1 Mendels Laws 2 Variations on Mendels Laws

1. Mendel’s Laws 2. Variations on Mendel’s Laws 3. Chromosomal Basis of Inheritance 4. Sex Linked Chromosomes and Sex-linked Genes

© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

White 1 Removal of stamens Stamens Carpel Parents (P) 2 Transfer Purple of pollen 3 Carpel matures into pea pod 4 Seeds from pod planted Offspring (F 1)

Traits Character Dominant Recessive Purple White Axial Terminal Yellow Green Round Wrinkled Inflated Constricted Green Yellow Tall Dwarf Flower color Flower position Seed color Seed shape Pod color Stem length

law of segregation © 2012 Pearson Education, Inc.

The Experiment P generation (true-breeding parents) Purple flowers F 1 generation White flowers All plants have purple flowers Fertilization among F 1 plants (F 1 F 1) F 2 generation 3 4 1 of plants 4 have purple flowers have white flowers

law of segregation blending © 2012 Pearson Education, Inc.

1. 2. © 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

Punnett square © 2012 Pearson Education, Inc.

The Explanation P generation Genetic makeup (alleles) White flowers Purple flowers PP pp Gametes All P All p F 1 generation (hybrids) All Pp Gametes 1 2 P Alleles segregate 1 2 p Fertilization Sperm from F 1 plant F 2 generation P Phenotypic ratio 3 purple : 1 white Genotypic ratio 1 PP : 2 Pp : 1 pp P Eggs from F 1 plant p p PP Pp Pp pp

F 2 generation Phenotypic ratio 3 purple : 1 white Sperm from F 1 plant P Eggs from F 1 plant Genotypic ratio p 1 PP : 2 Pp : 1 pp P p PP Pp Pp pp

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Gene loci P a B P a b Dominant allele Homologous chromosomes Genotype: PP Homozygous for the dominant allele aa Homozygous for the recessive allele Recessive allele Bb Heterozygous, with one dominant and one recessive allele

law of independent assortment © 2012 Pearson Education, Inc.

P generation RRYY Gametes RY F 1 generation rryy ry Sperm Rr. Yy 1 4 RY 1 4 r. Y 1 4 Ry 1 4 ry Sperm 1 2 F 2 generation RY 1 2 ry RY Eggs 1 2 ry 1 4 RY 1 4 r. Y Eggs 1 4 The hypothesis of dependent assortment Data did not support; hypothesis refuted RRYY Rr. YY RRYy Rr. YY Rr. Yy rr. YY Ry RRYy Rr. Yy RRyy Rr. Yy rr. Yy Rryy ry 9 16 Yellow round 3 16 Green round 3 16 Yellow wrinkled 1 16 Green wrinkled The hypothesis of independent assortment Actual results; hypothesis supported

Rr. Yy F 1 generation Sperm 1 4 RY 1 4 r. Y RRYY Rr. YY Eggs 1 4 RY 1 4 r. Y Rr. YY rr. YY 1 4 Ry RRYy Rr. Yy 1 4 ry Rr. Yy rr. Yy Ry RRYy Rr. Yy RRyy Rr. Yy rr. Yy Rryy ry 9 16 Yellow round 3 16 Green round 3 16 Yellow wrinkled 1 16 Green wrinkled The hypothesis of independent assortment Actual results; hypothesis supported

law of independent assortment © 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

F 1 genotypes Bb male Bb female Formation of eggs Formation of sperm 1 2 B b Sperm 1 1 (2 2 ) 1 2 F 2 genotypes B b b 1 4 B 1 4 b B 1 4 Eggs 1 2 B B b b 1 4

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Dominant Traits Recessive Traits Freckles No freckles Widow’s peak Straight hairline Free earlobe Attached earlobe

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First generation (grandparents) Ff Second generation (parents, aunts, FF and uncles) or Ff Third generation (two sisters) Female Male Attached Free ff Ff ff ff Ff Ff Ff ff ff FF or Ff

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Incomplete dominance © 2012 Pearson Education, Inc.

P generation Red RR White rr Gametes R r F 1 generation Pink hybrid Rr Gametes 1 2 R 1 2 r Sperm 1 1 R 2 2 r F 2 generation 1 R 2 RR r. R 1 r 2 Rr rr Eggs

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© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

Blood Group (Phenotype) Genotypes Carbohydrates Present on Red Blood Cells A IAIA or IAi Carbohydrate A Carbohydrate B B IBIB or IBi AB IAIB O ii Antibodies Present in Blood Reaction When Blood from Groups Below Is Mixed with Antibodies from Groups at Left O A B AB Anti-A Carbohydrate A and Carbohydrate B Neither None Anti-A Anti-B No reaction Clumping reaction

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An individual homozygous for the sickle-cell allele Produces sickle-cell (abnormal) hemoglobin The abnormal hemoglobin crystallizes, causing red blood cells to become sickle-shaped Sickled cell The multiple effects of sickled cells Damage to organs Other effects Kidney failure Heart failure Spleen damage Brain damage (impaired mental function, paralysis) Pain and fever Joint problems Physical weakness Anemia Pneumonia and other infections

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P generation aabbcc AABBCC (very light) (very dark) F 1 generation Aa. Bb. Cc Sperm 1 8 F 2 generation 1 8 1 8 1 8 Fraction of population Eggs 1 8 1 8 1 8 1 64 6 64 15 64 20 64 15 64 6 64 1 64 Skin color

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© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

F 1 generation R r All yellow round seeds (Rr. Yy) y Y r R Y R y Metaphase I of meiosis r R Y y r r R Y y Anaphase I Y y R r Y y Metaphase II r R Y y Gametes Y Y R R 1 4 RY y y r r 1 4 Y Y r r ry F 2 generation 9 Fertilization : 3 : 1 1 4 r. Y y y R R 1 4 Ry

Sperm 1 1 4 RY 4 r. Y 4 Ry 4 ry 1 4 RY RRYY Rr. YY RRYy Rr. Yy 1 4 r. Y Eggs 1 Ry 4 1 ry 4 Rr. YY rr. YY Rr. Yy rr. Yy RRYy Rr. Yy RRyy Rr. Yy rr. Yy Rryy rryy 9 16 Yellow round 3 16 Green round 3 16 Yellow wrinkled 1 16 Green wrinkled

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The Experiment Purple flower Pp. Ll Phenotypes Pp. Ll Long pollen Observed offspring 284 21 21 55 Purple long Purple round Red long Red round Prediction (9: 3: 3: 1) 215 71 71 24 The Explanation: Linked Genes PL Parental diploid cell Pp. Ll pl Meiosis Most gametes pl PL Fertilization Sperm PL PL pl pl pl PL Most offspring Eggs pl pl 3 purple long : 1 red round Not accounted for: purple round and red long

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p L p l PL Parental gametes pl Tetrad Crossing over (pair of homologous chromosomes) p L P l Recombinant gametes

The Explanation The Experiment Gray body, long wings (wild type) Black body, vestigial wings Gg. Ll ggll Female Male Gg. Ll Female GL Parental phenotypes Recombination frequency gl Gl 206 Black long 185 Recombinant phenotypes 391 recombinants 0. 17 or 17% 2, 300 total offspring ggll Male gl g. L Eggs Black vestigial Gray vestigial 944 gl g l Sperm Offspring GL g l G l g L g l g l Parental 965 gl Crossing over Offspring Gray long GL Recombinant

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Section of chromosome carrying linked genes g c l 17% 9% 9. 5% Recombination frequencies

Mutant phenotypes Short aristae Black body (g) Cinnabar Vestigial wings eyes (l) (c) Red Long aristae Gray Normal eyes (appendages body wings (C) on head) (G) (L) Wild-type phenotypes Brown eyes Red eyes

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© 2012 Pearson Education, Inc.

X Y

© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc.