jimtrue.com : school : CJT2260 : 2003-10-30: DNA Study Session
Posted by Jim True on October 30, 2003 6:54 AM. Last Updated October 22, 2006 9:23 PM
Disclaimer for all material noted here is at the bottom of this web page.
DNA Interactive Website (http://www.dnai.org)
Timeline - 1920's onwards - Fredrich Miescher (What molecule did he discover?) Miescher went further than Mendel and isolated a substance called "nuclein". He determined that nuclein was made up of hydrogen, oxygen, nitrogen (used bandages, full of pus and white blood cells).
DNA - deoxyriobnucleic acid - phosphates, sugar, 4-Bases (A,T,G,C) AT & GC, billions of base pairs long. Most of the sequencing in DNA is pretty common for all animals (eyes, ears, heads, etc.) and a smaller fraction will code for specific characteristics for a species. Humans & Chimps share about 99% of our DNA Sequence. 2/28/1953 james Watson saw the structure of DNA
Hydrogen bonds that stick off from the base pairs; C and G bond is less likely to break. A and T are more likely to break (double bonds).
Between individuals, 0.10 difference in our DNA.
What is the structure of DNA (Code - DNA/Interactive);
Packaging
RFLP - Restriction Fragment Length Polymorphisms.
PCR - Polymerase Chain Reactions
Good DNA, pristine sample. Very long DNa strands. High Molecular Wt. Quality. This is what you will use to do RFLP (you will need a lot), a stain about the size of a quarter. Need a lot of genetic material for RFLP and it needs to be in pristine condition.
PCR, allows you to do a lot more with a little bit of sample. Sample the size of a pinhead, and broken down. PCR AMPLIFIES DNA. Amplication, making copies or increasing the number of copies, increase the amount in the sample). Can make as much as you want so you can run more tests.
Exponential process ("you tell two friends, and they tell two friends and so on, and so on") 2, to 4, to 8, to 16, to 32. PCR process takes hours, RFLP can take weeks to process.
RFLP developed by whom and what year? Sir Alec Jeffreys, 1985.
PCR, developed by Kary Mullis, 1991 (Nobel Prize in 1993) (brainstorm driving along the road in his convertible and rushed back to his lab.
PCR greatest benefit to investigators because it can work with small amounts of evidence and very quick amplification. Biggest drawback, contamination will create numerous copies of 'garbage'.
mtDNA - Mitochondrial DNA analysis. Powerhouse of the cell. Much more mitochondrial DNA in a cell than nuclear DNA. Only shows maternal lineage. It is believed that when mitochondria were first formed they did not share DNA; they had a symbiotic relationship with the DNA in the host cell.
DNA, inherited from Mom and Dad
mtDNA, inherited from Mother only. Siblings cannot be distinguished from each other.
mtDNA is also heartier. Bones, Teeth, hair shaft.
Recombinant DNA: recombining DNA to get a specific effect or characteristic that you want. Corn plants, a whole field of them. Some doofus has let in corn feeding beetles. The corn feeding beetles have spread throughout the USA. Need to make the corn more resistant to the beetles.
http://www.bio.umass.edu/biochem/mydna/modules/charge.html
(Electrophoresis module)
Plate with an agar gel; battery connected to it. Increase or decrease the concentration of the agar gel. DNA in the agar gel. Longer pieces are heavier, smaller ones will move more quickly.
Once the pieces are moved through the electrophoretic gels, they are dyed, and will show up as bands within the gel. Smaller pieces to the anode and larger pieces towards the cathode (they cannot move as quickly through the gel).
The STR pattern will change based on the agarose solution, the current applied and the number of lengths that the DNA is cut into.
AutoRads - Control lanes, some known samples, and some unknown samples. Lanes will stay to themselves, they will not overlay.
mRNA - Messenger RNA, Uracil replaces the Thymine in the strand. So A-U, T-A, C-G, G-C.
"Central Dogma"
Forgo the Legal issues; show more on collection techniques.
http://science.howstuffworks.com/dna-evidence.htm (Matching DNA and Creating a DNA Profile: The Basics).
Disclaimer: These are MY notes taken from classroom lectures while I'm in the classroom. While I'm perfectly happy to share my notes with my classmates and I know I take very good notes, you should still make every effort to attend the class and TAKE YOUR OWN NOTES. I will not transcribe everything the instructor says in the classroom, and I will NEVER post pre-exam reviews. My notes will not replace the value of actually attending class and taking your own class notes.I also cannot attest to their accuracy, other than they are what was provided in the lecture; you should not reference my notes as "expert opionion" by any means, and if you notice an error or omission, please do me the favor of e-mailing me with the correction and I will re-post my notes. End of Disclaimer.