Non-Mendelian Genetics Some traits don’t follow the simple dominant/recessive rules that Mendel first applied to genetics. Traits can be controlled by more than one gene. Some alleles are neither dominant nor recessive.

Incomplete Dominance Four O’Clock Plants One allele is not completely dominant over another. The heterozygous phenotype is a blending of the two homozygous phenotypes. Ex: RR (RED) x R’R’ (WHITE)= PINK (RR’) Four O’Clock Plants Curly x Straight= Wavy hair texture

CoDominance Two alleles are both expressed as a dominant phenotype. Coat color in cows RR: Red, WW: White, RW: Roan, white with red spots (NOT pink!)

Roan Animals Show Codominance

Multiple-Allele Series Codominance More than two choices of alleles are present for a trait ABO blood type has three alleles: ABO Blood types: If both A and B are present, type is AB Neither is recessive Individuals can be type A, B, AB, or O (recessive)

What is blood made up of? The red blood cells The white blood cells contain hemoglobin. Red blood cells transport O2 and CO2 to and from body tissues. The white blood cells fight infection. The platelets help the blood to clot The plasma Fluid which contains salts and various kinds of proteins.

Determining Blood Type                                                                                               (not actual shape or size of antigens)                                                                                               (not actual shape or size of antigens)                                                                                               (not actual shape or size of antigens) Determining Blood Type Protein molecules found on the surface of RBC’s and in the blood plasma determine the blood type of an individual. Antigens are located on the surface of the red blood cells Antibodies are in the blood plasma.

Human Blood Types

What are the different blood groups? Blood group A (IA, IA ), (IA, i) have A antigens on the surface of red blood cells and B antibodies in blood plasma. Blood group B (IB, IB ), (IB, i) have B antigens on the surface of red blood cells and A antibodies in blood plasma.

What are the different blood groups? Blood group AB (IA, IB ) have both A and B antigens on the surface of red blood cells and no A or B antibodies in blood plasma. Universal receivers Blood group O (i, i) have neither A or B antigens on the surface of red blood cells but have both A and B antibodies in blood plasma. Universal donors

Rh Factor Refers to another antigen on red blood cells Dominant trait is to have the antigen Rh+ Recessive trait is not to have it Rh- A person with Rh- blood will produce antibodies to Rh+ blood Can be a problem in pregnancy

Review Males have an X and a Y chromosome Females have two X chromosomes These chromosomes determine sex, so genes located on these chromosomes are known as sex-linked genes.

The X chromosome is much larger than the Y- it carries more genes than the Y chromosome. Disorders that are sex-linked are much more common in males, because they would only need 1 recessive allele to have the trait; rather than the two recessive alleles the females need.

Practice Problems EXAMPLES!! A woman who is heterozygous for normal vision marries a man who is colorblind. What are the chances of them having a son or daughter who is colorblind?

In fruit flies, the gene for eye color is sex-linked In fruit flies, the gene for eye color is sex-linked. The allele for red eyes if dominant, while the allele for white eyes is recessive. A white eyed male is mated with a heterozygous red-eyed female. Show the punnet square and list the genotypic and phenotypic ratios for this cross.