Gregor Johann Mendel ( ) Responsible for the Laws governing Inheritance of Traits

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Erica Lynch
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Gego Johann Mendel (822-884) esponsible fo the Laws govening

pea plants Developed the laws of inheitance Mendel's wok was not

Mendel cultivated and tested some 28,000 pea plants He found that

Genetics" Paticulate Inheitance Mendel stated that physical taits ae

1 Gego Johann Mendel ( ) esponsible fo the Laws govening Inheitance of Taits Austian monk Studied the inheitance of taits in pea plants Developed the laws of inheitance Mendel's wok was not ecognized until the tun of the 20th centuy Between 856 and 863, Mendel cultivated and tested some 28,000 pea plants He found that the plants' offsping etained taits of the paents Called the Fathe of Genetics" Paticulate Inheitance Mendel stated that physical taits ae inheited as paticles Mendel did not know that the paticles wee actually Chomosomes & DNA

Genetic Teminology Tait - any chaacteistic that can be passed fom paent to offsping Heedity - passing of taits fom paent to offsping Genetics - study of heedity Types of Genetic

2 Genetic Teminology Tait - any chaacteistic that can be passed fom paent to offsping Heedity - passing of taits fom paent to offsping Genetics - study of heedity Types of Genetic Cosses Monohybid coss - coss involving a single tait e.g. flowe colo Dihybid coss - coss involving two taits e.g. flowe colo & plant height Punnett Squaes Used to help solve genetics poblems

Making Punnett Squaes Designe Genes Alleles - two foms of a gene (dominant & ecessive) Dominant - stonge of two genes expessed in the hybid; epesented by a capital lette () ecessive - gene that

3 Making Punnett Squaes Designe Genes Alleles - two foms of a gene (dominant & ecessive) Dominant - stonge of two genes expessed in the hybid; epesented by a capital lette () ecessive - gene that shows up less often in a coss; epesented by a lowecase lette () Moe Teminology Genotype - gene combination fo a tait (e.g.,, ) Phenotype - the physical featue esulting fom a genotype (e.g. ed, white)

Genotype & Phenotype in Flowes Genotype of alleles: = ed flowe = yellow flowe All genes occu in pais, so 2 alleles affect a chaacteistic Possible combinations ae: Genotypes Phenotypes ED ED YELLOW

4 Genotype & Phenotype in Flowes Genotype of alleles: = ed flowe = yellow flowe All genes occu in pais, so 2 alleles affect a chaacteistic Possible combinations ae: Genotypes Phenotypes ED ED YELLOW Genotypes Homozygous genotype - gene combination involving 2 dominant o 2 ecessive genes (e.g. o ); also called pue Heteozygous genotype - gene combination of one dominant & one ecessive allele (e.g. ); also called hybid Genes and Envionment Detemine Chaacteistics

5 Mendel s Pea Plant Expeiments Why peas, Pisum sativum? Can be gown in a small aea Poduce lots of offsping Poduce pue plants when allowed to self-pollinate seveal geneations Can be atificially coss-pollinated epoduction in Floweing Plants Pollen contains spem Poduced by the stamen Ovay contains eggs Found inside the flowe Pollen caies spem to the eggs fo fetilization Self-fetilization occus within the same flowe Coss-fetilization occus between diffeent flowes

Coveed each flowe with a cloth bag He taced taits though the seveal

6 Mendel s Expeimental Methods Mendel hand-pollinated flowes using a paintbush He could snip the stamens to pevent self-pollination Coveed each flowe with a cloth bag He taced taits though the seveal geneations Site of Gego Mendel s expeimental gaden in the Czech epublic

Pod Shape --- Smooth (S) o winkled (s) 4. Pod Colo --- Geen (G) o Yellow (g) 5.

7 How Mendel Began Mendel poduced pue stains by allowing the plants to selfpollinate fo seveal geneations Eight Pea Plant Taits. Seed shape --- ound () o Winkled () 2. Seed Colo ---- Yellow (Y) o Geen (y) 3. Pod Shape --- Smooth (S) o winkled (s) 4. Pod Colo --- Geen (G) o Yellow (g) 5. Seed Coat Colo ---Gay (G) o White (g) 6. Flowe position---axial (A) o Teminal (a) 7. Plant Height --- Tall (T) o Shot (t) 8. Flowe colo --- Puple (P) o white (p)

9 Does the obseved atio match the theoetical atio? The theoetical o expected atio of plants poducing ound o winkled seeds is 3 ound : winkled Mendel s obseved atio was 2.96: The discepancy is due to statistical eo The lage the sample the moe nealy the esults appoximate to the theoetical atio

Geneation Gap Paental P Geneation = the paental geneation in a beeding expeiment. F geneation = the fist-geneation offsping in a beeding expeiment.

10 Geneation Gap Paental P Geneation = the paental geneation in a beeding expeiment. F geneation = the fist-geneation offsping in a beeding expeiment. (st filial geneation) Fom beeding individuals fom the P geneation F 2 geneation = the second-geneation offsping in a beeding expeiment. (2nd filial geneation) Fom beeding individuals fom the F geneation Coss 2 Pue Plants TT x tt esults in all Hybids Tt Coss 2 Hybids get 3 Tall & Shot TT, Tt, tt

11 Monohybid Cosses P Monohybid Coss Tait: Seed Shape Alleles: ound Winkled Coss: ound seeds x Winkled seeds x Genotype: Phenotype: ound Genotypic atio: All alike Phenotypic atio: All alike P Monohybid Coss eview Homozygous dominant x Homozygous ecessive Offsping all Heteozygous (hybids) Offsping called F geneation Genotypic & Phenotypic atio is ALL ALIKE

12 F Monohybid Coss Tait: Seed Shape Alleles: ound Winkled Coss: ound seeds x ound seeds x Genotype:,, Phenotype: ound & winkled G.atio: :2: P.atio: 3: F Monohybid Coss eview Heteozygous x heteozygous Offsping: 25% Homozygous dominant 50% Heteozygous 25% Homozygous ecessive Offsping called F2 geneation Genotypic atio is :2: Phenotypic atio is 3:

13 And Now the Test Coss Mendel then cossed a pue & a hybid fom his F 2 geneation This is known as an F o test coss 2 Thee ae two possible testcosses: st TEST: Homozygous dominant x Hybid 2nd TEST: Homozygous ecessive x Hybid F 2 Monohybid Coss ( st ) Tait: Seed Shape Alleles: ound Winkled Coss: ound seeds x ound seeds x Genotype:, Phenotype : Genotypic atio: : ound Phenotypic atio: All alike

14 F Monohybid Coss (2nd) 2 Tait: Seed Shape Alleles: ound Winkled Coss: Winkled seeds x ound seeds x Genotype:, Phenotype: ound & Winkled G. atio: : P.atio: : F Monohybid Coss eview 2 Homozygous x heteozygous(hybid) Offsping: 50% Homozygous o 50% Heteozygous Phenotypic atio is : o all the same depending on coss Called Test Coss because the offsping have SAME genotype as paents Pactice You Cosses Wok the P, F, and both F Cosses fo each of the othe Seven Pea Plant Taits 2

Genetics Using Punnett Squares

Genetics Using Punnett Squares Genetics Using Punnett Squaes Ealy Genetics The study of genetics began with obsevations made by Gego Mendel. Afte noticing that the flowes his pea plants wee eithe violet o white, Mendel began to study