Genetics and Inherited Traits: Exploring the Science of Heredity

1. Genetics

2. Think about this…. • “My parents have brown eyes, why are mine blue?” • “My brother is tall. Why am I short?” • “Why does my sister have blonde hair while mine is brown?”

3. Are these inherited traits? Your eye color Your hair color and texture Your height

4. Are these inherited traits? Your personality Your musical, athletic, and artistic abilities

5. Gregor Mendel • Born in 1822 in Austria • Studied the garden pea plant to determine genetics Father of Genetics

6. Gregor Mendel • Heredity – the passing on of characteristics from parents to offspring • Characteristics that are inherited are called traits

7. Gregor Mendel • Mendel studied only 1 trait at a time to control the variable • The tall plants that he worked with had been tall for many generation and had always produced tall offspring • This is calledtrue breeding

8. Mendel’s Monohybrid Crosses • Mono = one • Ahybrid is the offspring of parents that have different forms of a trait • Such as tall and short

9. P generation - parents The F1 generation (hybrids) were all purple – self pollinated F2 generation had a ratio of 3:1 3 purple 1 white F stands for filial – son or daughter Mendel’s Monohybrid Crosses

10. The dominant trait is the trait that is observed The recessive trait is the trait that ‘disappears’ What trait is dominant? The rule of dominance

11. The rule of dominance • Which is dominant and which is recessive? • TT Tt tt • BB bb Bb • ww WW Ww • HH hh Hh

12. Phenotypes and Genotypes • The way an organism looks or behaves is called its phenotype

13. The allele combination an organism contains is its genotype represented as TT for tallness Any plant that is tall has a genotype either TT of Tt Phenotypes and Genotypes

14. Homo: same Two alleles for the trait are the same (TT or tt) Which ones are homozygous? Homozygous

15. Hetero = different Two alleles differ from one another (Tt) Heterozygous

16. A a AA A Aa a Aa aa Monohybrid crosses • a cross that shows the possible offspring for one trait Punnett Square Aa x Aa A: White fur a: Brown fur Genotypic Ratio: 1:2:1 Phenotype: 3 white:1 brown

17. A A A a Practice! Cross a HOMOZYGOUS dominant female rabbit with a HETEROZYGOUS male rabbit using the same trait. A: White fur a: Brown Fur What is the genotypic ratio? What is the phenotypic ratio?

18. A A A a Practice! Cross a HOMOZYGOUS dominant female rabbit with a HETEROZYGOUS male rabbit using the same trait. What is the genotypic ratio? AA AA 2 = AA 2 = Aa 2:2 or 50% What is the phenotypic ratio? Aa Aa 4 white fur

19. Practice!! • Cross a female (Tt) with a male (Tt) using the traits: T: tall t: short T t T t

20. Practice!! • Cross a female (Tt) with a male (Tt) using the traits: T: tall t: short T t T t

21. Now its time for more practice…

22. Dihybrid crosses • two traits calculated :RrYy x RrYy

23. BR Br bR br BR BBRR BBRr BbRR BbRr Br BBRr BBrr BbRr Bbrr bR BbRR BbRr bbRR bbRr br BbRr Bbrr bbRr bbrr Dihybrid Crosses:a cross that shows the possible offspring for two traits BbRr x BbRr Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth BbRr x BbRr Phenotypic Ratio: 9:3:3:1

24. More Complex Patterns of Heredity • Codominance/ Incomplete dominance • Multiple Alleles • Sex-Linked Traits

25. Codominance:two dominant alleles are expressed at the same time CRCR CWCW CRCW

26. Codominance • Sickle-Cell Anemia is another codominant trait. NA NA NSNA NSNA NS NA=Normal RBC NANA NANA NS=Sickle Cell RBC NA

27. Multiple Alleles:traits with more than 2 alleles • Blood type has 3 alleles: A, B, O • A and B are codominant over O • O is recessive

28. What are Sex-Linked Traits? Traits that are located on one of the sex chromosomes (XY) Hemophilia: Failure of blood to clot Alix and Nicholas II Muscular Dystrophy: wasting away of muscles

29. Can I inherit a sex-linked disease? Mothers (XX) can pass disorders to both sons (XY) and daughters (XX) Fathers (XY) can only pass disorders to daughters (XX) Most disorders are carried on the X chromosome, so males are more likely to inherit them.

30. How can I tell if I have a genetic disorder? • Karyotypes are a “map” of all 46 (23 pair) of chromosomes.

31. What’s wrong with this Karyotype? Is this a male or a female?

32. What’s wrong with this Karyotype? Is this a male or a female?

33. Down Syndrome Down syndrome occurs because of the presence of an extra 21st chromosome. Down syndrome is also called trisomy 21 Physical Traits • Short stature. A child often grows slowly and, as an adult, is shorter than average. • A short, wide neck with excess fat and skin • Small, low-set ears.

34. chromosome abnormality that affects only men born with at least one extra X chromosome. The male with Klinefelter Syndrome will be born with 47 chromosomes in each cell, rather than the normal number of 46. Klinefelter Syndrome is also called 47 X-X-Y syndrome. An infant with Kleinnfelter's Syndrome appears normal at birth, but the defect usually becomes apparent in puberty when secondary sexual characteristics fail to develop, and testicular changes occur that eventually result in infertility in the majority of those affected. Klinefelter Syndrome

35. Trisomy 13 Most cases of Patau syndrome are not inherited, but occur as random events during the formation of reproductive cells (eggs and sperm). Symptoms: Mental & motor challenged polydactyly (extra digits) Heart defects Cleft palate Spinal defects Patau syndrome