Your SlideShare is downloading. ×
Biology 2250 Principles of Genetics
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Biology 2250 Principles of Genetics

1,247
views

Published on


0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
1,247
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
49
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide
  • 27
  • 1
  • 22 21
  • 7 6 6 6
  • 8 7 7 7
  • 9 8 8 8
  • 10 9 9
  • 21 20
  • 23 22
  • 24 23
  • 25 24
  • 26 25
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 22 21
  • Transcript

    • 1. Biology 2250 Principles of Genetics Announcements Lab 3 Information: B2250 (Innes) webpage download and print before lab. Virtual fly: log in and practice http://biologylab.awlonline.com/ people that have ALREADY picked up their exams should see Dr. Carr for a re-marking of p. 2
    • 2. Weekly Online Quizzes Marks Oct. 14 - Oct. 25 Example Quiz 2** for logging in Oct. 21- Oct. 25 Quiz 1 2 Oct. 28 Quiz 2 2 Nov. 4 Quiz 3 2 Nov. 10 Quiz 4 2
    • 3. B2250 Readings and Problems Ch. 4 p. 100 – 112 Prob: 10, 11, 12, 18, 19 Ch. 5 p. 118 – 129 Prob: 1 – 3, 5, 6, 7, 8, 9 Ch. 6 p. 148 – 165 Prob: 1, 2, 3, 10
    • 4. Mendelian Genetics Topics: -Transmission of DNA during cell division Mitosis and Meiosis - Segregation - Sex linkage ( problem: how to get a white-eyed female ) - Inheritance and probability - Independent Assortment - Mendelian genetics in humans - Linkage - Gene mapping - Tetrad Analysis (mapping in fungi) - Extensions to Mendelian Genetics - Gene mutation - Chromosome mutation - Quantitative and population genetics     
    • 5. Mendelian Inheritance Determining mode of inheritance : - single gene or more complicated - recessive or dominant - sex linked or autosomal Approach: cross parents observed progeny compare with expected
    • 6. Equal segregation of two members of a gene pair Mendel’s First Law Aa ½ A gametes ½ a gametes P(a) = ½ P(A) = ½ Meiosis: diploid nucleus divides produces haploid nuclei
    • 7. Mendel’s Second Law Independent assortment: during gamete formation, the segregation of one gene pair is independent of other gene pairs.
    • 8. Two Characters Monohybrid Cross parents differ for a single character (single gene ); seed shape Dihybrid Cross parents differ for two characteristics (two genes)
    • 9. Dihybrid Two Characters : 1. Seed colour yellow green Y y 2. Seed shape Round wrinkled R r 4 phenotypes
    • 10. Dihybrid RRyy X rrYY Ry rY RrYy DIHYBRID P F 1 Gametes
    • 11. F 1 Dihybrid ----->F 2 F 1 RrYy RrYy X RrYy F 2 9 315 round, yello w 3 108 round, green 3 101 wrinkled, yellow 1 32 wrinkled, green Total 556
    • 12. Producing the F 2 YyRr X YyRr 1. F 1 Gametes  produce F 2 2. Genotypes 3. Phenotypes F 1 F 2
    • 13. Independent Assortment Two gene systems: 1. Gametes from dihybrid 4 x 4 = 16 YyRr: ¼ YR Yr yR yr ¼ YR 1/16YYRR Yr yR yr Male gametes Female gametes F 2
    • 14. Independent Assortment 2. F 2 Genotypes 3 x 3 = 9 ¼ RR ½ Rr ¼ rr ¼ YY 1/16 YYRR ½ Yy ¼ yy F 2 YyRr X YyRr
    • 15. Independent Assortment 3. F 2 Phenotypes 2 x 2 = 4 ¾ R- ¼ rr ¾ Y- 9/16 R-Y- ¼ yy YyRr X YyRr
    • 16. F 1 9 Genotypes 4 phenotypes YY RR YY Rr Yy RR Yy Rr YY rr Yy rr yy RR yy Rr yy rr YyRr x YyRr Y-R- Y-rr yyR- yyrr
    • 17. Independent Assortment Any number of independent genes: Genes Phenotypes Genotypes 1 2 3 2 4 (2 x2) 9 (3 x 3) 3 8 (2x2x2) 27 (3 x 3 x 3) n 2 n 3 n
    • 18. Mendelian Genetics in Humans Determining mode of inheritance Problems: 1. long generation time 2. can not control mating Alternative: * information from matings that have already occurred “ Pedigree ”
    • 19. Human Pedigrees
      • Pedigree analysis:
      • trace inheritance of disease or condition
      • provide clues for mode of inheritance
      • ( dominant vs. recessive )
      • ( autosomal vs. sex linked )
      • however, some pedigrees ambiguous
    • 20. Human Pedigrees 1. Ambiguous: 2. Unambiguous: Affected female Normal male Normal female
    • 21. Clues (non sex - linked) Recessive : 1. individual expressing trait has two normal parents 2. two affected parents can not have an unaffected child.
    • 22. Rare Recessive A- (AA or Aa) Cousins (inbreeding) Rare = AA
    • 23. Clues Dominant: 1. every affected person has at least one affected parent 2. each generation will have affected individuals
    • 24. Dominant All genotypes known Not AA
    • 25. Examples Recessive: - phenylketonuria (PKU) - hemophilia (sex linked) - cystic fibrosis - albinism Dominant: - huntingtons chorea - brachydactyly (short fingers) - polydactyly (extra fingers) - achondroblasia (dwarf)
    • 26. http://www. ncbi . nlm . nih . gov / entrez /query. fcgi ?db=OMIM 2n = 46
    • 27.  
    • 28. Brachydactyly Bb short fingers bb normal Bb bb
    • 29. http://omia.angis.org.au/
    • 30.  
    • 31.  
    • 32. http://www.biology. arizona . edu / mendelian _genetics/ mendelian _genetics.html Online Tutorial:
    • 33. Solving Genetics Problems
      • Don’t panic!
      • Carefully read the problem
      • What information is given? Know the terms used.
      • What aspect of genetics does the problem address?
    • 34. X-linked Dominant 1. affected male ---> all daughters affected no sons aa x AY ----> Aa, aY 2. affected female ----> ½ sons, ½ daughters affected Aa x aY ----> AY, aY, aa, Aa * * Sex Linked Inheritance
    • 35. X-Linked Dominant 1. 2. All daughters affected, no sons 1/2 daughters affected, 1/2 sons affected
    • 36. X-linked Inheritance X-linked recessive : 1. more males than females show recessive phenotype 2. affected female ------> both mother and father have recessive allele A a x a Y --------> a a
    • 37. X-linked Inheritance X-linked recessive : 3. affected male ----> mother carries allele A a x AY -----> a Y 4. affected male -----> no affected offspring AA x a Y ----> AY, Aa carrier carrier
    • 38. X-Linked Recessive Mother carrier
    • 39. Sex Linked Inheritance (examples)
      • X linked genes
      • Humans: - colour blindness
      • - hemophilia
      • More common in males ( hemizygous aY)
      • X linked recessives expressed
    • 40. X-linked recessive hemophilia Queen Victoria (carrier) QE II Hemophilic male Carrier female
    • 41. X – linked disease genes
    • 42. Mendelian Genetics Topics: -Transmission of DNA during cell division Mitosis and Meiosis - Segregation (Monohybrid) - Sex linkage - Inheritance and probability - Independent Assortment (Dihybrid) - Mendelian genetics in humans (Pedigree)
    • 43. Mendel’s Second Law Independent assortment: during gamete formation, the segregation of one gene pair is independent of other gene pairs. Genes independent because they are on different chromosomes
    • 44. Independent Assortment F 1 AaBb X AaBb F 2 9 A-B- 3 A-bb 3 aaB- 1 aabb 4 phenotypes AABB AaBb AaBB AABb Genotypes Aabb, AAbb aaBb, aaBB
    • 45. Independent Assortment Test Cross AaBb X aabb gametes ab 1/4 AB A a B b 1/4 Ab A a b b 1/4 aB a a B b 1/4 ab a a b b 4 phenotypes 4 genotypes
    • 46. Fig 6-6 Independent Assortment Interchromosomal Recombination AB ab Ab aB Inferred F 1 gamete types
    • 47. A a B b A a b B Meiosis I OR (Genes) Correlation of genes and Chromosomes during meiosis A a 4 gamete types
    • 48. Linkage of Genes - Many more genes than chromosomes - Some genes must be linked on the same chromosome; therefore not independent
    • 49. Complete Linkage P A B a b F 1 A B a b AaBb F 1 gametes A B AB Parental Parental a b ab X dihybrid
    • 50. Recombinant Gametes ? Crossing over: - exchange between homologous chromosomes
    • 51. Crossing over in meiosis I Meiosis I - homologous chromosomes pair - reciprocal exchange between non-sister chromatids Ch 4 meiosis animation: http://www. whfreeman .com/ mga /
    • 52. Crossing over in meiosis I (animation)
    • 53. Gamete Types F 1 A B a b AaBb gametes A B AB Parental a b ab Parental A b Ab Recomb. a B aB Recomb.
    • 54. 1. Ways to produce dihybrid A B a b A B a b A B AaBb a b (dihybrid ) Gametes: AB P ab P Ab R aB R X P Cis Note: Chromatids omitted
    • 55. 2. Ways to produce dihybrid A b a B A b a B AaBb A b trans (dihybrid ) a B Gametes: P Ab P aB R AB R ab X P
    • 56. Two ways to produce dihybrid A B a b A b a B A B a b A b a B cis A B AaBb A b trans a b (dihybrid ) a B Gametes: AB P Ab ab P aB Ab R AB aB R ab X X P
    • 57. Fig 6-6 Independent Assortment Linkage Fig 6-11 Interchromosomal Intrachromosomal
    • 58. Example Test Cross AaBb X aabb ab Exp. Obs. AB AaBb 25 10 R Ab Aabb 25 40 P aB aaBb 25 40 P ab aabb 25 10 R 100 100 How to distinguish: Parental  high freq. Recombinant  low freq.
    • 59. Example (cont.) Gametes: AB R Ab P aB P ab R Therefore dihybrid: A b (trans) a B
    • 60. Linkage Maps Genes close together on same chromosome: - smaller chance of crossovers between them - fewer recombinants Therefore: percentage recombination can be used to generate a linkage map
    • 61. Linkage maps A B large # of recomb. a b C D small number of recombinants c d Alfred Sturtevant (1913)
    • 62. Linkage maps example Testcross progeny: P AaBb 2146 R Aabb 43 R aaBb 22 P aabb 2302 Total 4513 1.4 map units 65 4513 = 1.4 % RF A 1.4 mu B
    • 63. Additivity of map distances separate maps A B A C 7 2 combine maps C A B 2 7 or Locus A C B (pl. loci ) 2 5
    • 64. Summary Mendelian Genetics: Monohybrid cross (segregation): - ratios (3:1, 1:2:1, 1:1) - dominance, recessive - autosomal, sex-linked - probability - pedigrees Dihybrid Cross (Indep. Assort.): - ratios (9:3:3:1, 1:1:1:1) - linkage (deviation from I.A.) - recombination - linkage maps
    • 65. Linkage Deviations from independent assortment Dihybrid  gametes 2 parent (noncrossover) common 2 recombinant (crossover) rare % recombinants a function of distance between genes % RF = map distance
    • 66. Linkage maps Tomato Drosophila

    ×