1. DNA and the Language of Life Chapter 12

2. How did scientists learned that DNA is the genetic material?

3. Genes are Made of DNA  Griffin’s experiment (1928)  Avery’s experiment (1944)  Hershey and Chase experiment (1952)

4. Griffith’s experiment - 1928

5.  Griffith showed that although a deadly strain of bacteria could be made harmless by heating it, some factor in that strain is still able to change other harmless bacteria into deadly ones. He called this the "transforming factor."

6. Avery’s experiment - 1944  Transforming factor - Protein or DNA? Avery and colleagues treated a mixture of heat- treated deadly strain and harmless strain of bacteria with:  Protein-destroying enzyme  DNA-destroying enzyme

7. Hershey and Chase experiment -1952

8.  The basic unit of the DNA molecule is called: NUCLEOTIDE

9. A NUCLEOTIDE in DNA has three parts:  A ring-shaped sugar called deoxyribose  A phosphate group  A nitrogenous base (single or double ring of carbon and nitrogen atoms)

10. Nucleotide monomers join together by covalent bonds between the sugar of one nucleotide and the phosphate of the next, forming a sugar- phosphate backbone.

11. Nitrogenous Bases

12. The bases pair up (A-T & G-C) forming the DOUBLE HELIX first described by Watson and Crick

13. Watson, Crick and Franklin

14. Various ways to model DNA structure http://www.umass.edu/molvis/tutorials/dna/dnapairs.htm manipulate DNAhttp://www.umass.edu/molvis/tutorials/dna/dnapairs.htm

15. Why does DNA need to be replicated? Growth – new cells - reproduction How does this process happens?

16. REPLICATION IN 3 STEPS  DNA replication results in two new strands, each containing one new strand (yellow) and one original strand (blue)

17.  Weak bonds  Hydrogen bonds  Comes apart easily  Comes together easily

18. Overview of DNA replication  DNA separates  Complementary nucleotides are linked along separated strands

19. initiate  Initiator protein guides unzipper protein (helicase) to correct position on DNA

20. untwister  Untwister (topoisomerase) unwinds the DNA double helix in advance of the unzipper

21. Unzipper separates DNA strands, breaking weak bonds between the nucleotides unzip

22. assemble Builders (polymerases) assemble new DNA strand by joining nucleotides to their matching complements on the exposed strands

23. straightners  Straighteners (single-strand DNA binding proteins) keep single strand of DNA from tangling

24. Phosphate provides energy Phosphate bond energy from the new nucleotides is used to make the new bonds

25. Leading vs. Lagging strand  Leading (top) strand is built continuously as the builder follows behind the unzipper, but the Lagging (lower) strand builds in the opposite direction

26. Lagging strand  Lagging (lower) builder makes a loop with the DNA strand and builds in opposite direction

27. Lagging strand  Built in small sections  Sections linked by enzyme ligase

28. Repairs of DNA  Erasers (Repair Nuclease): find poorly matched or damaged nucleotides and cut them out

29. Repairs of DNA  Builders (Polymerase): fill gaps using other DNA strand as a guide

30. Repairs of DNA  Stitchers (Ligase): uses ATP to restore continuity of backbone of repaired strand

31. Big picture of DNA replication

32. Replication review

33. REPLICATION IN 3 STEPS  DNA replication results in two DNA molecules, each with one new strand (yellow) and one old strand (blue)

34. DNA replication animations  http://www.youtube.com/watch?v=4jtmO ZaIvS0 http://www.youtube.com/watch?v=4jtmO ZaIvS0 http://www.youtube.com/watch?v=4jtmO ZaIvS0  http://www.youtube.com/watch?v=gW3qZ F9cLIA http://www.youtube.com/watch?v=gW3qZ F9cLIA http://www.youtube.com/watch?v=gW3qZ F9cLIA  http://www.youtube.com/watch?v=oNW_ ykH3AvA http://www.youtube.com/watch?v=oNW_ ykH3AvA http://www.youtube.com/watch?v=oNW_ ykH3AvA  http://www.youtube.com/watch?v=hC_8y 8fNkCw http://www.youtube.com/watch?v=hC_8y 8fNkCw http://www.youtube.com/watch?v=hC_8y 8fNkCw

35. TED talk – DNA replication – Chromosomes- malaria  http://www.youtube.com/watch?v=dMPX u6GF18M http://www.youtube.com/watch?v=dMPX u6GF18M http://www.youtube.com/watch?v=dMPX u6GF18M