Tetrad analysis

1. Tetrad analysis אסקוס ספורה/נבג/תוצר מיוזה טטרדה

4. Replica plating

5. Replica plating -URA -TRP -ADE -LYS YePD URA3 TRP1 ade2 lys2 URA3 trp1 ade2 lys2

7. ab X a+b+

8. A B a b A B A b A B A b a b a B a b a B PD = NPD

9. A B A B X a b a b A B A B a b A b A B a B a b A B a b PD only TT a b

10. Thus RF=1/2TT אבל מה עם הרקומבינציות הכפולות?

13. כלומר החישוב הקודם אינו כולל רקומבינציות כפולות ויתרה מכך הוא מטעה כי הTT כולל גם כפולות....

15. Assuming that, in our hypothetical cross of a+b+ × a b, the observed frequencies of the ascus classes are 56 percent PD, 41 percent T, and 3 percent NPD. Using the formula, we find the map distance between the a and b loci to be:

16. Let us compare this value with that obtained directly from the RF. Recall that the formula is: In our example, This RF value is 6 m.u. less than the estimate we obtained by using the map-distance formula because we could not correct for double crossovers in the RF analysis.

17. Summary PD=NPD - No linkage PD only high linkage maybe the same gene PD>TT>NPD -Linkage RF=1/2(TT+6NPD)

19. Repair, and Recombination

22. E. Coli SOS system Emergency response that allow the insertion of non specific base! In bacteria its DinB, UmuC and UmuD that encode for pol IV and V, the error prone polymerase that incorporate an arbitrary base across to the damaged base.

23. Pol eta/iota

28. Direct reversal By photolyase

29. Base excision repair • Start with glycosylase that break the sugar-base bond* and release the altred base and generating apurinic or apyrimidinic sites. * For example guanine +EMS -> 0-6-ethylgunine (can mispaired with Thymine)

33. Nucleotide excision repair (NER) in bacteria

34. Nucleotide excision repair (NER) in yeast

37. XPD and XPB – helicase XPG and XPF - endonuclase

38. Cockayne syndrome • Mutation in CSA or CSB causes to retinal degeneration, hearing impairment, ataxia and photosensitivity • Die very young

39. Tricothiodystrophy (TTD) • Mutations in XPD

40. TTD Human shows photosensetivity, brittle hair, skin defects and short life span. XPD -/- mice show also wasting, scoliosis, osteophoresis and melanocyte loss. WT 3m 15m WT TTD

41. Mismatch repair in bacteria

42. Mismatch repair (NER) in human