1 / 41

DNA Analysis

DNA Analysis. Lesson 1 – Biology of DNA. Lesson Essential Question: What are the biological aspects of DNA?. Vocabulary: Chromosomes, DNA, genes, proteins, hydrogen bonds, helix, amino acids. 1953—James Watson and Francis Crick discover the configuration of the DNA molecule

alma
Download Presentation

DNA Analysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. DNA Analysis

  2. Lesson 1 – Biology of DNA • Lesson Essential Question: • What are the biological aspects of DNA? • Vocabulary: • Chromosomes, DNA, genes, proteins, hydrogen bonds, helix, amino acids

  3. 1953—James Watson and Francis Crick discover the configuration of the DNA molecule 1980—Ray White describes first polymorphic RFLP marker 1985—Alec Jeffreys isolates DNA markers and calls them DNA fingerprints 1985—Kary Mullis develops PCR testing 1988—FBI starts DNA casework 1991—first STR paper 1998—FBI launches CODIS database Historical Information

  4. Cell Where can DNA be found? Cell Types Blood Hair Roots Saliva SAME Sweat Semen Various Tissue

  5. Types of objects where DNA may be found • Blood Stains • Chewing Gum • Stamps & Envelopes • Saliva • Sweaty Clothing • Bone • Hair • Fingernail Scrapings

  6. Nucleus Where is DNA in the body? Cell

  7. Cell Where types of DNA are found in a cell? Mitochondrial DNA Nuclear DNA

  8. Nucleus Paternal Chromosome Maternal Chromosome Where is DNA in the body?

  9. Chromosome DNA Where is DNA in the body?

  10. DNA Structure Deoxyribonucleic acid. A macromolecule composed of two strands of monomers called nucleotides. These strands are joined in the middle by hydrogen bonds. The strands twist around one another forming a double helix. http://cancergenome.nih.gov/media/DNAKit_illustration_image.jpg

  11. Nucleotide Structure 5-C sugar – deoxyribose Phosphate group Nitrogen containing base -4 of two types Adenine Guanine Cytosine Thymine http://www.msu.edu/course/isb/202/ebertmay/drivers/nucleotide.jpg

  12. Double Helix A T C G Units A =Adenine T =Thymine G =Guanine C =Cytosine

  13. Pyrimidines – have one ring in their structure Thymine Cytosine Purines – have two rings in their structure Adenine Guanine http://student.ccbcmd.edu/~gkaiser/biotutorials/dna/images/DNAbases.jpg

  14. Nitrogen Base Pairing Bases pair in a specific pattern. A purine always bonds to a pyrimidine Adenine bonds to thymine. Guanine bonds to cytosine.

  15. The bases are held together by weak hydrogen bonds.  The sides of the DNA ladder are composed of alternating sugar and phosphate and are called “backbones”.

  16. Lesson 2 – DNA Testing • Lesson Essential Questions • What types of tests are available to test for DNA? • What are the forensic uses of DNA? Vocabulary: Enzymes, DNA extraction, restriction enzymes, RFLP Analysis, electrophoresis, probe, electrophoresis, polymerase chain reaction (PCR), alleles, short tandem repeats (STR), DNA fingerprinting

  17. DNA typing is a method in which DNA is converted into a series of bands that ultimately distinguish each individual. Only one-tenth of a single percent of DNA (about three million bases) differs from one person to the next. Scientists use these regions to generate a DNA profile of an individual. Three percent of the human DNA sequences code for proteins. Ninety-seven percent is non-coding and is repetitive, repeating the same sequence over and over. DNA Typing

  18. RFLP—restriction fragment length polymorphism PCR—polymerase chain reaction STR—short tandem repeats DNA Typing – 3 Ways to To Look at DNA“Fingerprinting”

  19. Restriction enzymes are used to cut DNA into smaller fragments that can then be separated and characterized for identification. Isolate—separate DNA from the cell Cut—use of restriction enzymes to make shorter base strands Sort—by size using electrophoresis Analyze—the specific alleles for identification RFLP—Restriction Fragment Length Polymorphisms

  20. PCR is a technique used for making copies of a defined segment of a DNA molecule. This can be valuable when the amount of evidence is minimal. Millions of copies of DNA can be made from a single speck of blood. PCR—Polymerase Chain Reaction

  21. 1. Heat the DNA strands, causing the strands to separate (unzip). 2. Cool the mixture and add a primer, a short sequence of base pairs that will add to its complementary sequence on the DNA strand. 3. Finally, add a DNA polymerase and a mixture of free nucleotides to the separated strands. Heat again to around 75°C for the completion. After Procedure: The outcome is a doubling of the number of DNA strands. Heating, cooling, and strand rebuilding is repeated typically 25 to 30 times, yielding more than one million copies of the original DNA molecule. Each cycle takes less than two minutes from start to finish. PCR—Polymerase Chain Reaction Procedure

  22. Minute amounts of DNA may be used for amplification. Small fragments of DNA can be used. Contaminant DNA, such as from fungal and bacterial sources, will not amplify because human-specific primers are used. However, human contamination can be a problem. Advantages of PCR

  23. A technique used to separate DNA fragments An electrical current is moved through a gel substance, causing molecules to sort by size. The smaller, lighter molecules will move the farthest on the gel. After developing, the fragments can be visualized for characterization. Electrophoresis

  24. Electrophoresis, continued Pipette the DNA.

  25. Electrophoresis, continued Load DNA into the gel wells.

  26. Electrophoresis, continued Run the gel. Observe and compare bands of DNA.

  27. STR is another method of DNA typing. STRs are locations (loci) on the chromosome that contain short sequences of two to five bases that repeat themselves in the DNA molecule. The advantages of this method are that it provides greater discrimination, it requires less time and a smaller sample size, and the DNA is less susceptible to degradation. Short Tandem Repeats (STR)

  28. Extract the gene TH01 from the sample. (TH01 has seven human variants with a repeating sequence of A-A-T-G.) Amplify the sample by means of PCR. Separate by electrophoresis. Examine the distance the STR migrates to determine the number of times TH01 repeats. After Procedure: Each person has two STR types for TH01—one inherited from each parent. By continuing the process with additional STRs from other genes, you can narrow down the probability of DNA belonging to only one person. STR typing is visualized by peaks shown on a graph. Each represents the size of the DNA fragment. The possible alleles are numbered for each locus. Short Tandem Repeats (STR) Procedure

  29. DNA Analysis STR Example 28

  30. Click on Human Identification, Profiling, and then on the third circle called Today’s DNA Profiling to see the demonstration. STR animation DNA Interactive

  31. 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 do not support a conclusion as to whether the profiles match.

  32. Found in the nucleus Constitutes 23 pairs of chromosomes inherited from both parents Each cell contains only one nucleus Found in the cytoplasm Is inherited only from mother Each cell contains hundreds to thousands of mitochondria Can be found in skeletal remains Types of DNA Nuclear Mitochondrial 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.

  33. Analysis of mDNA is more: Rigorous Time-consuming Costly than nucleic testing of DNA mDNA is constructed in a circle or loop Thirty-seven genes are involved in mitochondrial energy generation Is used when nuclear DNA typing is not possible Mitochondrial DNA

  34. Summary of DNA Analysis

  35. To identify potential suspects To exonerate individuals To identify crime and casualty victims To establish paternity To match organ donors Uses of DNA Profiling

  36. Lesson 3 – Case Studies of DNA • Lesson Essential Question • What are some of the cases that have been solved using DNA? • What are the ethical issues involving using DNA to solve crimes? • Vocabulary: CODIS

  37. 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 FBI’s CODIS DNA Database Combined DNA Index System

  38. Greater automation of the DNA typing process Use of SNPs—single nucleotide polymorphism, which measures a one-nucleotide change or difference from one individual to another. More sites are needed to differentiate between individuals (30 to 50 SNPs to attain the frequencies of the 13 STR loci), but it can be done with robots and automation. The Future

  39. Important Case Studies • Green River Killer Case • Innocence Project • Search for other high profile cases that DNA has played a large role in. For additional information about DNA and some famous cases, check out truTV’s Crime Library at: www.crimelibrary.com/criminal_mind/forensics/dna/1.html

  40. DNA Fingerprinting Project

More Related