DNA 101: Review of DNA Structure and Function PDF

DNA 101: Review of DNA Structure and Function The Structure of DNA 3 back-to-back articles published in Nature in April 1953 define DNA as a double helix 1. Francis Crick and James Watson 2. 2. Rosalind Franklin (Photo 51) 3. 3. Maurice Wilkins Linus Pauling The Playe...

DNA 101: Review of DNA Structure and Function The Structure of DNA 3 back-to-back articles published in Nature in April 1953 define DNA as a double helix 1. Francis Crick and James Watson 2. 2. Rosalind Franklin (Photo 51) 3. 3. Maurice Wilkins Linus Pauling The Players 1952 - Rosalind Franklin photographs crystallized DNA fibers 1953 - James Watson and Francis Crick predict the double helix structure of DNA 1977 - Frederick Sanger develops DNA sequencing Definition of DNA DNA = Deoxyribonucleic Acid Found in all living cells; controls inheritance Contains genetic material ○ Nucleotides ○ Adenine ○ Thymine ○ Guanine ○ Cytosine Robust structure: helical coil, protects inner rungs of the ladder Nucleotides A pairs with T G pairs with C Van der Walls forces ○ Find each other ○ Stay connected, gently Picture of DNA Inside is important The sequence makes up a gene Chromosomes Contain DNA The cell must divide correctly DNA must replicate correctly Failures can lead to ○ Death ○ Disease ○ Cancer ○ Malfunction Karyotype: ○ 22 Autosomes ○ 1 pair of Sex Chromosomes Trisomy Syndromes ○ Downs (21) ○ Edwards (18) ○ Patau (13) Cell Division Mitosis ○ Cell duplicates itself ○ New cell is identical to its parent cell ○ Repair and growth Meiosis ○ Cell divides for reproduction ○ One cell results in 4 daughter cells ○ Gametes (sperm, egg) DNA is First Used in Law Enforcement 1984 Sir Alec Jeffreys: RFLP DNA Fingerprinting 1985 DNA Fingerprinting used in an immigration case STRs Vs. SNPs The New Step is Genetic Genealogy STRs in CODIS SNPS IN DTC Databases DNA evidence DNA evidence DNA extraction DNA extraction STR analysis SNP analysis Upload to CODIS Upload to GEDmatch/FTDNA Genetic Genealogy CODIS first, then Genetic Genealogy Indexes ○ Convicted Offender ○ Arrestee ○ Missing Person ○ Unidentified Human Remains ○ Offender Index Start With CODIS CODIS contains over ○ 14,492,991 offender profiles ○ 4,305,472 arrestee profiles ○ 1,096,398 forensic profiles Per federal guidelines: ○ Profile into CODIS, if no hit then ○ Profile into GEDmatch/FTDNA/DNAJustice ○ Person of interest (POI) developed ○ Obtain DNA of POI ○ Compare POI’s STR profile to physical evidence How Does Genetic Genealogy 4 Steps to Genetic Genealogy Find: ○ Choose the best DNA matches Create:  ○ Create a family tree for each Group: ○ Determine how the trees fit together ID: ○ Determine how your DNA fits in DNA Segment Triangulation If 2 people match a 3rd person on the same segment AND They all match each other THEN They all descend from the same ancestor Finding the parents of an adoptee requires the use of DNA Segment Triangulation The Niskayuna Arrest of Stephen Smerk In 1994, 37-year-old Robin Lawrence was murdered in her home in Fairfax Virginia; the case went cold until recent developments in DNA technology. Parabon Labs used DNA from the suspect to make a composite image of his face and to identify his relatives resulting in the identification of Stephen Smerk, a local of Niskayuna. Case 1: NorCal Rapist - Roy Waller 10+ rapes and kidnappings ▪ 1991–2006 in six Northern California counties ▪ Close DNA match—no family trees ▪ Solved in 45 minutes Estimated Time to Solve a Case per cM Matches* 3500 cM → This is a parent → Hours 2500 cM → This is his sibling → Hours 900 cM → This is his 1st cousin → Days 300 cM → This is his 2nd cousin → Weeks