2. DNA

3. The Nuclear genome consists of DNA in the nucleus of eukaryotic cells – this is what we typically think of as our Genome: A Genome is the unique set of chromosomes (or DNA) in one cell of an organism. Humans have 2 sets of chromosomes (one from each parent: we are diploid.) Our genome consists of 3 x10 9 base pairs ~25,000 genes (no one knows exactly yet).

4. Chloroplast Mitochondrion Nucleus Plant CellAnimal Cell

5. Chloroplasts (photosynthesis machinery in plants, algae) have their own DNA (called the Plastid genome) 7.5-25 x 10 3 base pairs 100-1000 copies depending on whether the cell is actively dividing (more when dividing). ~100 genes Mitochondria have their own DNA (called the Mitochondrial genome) ~1.7 x 10 4 base pairs several copies ~40 genes

7. Nucleic Acids DNA RNA

8. DNA Deoxyribonucleic acid double helix “intelligent molecule” made of nucleotides

9. One human cell Has ~1 meter of DNA DNA is partitioned into 46 separate linear molecules (chromosomes, 23 from each parent) All of it is crammed into the cell's nucleus (a few micrometers) Robert H. Austin, James P. Brody, Edward C. Cox, Thomas Duke and Wayne Volkmuth FEBRUARY 1997 PHYSICS TODAY image from the National Human Genome Research Institute (NHGRI) Genetic Illustrations. CELL Nucleus

13. 2 nm 11 nm 300 nm 30 nm 700 nm 1400 nm DNA Chromatin Chromosome Richarddawkins.net

14. Nucleotide Sugar (deoxyribose) Phosphate Nitrogenous Base adenine (A) thymine (T) cytosine (C) guanine (G)

18. DNA is double-stranded adenine is always across from thymine cytosine is always across from guanine bases are held across from each other by weak hydrogen bonds A T C G

19. This OH group is replaced by H (hydrogen atom) in Deoxy-ribose The Sugar in the “backbone” is RNA: ribose DNA: deoxyribose

20. 5’ 3’ 5’ DNA is anti-parallel: One strand is 5’to 3’ The strand across from it is 3’ to 5’

22. How do We Know the Structure of DNA? Watson & Crick 1953

24. Diffraction Patterns Reciprocal Space http://www.matter.org.uk/diffraction/geometry/3D_reciprocal_lattices.htm X-ray crystallography revisited Click here for a groovy interactive experience (Grab and drag one of the white dots)

25. DNA X-ray diffraction pattern X-ray crystallography revisited

26. 34 Angstroms X-ray crystallography revisited

27. 3.4 Angstroms X-ray crystallography revisited

31. X-ray Diffraction pattern → Molecular Structure 1953 Discovery → Nobel Prize

32. Why x-rays? Wavelength of diffracted light should match size of object for optimal resolution

33. A DNA molecule not a rigid, static structure (as x-ray diffraction pictures might suggest) under constant thermal fluctuations local twisting, stretching, bending, and unwinding of the double-strands. http://www.uic.edu/classes/phys/phys461/phys450/ANJUM04/ X-ray crystallography revisited

34. The most common DNA structure in solution is B-DNA. DNA has several helical conformations A-DNA, Z-DNA, S- DNA Under conditions of applied force low hydration... A B Z

35. A-DNA Short and broad Low hydration Right handed helix 25.5A diameter 2.3A rise/base pair ~11 bases/ turn B-DNA Long and thin Most common in solution Right-handed helix 27.3 A diameter 3.4 A rise/base pair ~ 10 bases/turn Z-DNA Longer and thinner Left-handed helix 18.4 A diameter 3.8 A rise/base pair ~12 bases/ turn

36. DNA Replication 2 strands of DNA “unzip” - separate primers are placed on each strand DNA polymerase (an enzyme) builds new strands of DNA, using the original strands as templates

38. RNA Ribonucleic acid single stranded also made of nucleotides

39. RNA nucleotides Sugar (ribose) Phosphate nitrogenous base adenine cytosine guanine uracil

42. Types of RNA mRNA: messenger RNA, carries the DNA code out of the nucleus to the ribosome tRNA: transfer RNA, carries amino acids to the ribosome rRNA: ribosomal RNA, part of the ribosome

43. Transcription (making RNA) DNA unzips one strand of DNA acts as a template RNA polymerase reads the DNA bases RNA nucleotides are placed across from the complimentary DNA bases RNA separates from DNA DNA zips back up

47. The “code” of DNA is the order of the bases The code is universal among organisms DNA from one organism can be read in the cells of another organism