Non Mendelian Traits (Mendelian Exceptions)

Incomplete Dominance A cross between organisms with two different phenotypes Ex: Red (RR) x White (WW) Produce offspring with a third phenotype that is a blending of the parental traits - Ex: Pink (RW) red pink white

Incomplete Dominance EX: If a homozygous red flowered snap dragon plant (RR) is crossed with a homozygous white flowered snap dragon plant (WW), all of the offspring will have pink flowers. RED flower x WHITE flower  PINK flower RW RW RW RW

Incomplete Dominance RR BB RB In another flower, if red ____ and blue ____ flowers are crossed, they produce a 3rd purple ____ flower - What would be the genotype ratio and phenotype ratio if you crossed two purple flowers? BB RB http://www.gwu.edu/~darwin/BiSc150/One/rose.GIF

Incomplete Dominance Cross of two purple flowers ____ X ____ What are gamete possibilities? RB X RB genotype ratio 1RR : 2RB : 1BB phenotype ratio 1red : 2 purple : 1 blue Can you have a heterozygous red or hybrid blue flower? ___ RB RB R B RR RB R red purple http://www.gwu.edu/~darwin/BiSc150/One/rose.GIF BB RB B purple blue no

In Labrador retrievers, yellow is incompletely dominant to black In Labrador retrievers, yellow is incompletely dominant to black. The heterozygous phenotype is chocolate. Cross a yellow lab with a chocolate lab. - Find gametes - Find genotype percent - Find phenotype percent

Codominance A cross between organisms with two different phenotypes - Ex: Red x White Produce offspring with a third phenotype that displays BOTH traits at the same time - Ex: Red and White Striped

Codominance EX: If a homozygous red flowered snap dragon plant (RR) is crossed with a homozygous white flowered snap dragon plant (WW), all of the offspring will have Red and white flowers. - RED flower x WHITE flower  RED & WHITE flower http://www.ccs.k12.in.us/chsteachers/Amayhew/Biology%20Notes/beyond%20dominance%20notes_files/image004.jpg

Codominance Andalusian chickens show patterns of codominance. If you cross a black (BB) chicken with a white (WW) chicken You get a black & white speckled (BW) chicken

Human Codominance Sickle-Cell Anemia An individual who is heterozygous for sickle-cell alleles will express BOTH normal and abnormal shaped blood cells The oxygen carrying protein hemoglobin differs by one amino acid this causes regular disk shape to be changed to abnormal half moon or sickle shaped. Abnormally shaped blood cells slow blood flow, block vessels, and result in tissue damage and pain. Heterozygous individuals are said to have the sickle-cell trait because they show signs of sickle-cell related disorders if the availability of oxygen is reduced. Normal red blood cell Sickle cell

Human Codominance Blood Types Blood type is determined by multiple alleles. This means there are more than two types of alleles possible that can make up a paring. Allele A: red blood cells produce A antigens (protein) on the outside of the cell Allele is expressed IA or A because it is dominant Allele B: red blood cells produce B antigens (protein) on the outside of the cell Allele is expressed IB or B because it is dominant Allele O: red blood cells will NOT produce an antigen (protein) Allele is expressed I or O because it is recessive

Human Codominance Blood Types Determining Blood types is necessary before you receive a blood transfusion because incompatible red blood cells clump together or clot causing death. Your immune system or antibodies recognizes the red blood cells belonging to you. If cells with a different type of antigen enter your body your immune system will attack them

Multiple Alleles ______ different phenotype blood groups: A, B, O, & AB Are produced by ______ different alleles: A, B, and O FILL in your chart & answer the following questions Which ones are homozygous? Which ones are heterozygous? Which one is codominance? Four Phenotype All Genotypes Possible Type A (Dominant) IAIA (AA), IAi (AO) Type B (Dominant) IBIB (BB), IBi (BO) Type AB (Codominant) IAIB (AB) Type O (recessive) ii (OO) three

Will the following cause death? Can a person with type A blood receive type O blood? Can a person with type B blood receive type AB blood?

Multiple Alleles Example problems: Blood type crosses