1. Basic Mendelian Genetics What lovely things we pass onto our children!

2. Mendel’s Laws Law 1: Law of Unit Characteristics –Inherited traits are controlled by “factors” which occur in “pairs”.  Factors = __________  Pairs = __________ Law 2: Law of Dominance –One allele hides another allele in a heterozygote  Stronger allele = _____________  Weaker allele = _____________

3. Mendel’s Laws Continued Law 3: Law of Segregation –Alleles of a gene are separated during gamete formation  Each cell only gets 1 allele for a gene A a Bb

4. Mendel’s Laws Continued Law 4: Law of Independent Assortment of Alleles –When alleles separate during meiosis, they do so independently of alleles of other genes  Placement of alleles is random  Not influenced by other genes A A B B a a b b

5. Mendel’s Laws Continued Law 5: Law of gene pricing –Lee genes are usually less expensive than Levi’s, except when Levi’s are on sale

6. Life Beyond the Law of Dominance Not all traits are governed by the law of dominance Incomplete Dominance –Neither allele is completely dominant over the other in the heterozygote  Blending/Mixing Ex) Snap dragons WW – White flowers RR – Red Flowers RW – Pink Flowers

7. Incomplete Dominance

8. Life Beyond the Law of Dominance Codominance –Both genes express themselves FULLY at the same time Example: Roan cattle RR = Red Hair WW = White Hair RW = Roan (both red + white) Example 2: Blood type in humans (AB)

9. Life Beyond the Law of Dominance Multiple Alleles –A gene possessing more than 2 alleles Example: Blood types  Blood types differ in antigens found on RBC’s AA – Homozygous AType A BB – Homozygous BType B OO – Homozygous OType O AO – Heterozygous AType A BO – Heterozygous BType B AB – Heterozygous AB Type AB

10. Life Beyond the Law of Dominance Polygenic Inheritance –When a trait is controlled by more than 2 genes Example: Eye color (3 genes)  Amount of pigment  Location of pigment  Tone of pigment

12. Cowboys denied home field by Eagles

13. A Review of Mendelian Genetics 1)Neither allele is dominanta) Complete Dominance 2)More than 2 allelesb) Codominance 3)Both alleles are dominantc) Incomplete dominance 4)Many genes code for 1 traitd) Multiple alleles 5)One allele is dominante) Polygenic inheritance