HEREDITY

1. HEREDITY

2. INCOMPLETE DOMINANCE • With incomplete dominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype that is a blending of the parental traits.

3. INCOMPLETE DOMINANCE • When the phenotype of the heterozygous is intermediate between the two homozygous • Neither allele is dominant/recessive over the other. Neither allele will express itself---therefore NO capital or lower case letters

4. EX: Snapdragon flowers. Red flowers White flowers Pink Flowers When working these problems it becomes essential to make a key Red (RR) White (WW) Pink (RW) INCOMPLETE DOMINANCE

5. INCOMPLETE DOMINANCE • Cross a Red Snapdragon flower with a White Snapdragon flower. • Set up the Punnett Square and give me both pheno and geno Ratios.

6. INCOMPLETE DOMINANCE

7. Phenotypic Ratio 100% Pink Genotypic Ratio 100% RW INCOMPLETE DOMINANCE

8. INCOMPLETE DOMINANCE • You cross two pink flowers and give me both phenotypic and genotypic ratios.

10. CO-DOMINANT ALLELES • Where both alleles express themselves fully. • With Co-dominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype. This third phenotype has BOTH parental traits expressed.

11. CO-DOMINANT ALLELES • This is most commonly seen in chickens. Cross a black chicken with a white chicken you get what is called a speckled chicken • NOT GRAY…but both alleles (black and white) fully express themselves so the chicken has both types of feathers.

13. CO-DOMINANT ALLELES • White cow crossed with a Red Bull

14. CO-DOMINANT ALLELES Roan Cow…. Roan refers to cows that have red coats with white blotches.

15. CO-DOMINANT ALLELES A white horse crossed with a black stallion

16. CO-DOMINANT ALLELES A gray horse…but upon closer inspection it has hairs that are both black and hairs that are white.

17. POLYGENIC TRAITS • More than one allele pair controls a single trait— • Ex: Skin Color—Several different allele pairs attribute to the overall phenotype—Tone, distribution, etc

18. MULTIPLE ALLELES • A population might have more than two alleles for a given gene. • In this case you have to think of a gene as a segment of your DNA that controls a trait. • You have more than 2 choices for an allele for each trait. • Even if more than two alleles exist in a population, any given individual can have no more than two of them.

19. MULTIPLE ALLELES • Ex: Blood type, Rabbit Fur, Labrador Retriever Coat Color

20. MULTIPLE ALLELES • In Labs, coat color is determined by one gene with four different alleles. Five different colors result from a combination of these alleles.

21. Phenotype Possible Genotypes BBEE BbEE BBEe BbEe BBeeBbeebbee bbEEbbEe

22. Multiple Alleles- Blood Type

23. Multiple Alleles- Blood Type

24. Multiple Alleles-Rabbit Fur • Coat color in rabbits is determined by a single allele pair that has at least four different alleles. • Full(C), Chinchilla (Ch), Himalayan (h), Albino (c)

25. We already know that each human has 46 chromosomes which means they have 23 homologous pairs. The 23rd Pair is different. It determines the sex of the individual. SEX CHROMOSOMES

26. Homologous Pairs 1-22 are called Autosomes The 23 pair often called the Sex Chromosome. SEX CHROMOSOMES

27. FEMALE SEX CHROMSOMES • Female 23rd Chromosome is represented by XX.

28. MALE SEX CHROMSOMES • The 23 Chromosome on the male is represented with a XY.

30. SEX-LINKED TRAITS • Genes that are carried by either sex chromosome are said to be Sex-linked Traits.

31. SEX-LINKED TRAITS • Scientist discovered this linkage when studying fruit flies (Drosophilia). Through many experiments scientist soon concluded eye color of these flies were determined by the sex chromosome.

32. Often an allele for a trait can be found on the X but not on the Y chromosome. The Y chromosome on the male carries little or NO genetic information. SEX-LINKED TRAITS

33. SEX-LINKED TRAITS • WHEN WORKING ANY SEX-LINKED TRAIT YOU MUST ALWAYS WRITE IT OUT…… • XX x XY • You still have dominant and recessive alleles.

34. SEX-LINKED TRAITS • Eye color in fruit flies is a sex-linked trait where Red eyes is dominant over White eyes. (This trait is carried on the X chromosome) • Cross a heterozygous Red eyed female with a red eyed male.

35. SEX-LINKED TRAITSPractice Problems • Cross a heterozygous Red eyed female with a red eyed male. • Cross a homozygous Red eyed female with a white eyed male. • Allow the F1 generation male/female to cross. • Show me Cross, Punnett Square, and Phenotypic and Genotypic Ratio

36. Most sex-linked traits are carried on the X chromosome. Therefore the female will carry two and the male will only carry one. However, some sex-linked traits are carried on the Y…but only a few!! SEX-LINKED TRAITS

38. SEX-LINKED TRAITS • Colorblindness • Hemophilia • Duchenne Muscular Dystrophy • Fragile X Syndrom

41. SEX-INFLUENCED TRAITS • (NOT located on X or Y chromosome)- found in both sexes but expressed differently. • Baldness-caused by autosomal allele that is dominant in men due to the presence of testosterone. It is recessive trait in women. • Index finger length- Dom/fem Rec/Mal

42. SEX-LIMITED TRAITS • Sex-limited traits are autosomal traits that are expressed in only one sex (In normal conditions) • Ex: Breast, Beards, Breast milk.

43. TESTCROSS • Testcross- one way to determine the genotype of an unknown genotype is to cross it with a known genotype (usually recessive)

44. TESTCROSS • A breeder is considering using this dog to produce offspring. However the owner is unsure if the dog is a possible carrier of a common hearing problem. She knows that he has normal hearing. What can she do?

45. A carrier is a heterozygous individual. They do NOT have the trait but do have the possibility to pass it to their offspring. Dd Carrier

46. When performing a test cross you would cross the unknown genotype with a known…usually a homozygous recessive. Many breeders will rely on a testcross to determine if they are dealing with a pure breed or a hybrid. TESTCROSS

48. PEDIGREE • A graphic representation of an individuals family tree.