* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download DNA
Survey
Document related concepts
Eukaryotic DNA replication wikipedia , lookup
Zinc finger nuclease wikipedia , lookup
DNA repair protein XRCC4 wikipedia , lookup
DNA sequencing wikipedia , lookup
Homologous recombination wikipedia , lookup
DNA replication wikipedia , lookup
DNA nanotechnology wikipedia , lookup
DNA polymerase wikipedia , lookup
DNA profiling wikipedia , lookup
Microsatellite wikipedia , lookup
Transcript
Chapter 13 DNA - Deoxyribonucleic Acid Discovered in 1868 – at that time is was not understood what it was or why it was there Major breakthrough was made in the 1950’s - (won a Nobel Peace Prize) by James Watson and Francis Crick In 1985, Alec Jeffreys discovered that portions are like a fingerprint (VNTR – variable number of tandem repeats) he used RFLP Gene Fundamental unit of heredity Instructs body cells from hair color to susceptibility to diseases DNA continued… Is a polymer linked together by nucleotides A – Adenine C – Cytosine G – Guanine T – Thymine Base pairing A pairs with T, G pairs with C 100 million base pairs DNA at work Proteins – made up of amino acids (aa’s) polymers that play a basic role in the structure and function of living things. Amino acids (aa’s) - are building blocks There are 20 known aa’s Forensic DNA Testing Scientists first used: RFLP – Restriction Fragment Length Polymorphism Quarter sized sample needed for testing RFLP DNA typing has the distinction of being the first scientifically accepted protocol in the US used for the Forensic characterization of DNA. Replication of DNA PCR – Polymerase Chain Reaction (Rxn) Technique for replicating/copying a portion of a DNA strand outside a living cell. Sample size no longer a limitation – pin size could be used Is a more viable DNA typing technique, offers increased sensitivity. Restriction Enzymes (NZM or NZYM) Chemicals that act like scissors to cut DNA molecules at specific locations DNA replication continued… STR – Short Tandem Repeats Are locations (loci) on the chromosomes that contain short sequence elements that repeat themselves within the DNA molecule throughout the human genome. IMPORTANT – repeating sequence is short in length – 3-7 bases – entire strand is fewer than 400 bases in length. Much shorter than the strands used for RFLP Much less susceptible to degradation or may often be recovered from bodies/stains that have been subjective to extreme decomposition. Types of DNA Gel Electrophoresis – gel plate, buffer and electric charge is used to “move” proteins – by hand/see Capillary electrophoresis – preferred, easier – by computer (use 13 core loci for CODIS) Types of DNA Nuclear DNA – tells mother – father Commonly used, less expensive Mitochondrial DNA – tells mother – child Analysis is more sensitive than nuclear DNA profiling More rigorous and time consuming and more expensive vs nuclear DNA DNA and Trials General Acceptance came from paternity cases (techniques and terminology became more known to judges and juries alike) 1987 – Tommie Lee Andrews - First person in US convicted of a crime base on DNA evidence OJ Simpson Trial made it nationally known DNA evidence has exonerated people wrongly convicted and imprisoned for a crime DNA at a Crime Scene “It’s like leaving your name, address, and social security number at the scene of the crime.” 1998 – FBI lauches CODIS – Combined DNA Index System Offender - individuals Forensic – cases with DNA evidence