1. Chapter 12 When Heredity Rules are Different

2. Complex Patterns of Heredity Most traits are not simply dominant or recessive Incomplete dominance: when the phenotype of the heterozygous individual is in between those of the two homozygotes (a mixture)

3. Red flower color (RR) White flower color (rr) Pink colored flowers (Rr)

4. Codominace: when the alleles of both homozygotes (BB or WW) are expressed equally in the heterozygous individual – black chicken (BB) – white chicken (WW) – offspring will be checkered

5. Sex-linked traits: traits controlled by genes located on sex chromosomes – Sex chromosomes: 23 rd pair in humans that determine a person’s sex (X or Y) Females are XX, males are XY

6. X-linked disorders: generally passed on from mother to son – is found on the X chromosome Example: Down’s Syndrome (trisomy 21) colorblindness Y-linked disorders: only passed on from father to son Examples: excessive hair growth of the ears & male infertility

7. Colorblindness Tests Test Name: Ishihara Test Colorblind sees: yellow square Normal color: yellow square & faint brown circle Colorblind sees: the number 17 Normal Color sees: the number 15

8. Polygenic inheritance: when one trait is controlled by many genes. Examples: height, eye color, skin color, & blood type

9. Changes in Chromosomal Numbers Humans have 23 pairs of chromosomes (46 total); more or less = disorder Autosomes: a non-sex chromosome – Known as chromosomes 1-22

11. 8 Environmental Factors That Can Also Influence Gene Expression 1. temperature 2. light 3. nutrition 4. chemicals 5. infectious agents 6. hormones 7. structural differences 8. age *** know examples***

12. Chapter 12: Patterns of Heredity & Human Genetics Mendelian Inheritance of Human Traits

13. Making a Pedigree When genetic inheritance is represented by a picture, this is called a pedigree. – It is a diagram made of symbols that identify three things: 1. Male or female 2. Individuals affected by the trait being studied 3. Family relationships

14. S ymbols of a pedigree: ***need to know*** Carrier – heterozygous individual

15. Constructing and Reading a pedigree ***Roman Numerals (I, II, III) refers to the generations.*** *Arabic numbers refers to individuals. (1, 2, 3, 4, 5, …) 321456 1 1 2 2 345 I. III. II.

16. Reading the pedigree… How many generations are there? How many children did II-1 have? II-7? How are III-5 and III-2 related? Who is III-2 in reference to I-2 ? 32145 61 1 2 2 345 I. III. II. 7

17. Simple Recessive Heredity Most genetic disorders are caused by recessive alleles. This means the disorder is inherited when both parents have a recessive allele. Ex: Cystic Fibrosis (CF), Tay-Sachs Disease

18. Pedigree for Cystic Fibrosis

19. Pedigree for Tay-Sachs

20. Simple Dominant Heredity Dominant disorders: Only one dominant allele has to be inherited from either parent. Simple Dominant Traits –1. cleft chin –2. unattached earlobes –3. almond shaped eyes –EX: Huntington’s Disease

21. Is it Dominant or Recessive… Dominant, only one parent has the disorder. 3 214 5 6 1 1 2 23 4 3 I. III. II.

22. Is it Dominant or Recessive… Recessive, neither parent has the disorder. Both are heterozygous. 3 214 5 6 1 1 2 23 4 3 I. III. II.