P6: Outline biological techniques

2. Fingerprints • Uses of fingerprints: They can be used identify who was present at a crime scene. • How it works: You match up fingerprints that have been recovered at a crime scene to fingerprints of suspects. • There are three main types of fingerprints but each person has a unique fingerprint (including twins). The lines in finger prints have gaps known as ridges, and it is where these ridges are placed that are unique to individuals

3. Fingerprints

4. Fingerprints • Composite fingerprints:any combination of two or morefingerprint patterns or unusual patterns that do not fit in any other group are known as composite fingerprints and are sometimes categorized asaccidental whorls.

5. Blood groups

6. Blood groups • USES OF Blood group analysis: It can be used to confirm the group type of a person that may have been involved with a crime • HOW IT WORKS: To carry out the test, different antibodies are added to the blood samples. Antigen A will react with Anti-body A and Antigen B will react with Anti-body B.

7. Blood groups

8. Analysing bones • The use of analyzing bones and skeletons is often to identify bone fragments and teeth and identify victims from scenes of mass disasters and war graves • How it works: You can use the proportions of the bones to estimate the age, gender and even ethnicity of the dead body

9. Analysing bones

10. Hair and fibre for identification • Head hairs are shed by individuals each day onto clothing and items in their environment. This evidence may be transferred during physical contact between victims and suspects or in crime scenes. • If the living root is attached the hair then the hair can be analysed for DNA. • The ends of the hair can be analysed to indicate if the hair has been shed naturally or ripped out in a violent attack.

11. Hair and fibre identification • The use of analysing hair/fibres is mainly to place suspects at a scene of a crime. Also if the living root is in the hair sample then this sample will contain DNA that can be analysed. • How it works: Hair/fibre samples are analysed under the microscopes and then visually confirmed if there are matches between suspects/victims and samples found at a crime scene.

12. DNA sequencing and genetic fingerprints • All living cells with a nucleus contain DNA which can be analysed and used to determine the identity of a sample found at a crime scene. • With the exception of twins, every individual’s DNA is unique

13. DNA sequencing and genetic fingerprints • Uses: this techniques is used to link suspects to crime scenes by matching up DNA of suspects to biological tissue found at a crime scene • How it works: DNA in a biological tissue found at a crime scene is broken up into fragments to produce a genetic fingerprint. The genetic fingerprint is then analysed to see if it matches up to the genetic fingerprints of suspects

14. An example of genetic fingerprint

15. DNA profiling • This is an example of a technique used to produce genetic fingerprints from DNA samples • How it works: uses an electrical current to separate out the nucleotides that make up the DNA

16. Main stages of DNA profiling • DNA Extraction: DNA is separated and removed from the sample of biological evidence • DNA Digestion: DNA molecules are broken up • DNA separation: DNA fragments are separated out using electrophoresis • DNA visualisation: To make the separated strands of DNA visible • DNA analysis: Comparing the sample from crime scene to known samples of the suspects