Chapter 12 DNA Analysis

1. Chapter 12 DNA Analysis

2. Identify individuals from unique genetic code • In every nucleated cell in the human body • Can be extracted from blood, semen, urine, bone, hair follicles, and saliva

3. In the nucleus of each cell are 46 chromosomes. Each chromosome is made of long strands of DNA wrapped around proteins called histones.

4. You have 23 pairs of chromosomes One copy is from each parent.

5. A gene is A segment of dna that contains the instruction s to make a protein There are about 20,000-25,000 genes in the human genome. Most of your DNA (98%) does not code for proteins.

6. DNA structure Deoxyribonucleic Acid is a macromolecule containing the sugar deoxyribose. It is a polymer made of two strands of repeating units called nucleotides. Each nucleotide is made of three parts…a sugar, a phosphate group, and a nitrogenous base. There are only four different nitrogenous bases… Adenine Thymine Cytosine Guanine

8. Hair color Skin color freckles Widows peak gene Eye color Gene; a segment of DNA that codes for a particular protein

9. One strand of nucleotides

10. The hydrogen bonds are very weak, so the two strands can “unzip” allowing the base sequence to be “read” when the DNA copies itself, or when the gene’s instructions are used to create proteins.

11. Every three bases codes for one amino acid. A long string of amino acids make up a protein, and our proteins that we make give us our traits.

12. Jack the Ripper The order of the 3 billion base pairs is 99.9% identical in all humans. The unique 0.1% gives us incredible diversity. Einstein Mozart You!

13. Types of DNA Nuclear found in the nucleus constitutes 23 pairs of chromosomes inherited from both parents each cell contains only one nuclei Mitochondrial found in the cytoplasm is inherited only from mother each cell contains hundreds to thousands of mitochondria can be found in skeletal remains

14. Nuclear DNA is present in the head of the sperm. Mitochondrial DNA is present in the tail. At conception, the head of the sperm enters the egg and unites with the nucleus. The tail falls off, losing the father’s mitochondrial DNA.

17. Typically blood and other bodily fluids provide DNA for forensic testing and determining a DNA profile, or fingerprint. Uses of DNA Fingerprinting: Identify potential suspects Clear the wrongly accused Identify Crime and Catastrophe victims Establish paternity Match organ donors and recipients

18. RFLP Analysis Restriction Fragment Length Polymorphism 1. After isolating the DNA from the cell, restriction enzymes are used to “chop up” the DNA into small pieces (or DNA “fragments”). Different restriction enzymes recognize different DNA sequences and therefore cut the DNA at different places in the sequence. You end up with many fragments of different lengths (they’re polymorphic).

19. Animation

21. 2. Now, the many fragments are separated by gel electrophoresis. A gel provides a barrier through which the DNA fragments can slowly travel. An electrical current draws the negatively charged DNA from one end of the gel to the other, but the polymorphic fragments don’t travel at the same speed, so they’re separated by size and charge. Virtual lab Animation

24. Unique banding pattern is your DNA profile or DNA fingerprint

25. Polymerase Chain Reaction (PCR) • Make millions of copies of DNA from a small sample • Quick and easy in the lab, DNA less susceptible to degradation • Requires 50x less DNA than what is needed for RFLP • Contaminant DNA will be amplified as well

28. Short Tandem Repeats (STR) • Used more commonly than RFLP because: • Takes less time • Requires less of a sample size • Is more exclusionary (eliminates more people as the source of the DNA)

29. STR’s are locations (loci) on the chromosome that contain short sequences of 2 to 5 bases that repeat themselves in the DNA molecule. They are “markers” not found in the “coding” part of a gene.

30. THO1 One commonly used STR 5 – 11 repeats of A-A-T-G on chromosome 11 in the introns of the tyrosine hydroxylase gene There are 7 variants of THO1 in humans

31. Short Tandem Repeats (STR) • STR typing is visualized by peaks shown on a graph. • Each peak represents the size of the DNA fragment.

32. FBI’s CODIS DNA Database • Combined DNA Index System • Used for linking serial crimes and unsolved cases with repeat offenders • Launched October 1998 • Links all 50 states • Requires >4 RFLP markers and/or 13 core STR markers

33. CODIS

34. CODIS

35. 1. Probability of Identity Is a measure of the likelihood that 2 random individuals will have an identical STR type

36. 2. Probability is determined By multiplying their frequencies

37. 3. Probability ofanother unrelated individual Having the first 3 STRs match is 1 in 5000 STRAfrican-AmericanU.S Caucasian D3S1358 0.097 0.080 vWA 0.074 0.068 FGA 0.036 0.041 8/100 x 6.8/100 x 4.1/100 = 223 / 1 000 000 ≈ 1 / 5000in the U.S. Caucasian population

38. 4. The probability of frequency For the first 6 STRs is 1 in 2 million

39. The probability of frequency of all 13 STRsis 1 in trillions (1 trillion= 1 000 000 000 000)

40. World population is over 7 billion!

41. Three Possible Outcomes • Match—The DNA profile appears the same. Lab will determine the frequency. • Exclusion—The genotype comparison shows profile differences that can only be explained by the two samples originating from different sources. • Inconclusive—The data does not support a conclusion as to whether the profiles match.

42. DNA Interactive The website below has a STR animation demonstration. Click on human identification, profiling and then on the third circle called Today’s DNA Profiling to see the demonstration. http://www.dnai.org/d/index.html

43. Nicole Brown Simpson’s blood a match for the blood on a piece of evidence. Data

44. Uses of DNA Fingerprinting A. Identification of remains

45. Case Study: The Angel of Death: Josef Mengele

46. Josef Mengele was a Nazi war criminal notorious for grotesque human experiments that he carried out at the Auschwitz concentration camp.

47. After the Second World War he fled from the Allies and escaped to South America. The fugitive succeeded in living out the rest of his days without being caught.

48. Wolfgang Gerhard Died 1979 • 1985 Embu

49. Using DNA extracted from blood provided by Mengele’s ex-wife and son, it was concluded that it was more than 99.94% certain that the skeleton was Mengele’s Irene Rolf

50. B. Paternity Cases Who’s your daddy?