Variations in Heredity Section 5.2

Variations in Heredity Learning Goal: To explore traits that show incomplete and codominance. Success Criteria: explain the difference between complete dominance, incomplete dominance, and codominance explain how blood type is inherited and how blood type is used to determine compatibility for transfusions determine phenotypes and genotypes for traits that show incomplete and codominance

What Blood Type are You? Canadian Blood Types Type A Type B Type AB Type O Canadian Blood Types

Incomplete Dominance in some instances, neither of the alleles controlling the trait are dominant therefore a blending of traits occurs in heterozygotes e.g. snapdragon flowers genes that controls flower colour (C) has one allele for red (CR ) and one allele for white (CW) CRCR plant will produce red flowers CWCW plant will produce white flowers (CR CW) will produce pink flowers Note: in the F2 generation the phenotype ratio is the same as the genotype ratio (1:2:1)

Incomplete Dominance 1. What are the phenotypic and genotypic ratios for the F1 and F2 generation of a cross between and white and red snap dragon? 2. Indicate the ratios that would be expected if the following crosses are made: a) red x pink b) white x white c) pink x pink

Codominance again, both alleles for a trait may be equally dominant rather than blending, both alleles are expressed in the heterozygous individual e.g. shorthorn cattle a red bull (HRHR) crossed with a white cow (HWHW) will produce a roan calf (HRHW) that has intermingled white and red hair

Codominance 3. A red bull (without wings!!!) is crossed with a white cow. What is the F1 genotype and phenotype ratios?

Codominance & Dominance: Blood Types three blood type alleles: IA, IB , i results in the four major blood types: A, B, AB, and O alleles for blood types A and B are codominant blood type O is homozygous recessive

Codominance & Dominance: Blood Types Possible Genotypes Phenotypes ii Type O IAIB Type AB IAIA Type A IAi IBIB Type B IBi 1. human blood type both a codominant and dominant genetic trait

Codominance & Dominance: Blood Types A human blood group or “type” is a group of red blood cells that have the same antigen protein markers on the cell surface

Codominance & Dominance: Blood Types antibodies are proteins found in blood which recognize and attack particles foreign to the body (antigens) for example, someone with type A blood forms antibodies against the type B antigen (since it is foreign to this person) individuals who receive blood transfusions must receive blood that is compatible with their own giving this person blood containing the B antigen will cause a dangerous immune response

Codominance & Dominance: Blood Types type O blood is known as the “universal donor” type AB blood is the “universal recipient” Blood Type Antigens Present Antibodies Can receive blood from: Can donate blood to: A anti-B A and O A and AB B anti-A B and O B and AB AB both A and B no antibodies A, B, AB, O AB only O no antigens both anti-A and anti-B O only 1. in an emergency situation when there is no time to test the patient’s blood, type O blood may be used 2. 42% A, 9% B, 3% AB, 46% O

4. A woman with homozygous type A blood has a child with a man who is heterozygous B. What are the genotypes and phenotypes possibilities of the offspring?

5. A woman with A type blood marries a man with B type blood 5. A woman with A type blood marries a man with B type blood. They have a child with type O blood. The man says the child cannot be his. Is he correct? Show your work to prove you are right. If this child belongs to this father, what were the chances of having this child with type O blood.

Variations in Heredity Learning Goal: To explore traits that show incomplete and codominance. Success Criteria: explain the difference between complete dominance, incomplete dominance, and codominance explain how blood type is inherited and how blood type is used to determine compatibility for transfusions determine phenotypes and genotypes for traits that show incomplete and codominance

Blood Lab Inheritance Investigation

Homework complete worksheet “Incomplete and Codominance Practice Problems”