1. So far, weve discussed Simple Inheritance & Punnett Squares… But, of course, Genetics is much more complicated than that. Genetics Beyond Mendel

2. More Complex than Simple Inheritance Degrees of Dominance Patterns of dominance often go beyond simple dominant or recessive traits. Patterns of dominance often go beyond simple dominant or recessive traits. Dominance had degrees. It is not always complete. Dominance had degrees. It is not always complete. Incomplete dominance: Incomplete dominance: F1 generations appearance between the phenotypes of the 2 parents. Ex: snapdragons Incomplete Dominance

3. More Complex than Simple Inheritance Co-Dominance & Multiple Alleles Multiple alleles: more than 2 possible alleles for a gene. Multiple alleles: more than 2 possible alleles for a gene. Ex: human blood types (ABO) Co-dominance: two alleles affect the phenotype in separate, distinguishable ways. Co-dominance: two alleles affect the phenotype in separate, distinguishable ways. Ex: AB Blood Type Ex: AB Blood Type Codominance

4. A little bit of immunology…. Antigens Molecules that trigger a specific immune response. Molecules that trigger a specific immune response. Include components of bacterial cell Include components of bacterial cell walls, plus proteins of viruses, fungi, protozoa. Food, pollen, and dust can also contain antigenic particles Food, pollen, and dust can also contain antigenic particles How our body tells the difference between self and non- self. How our body tells the difference between self and non- self. Enter the body by various methods Enter the body by various methods –Through breaks in the skin and mucous membranes –Direct injection, as with a bite or needle –Through organ transplants and skin grafts Multiple Alleles & Co-dominance: Immunology of Blood Types

5. A little bit of immunology…. Antibodies Also called immunoglobulins (Ig) Also called immunoglobulins (Ig) Proteinaceous molecules that bind antigens Proteinaceous molecules that bind antigens Considered part of the humoral immune response since bodily fluids such as lymph and blood were once called humors Considered part of the humoral immune response since bodily fluids such as lymph and blood were once called humors Can act as labels to identify Can act as labels to identify antigens for elimination from body. antigens for elimination from body. FYI Some work as antitoxins i.e. they block toxins for e.g. those causing diphtheria and tetanus FYI Some attach to bacterial flagella making them less active and easier for phagocytes to engulf FYI Some cause agglutination (clumping together) of bacteria making them less likely to spread Multiple Alleles & Co-dominance: Immunology of Blood Types

6. Antigen on viral surface Antibody Multiple Alleles & Co-dominance: Immunology of Blood Types

7. OK, now were ready to talk about blood… Blood Type : ABO – 1 gene, 3 alleles (I A, I B, i) A & B are co-dominant (both expressed if both present) A & B are co-dominant (both expressed if both present) Type A = A type antigen on surface of blood cell. Genotype is either: I A I A or I A i) Type B = B type antigen on surface of blood cell. Genotype is either: I B I B or I B i) Type AB = Both antigens on surface of blood cell. Genotype is only: I A I B Type O = No antigen on surface of blood cell. Recessive genotype: i i Type O = No antigen on surface of blood cell. Recessive genotype: i i Whatever blood type you are, you make antibodies against the other types of antigens. Whatever blood type you are, you make antibodies against the other types of antigens. –Best position to be in is AB. You can take anyones blood. –O is universal donor, because no antigen on surface of cell. Multiple Alleles & Co-dominance: Immunology of Blood Types

8. Monohybrid Cross Parental Generation Mendel determined that, in pea plants, tall height (T) is dominant to dwarf (t). This means that heterozygous plants (Tt) are tall. The allele for tall (T) completely masks the allele for dwarf (t) in producing the phenotype. This allele relationship is called COMPLETE DOMINANCE. Mendel determined that, in pea plants, tall height (T) is dominant to dwarf (t). This means that heterozygous plants (Tt) are tall. The allele for tall (T) completely masks the allele for dwarf (t) in producing the phenotype. This allele relationship is called COMPLETE DOMINANCE. You can use a PUNNETT SQUARE to predict the outcome of crossing a homozygous tall plant (TT) with a dwarf plant (tt). The resulting offspring are called the F1 generation. You can use a PUNNETT SQUARE to predict the outcome of crossing a homozygous tall plant (TT) with a dwarf plant (tt). The resulting offspring are called the F1 generation. Cross the two parents, homozygous dominant tall plant (TT) and recessive dwarf plant (tt). Parent (TT) Parent (TT) Parent (tt) F1 Generation F1 Generation Note: Always put the dominant allele (T) first when writing a genotype (Example - Tt) What is the expected genotype of the F1 generation? 4:0 Describe the expected phenotype(s) of the F1 generation: All Tall Plants TT t t TtTt TtTtTtTt TtTt

9. Monohybrid Cross F2 Generation Cross two members of the F1 generation: Parent (Tt) Parent (Tt) Parent (Tt) F2 Generation F2 Generation What is the expected genotype ratio of the F2 generation? 1:2:1 What is the expected genotype ratio of the F2 generation? 1:2:1 What is the expected phenotype ratio of the F2 generation: What is the expected phenotype ratio of the F2 generation: 3 Tall, 1 short T T t t TT TtTt TtTt tt

10. Incomplete Dominance Parental Generation Sometimes, a cross between two individuals, each pure for a particular characteristic, results in partial expression of both traits in the F1 phenotype. One gene incompletely masks the other in the heterozygote. Sometimes, a cross between two individuals, each pure for a particular characteristic, results in partial expression of both traits in the F1 phenotype. One gene incompletely masks the other in the heterozygote. Complete the following Punnett squares using the information. Since dominance is not operating, a slight modification of gene symbols is used. We will use the letter C to represent color in snapdragons. CR will represent the allele for red color and CW will represent the allele for white color. The hybrid of a red and a white snapdragon is pink, so would be represented as CR CW. Complete the following Punnett squares using the information. Since dominance is not operating, a slight modification of gene symbols is used. We will use the letter C to represent color in snapdragons. CR will represent the allele for red color and CW will represent the allele for white color. The hybrid of a red and a white snapdragon is pink, so would be represented as CR CW. Use this Punnett square to reveal the genotype of the F1 generation, where the parent plants consist of a red and a white snapdragon plant. Parent (C R C R ) Parent (C R C R ) Parent (C W C W ) F1 Generation F1 Generation What is the expected genotype of the F1 generation? 4 : 0 What is the expected genotype of the F1 generation? 4 : 0 Describe the expected phenotype(s) of the F1 generation: All Pink Describe the expected phenotype(s) of the F1 generation: All Pink CRCR CWCW CWCW CRCR CWCRCWCR CWCRCWCR CWCRCWCR CWCRCWCR

11. Incomplete Dominance Parental Generation F2 Next, cross two of these F1 snapdragon plants to obtain the theoretical or expected phenotypic and genotypic rations of the F2 generation. Parent ( C R C W ) Parent ( C R C W ) Parent ( C W C R ) F2 Generation F2 Generation What is the expected genotype of the F2 generation? 2:1:1 What is the expected genotype of the F2 generation? 2:1:1 Describe the expected phenotype(s) of the F2 generation: 2 pink, 1 Red, 1 White Describe the expected phenotype(s) of the F2 generation: 2 pink, 1 Red, 1 White CWCW CWCW CRCR CRCR CW CRCW CR CW CRCW CR CRCR CRCR C W