2. GENETICS: Our Family Tree

3. It’s all Relative! --Did you know we share 99.9% of our genes with other humans? --95% of our genes with chimpanzees? --92% of our genes with a mouse? --So was Dr. Seuss thinking about genetics?

4. It’s all in the genes! Genes -- the unit of heredity --carry the information about our traits --found in the chromosomes --pass trait information from parent to offspring

5. Combination Platter Egg + Sperm = Y U --You inherited 23 chromosomes from each parent. --Each of those chromosomes contained ALLELES. --Allele = different form of same gene. --The combination of those alleles = Y U!

6. Who’s the daddy? --Genetics is the study of heredity. --Gregor Mendel is the father of genetics. --He was a priest in a monastery who enjoyed gardening. --He was interested in the different characteristics of pea plants (yuck  ).

7. The Birds and the Peas --Mendel cross-pollinated 2 purebred pea plants. --He took the pollen from one plant and fertilized it with the other plant. --WHY? To see what he could see – the characteristics of the offspring!

8. Mendel’s Peas --Mendel noticed the size of pea plants varied. --He wondered what would happen if he crossed purebred plants? --Purebred – Tall or Short (no in betweens—ex. mediums)

9. Mendel’s cross between tall pea plants yielded all tall pea plants. His cross between small pea plants yielded all small pea plants. Tall x Tall = TallSmall x Small = Small X X== PP PPF 1

10. Mendel’s cross of tall plants with small plants resulted in tall plants. X = F 1 PP

11. Mendel then crossed the first generation (F 1 ) tall plants and the results (F 2 ) were 1 out of 4 Small. X = F1F1 F 2 F 2 Second Generation

12. Mendelalian Genetics --What did Mendel learn from his experiments? 1)Alleles are different forms of a gene. 2)Alleles are either DOMINANT or Recessive. 3)Phenotype = physical characteristic shown is a result of at least 2 alleles.

13. Mendelian Genetics -- DOMINANT allele is the trait that ALWAYS shows up in the Phenotype. -- DOMINANT allele is ALWAYS represented by a CAPITAL letter (T= Tall) -- GENOTYPE = combination of alleles --Purebred Tall Pea Plants have GENOTYPE TT -- TT = HOMOZYGOUS DOMINANT -- HOMOZYGOUS = SAME --Both alleles inherited are DOMINANT or the same

14. Mendelian Genetics -- Recessive alleles are weak and hidden by dominant allele. -- Recessive alleles DO NOT show up in Phenotype UNLESS two are together*. -- Recessive alleles are represented by a lower case letter --Purebred short pea plants have GENOTYPE tt -- tt is HOMOZYGOUS Recessive. --Both alleles are Recessive or the same.

15. Mendelian Genetics So what was the GENOTYPE of the first generation Tall plants from Slide 9? Tall x Small = Tall Tt = HETEROZYGOUS Dominant -- HETEROZYGOUS = two alleles are NOT the same --One allele is DOMINANT the other Recessive -- HETERO = different -- Phenotype = DOMINANT trait ALWAYS shows up --Plants are tall.

16. Say What?

17. Do you know …. Gregor Mendel Heredity Trait Genes Cross Pollination Alleles GENOTYPE Phenotype Purebred HOMOZYGOUS HETEROZYGOUS DOMINANT Recessive How to write the GENOTYPES ? P generation F 1 generation F 2 generation

18. To be continued... Punnett Squares, Codominance, Probability, and Blood Typing.. OH MY!!!!