THE CHROMOSOMAL BASIS OF INHERITANCE. Copyright 2009 Pearson Education, Inc.

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1 THE CHOMOSOMAL BASIS OF INHEITANCE Copight 2009 Peason Education, Inc.

2 eview of Mendel s laws Mendel s Laws coelate with chomosome sepaation in meiosis The law of segegation depends on sepaation of homologous chomosomes in anaphase I The law of independent assotment depends on altenative oientations of chomosomes in metaphase I Copight 2009 Peason Education, Inc.

3 F 1 geneation All ound ellow seeds () Metaphase I of meiosis (altenative aangements)

4 F 1 geneation All ound ellow seeds () Metaphase I of meiosis (altenative aangements) Anaphase I of meiosis Metaphase II of meiosis

5 F 1 geneation All ound ellow seeds () Metaphase I of meiosis (altenative aangements) Anaphase I of meiosis Metaphase II of meiosis Gametes Fetilization among the F 1 plants F 2 geneation 9 :3 :3 :1

6 Genes on the same chomosome tend to go togethe Linked Genes Ae located close togethe on the same chomosome Tend to be inheited togethe Example studied b Bateson and Punnett Paental geneation: plants with puple flowes, long pollen cossed to plants with ed flowes, ound pollen The F 2 geneation did not show a 9:3:3:1 atio Most F 2 individuals had puple flowes, long pollen o ed flowes, ound pollen Copight 2009 Peason Education, Inc.

7 Expeiment Puple flowe PpLl PpLl Long pollen Phenotpes Puple long Puple ound ed long ed ound Explanation: linked genes Paental diploid cell PpLl Obseved offsping PL pl Meiosis Pediction (9:3:3:1) Most gametes PL pl Fetilization Spem PL pl PL PL Most offsping Eggs PL PL pl pl pl pl PL pl 3 puple long : 1 ed ound Not accounted fo: puple ound and ed long

8 Expeiment Puple flowe PpLl PpLl Long pollen Phenotpes Puple long Puple ound ed long ed ound Obseved offsping Pediction (9:3:3:1)

9 Explanation: linked genes Paental diploid cell PpLl PL pl Meiosis Most gametes PL pl Fetilization Spem PL pl PL PL Most offsping Eggs PL PL pl pl pl pl PL pl 3 puple long : 1 ed ound Not accounted fo: puple ound and ed long

10 9.18 Cossing ove poduces new combinations of alleles Linked alleles can be sepaated b cossing ove ecombinant chomosomes ae fomed Thomas Hunt Mogan demonstated this in eal expeiments Geneticists measue genetic distance b ecombination fequenc Copight 2009 Peason Education, Inc.

11 A B A B A b a b a B a b Tetad Cossing ove Gametes

12 Expeiment Ga bod, long wings (wild tpe) GgLl Female Black bod, vestigial wings ggll Male Ga long Offsping Black vestigial Ga vestigial Black long Paental phenotpes ecombinant phenotpes ecombination fequenc = 391 ecombinants 2,300 total offsping = 0.17 o 17%

13 Explanation GgLl (female) G L g l g l g l ggll (male) G L g l G l g L g l Eggs Spem G L g l G l g L g l g l g l g l Offsping

14 Cossove data to map genes Genetic maps Show the ode of genes on chomosomes Aange genes into linkage goups epesenting individual chomosomes Chomosome g c l 17% 9% 9.5% ecombination fequencies

15 Shot aistae Mutant phenotpes Black bod (g) Cinnaba ees (c) Vestigial wings (l) Bown ees Long aistae (appendages on head) Ga bod (G) ed ees (C) Wild-tpe phenotpes Nomal wings (L) ed ees

16 SEX CHOMOSOMES AND SEX-LINKED GENES Copight 2009 Peason Education, Inc.

17 Copight 2009 Peason Education, Inc.

18 Chomosomes detemine sex X- sstem in mammals, fuit flies XX = female X = male X

19 (male) 44 + X Paents diploid cells (female) 44 + XX 22 + X X Spem Egg 44 + XX Offsping (diploid) 44 + X

20 Chomosomes detemine sex X-O sstem in gasshoppes and oaches XX = female; XO = male 22 + XX 22 + X

21 Chomosomes detemine sex Z-W in sstem in bids, butteflies, and some fishes ZW = female, ZZ = male 76 + ZW 76 + ZZ

22 Chomosomes detemine sex Chomosome numbe in ants and bees Diploid = female; haploid = male 32 16

23 9.21 Sex-linked genes exhibit a unique patten of inheitance Sex-linked genes ae located on eithe of the sex chomosomes X-linked genes ae passed fom mothe to son and mothe to daughte X-linked genes ae passed fom fathe to daughte -linked genes ae passed fom fathe to son Copight 2009 Peason Education, Inc.

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25 Female Male X X X Spem X Eggs X X X X = ed-ee allele = white-ee allele

26 Female Male X X X Spem X X X X X Eggs X X X X

27 Female Male X X X Spem X X X X X Eggs X X X X

28 9.22 CONNECTION: Sex-linked disodes affect mostl males Males expess X-linked disodes such as the following when ecessive alleles ae pesent in one cop Hemophilia Coloblindness Duchenne muscula dstoph Copight 2009 Peason Education, Inc.

29 Queen Victoia Albet Alice Louis Alexanda Cza Nicholas II of ussia Alexis

30 9.23 EVOLUTION CONNECTION: The chomosome povides clues about human male evolution Similaities in chomosome sequences Show a significant pecentage of men elated to the same male paent Demonstate a connection between people living in distant locations Copight 2009 Peason Education, Inc.

31 ou should now be able to 1. Explain and appl Mendel s laws of segegation and independent assotment 2. Distinguish between tems in the following goups: allele gene; dominant ecessive; genotpe phenotpe; F 1 F 2 ; heteozgous homozgous; incomplete dominance codominance 3. Explain the meaning of the tems locus, multiple alleles, pedigee, pleiotop, polgenic inheitance Copight 2009 Peason Education, Inc.

32 ou should now be able to 4. Descibe the diffeence in inheitance pattens fo linked genes and explain how ecombination can be used to estimate gene distances 5. Descibe how sex is inheited in humans and identif the patten of inheitance obseved fo sex-linked genes 6. Solve genetics poblems involving monohbid and dihbid cosses fo autosomal and sex-linked taits, with vaiations on Mendel s laws Copight 2009 Peason Education, Inc.