Multiple Allele traits

Multiple allele traits These are traits for which more than 2 alleles can be present in a population. Individuals only inherit 2 traits (one from each parent). e.g. hair colour in rabbits (see p. 245 of your textbook)

Hair colour in rabbits There are 4 different alleles for the colour of rabbit fur, and each has a different degree of dominance.

Human blood type There are 3 different alleles present that determine the ABO blood typing in humans – A, B and O. Of these alleles, A and B are co-dominant, and both A and B are dominant to O.

Human blood type These A and B alleles code for the presence of different protein molecules (antigens) that are found on the surface of red blood cells, and help the body to identify these cells. Those with type O alleles does not code for any surface alleles.

Human blood type

Human blood type Each individual inherits 2 of the possible 3 alleles that are found in the population. There are 6 possible genotypes, but only 4 phenotypes for human blood groups

Human blood type Genotype Phenotype AA (IA IA) Type A blood AO (IA i) BB (IB IB) Type B blood BO (IB i) AB (IA IB) Type AB blood OO (ii) Type O blood

Human blood type – example A man with type AB blood has children with a woman who has type O blood. Give the genotypic and phenotypic ratios for the potential offspring they can produce. Man – AB or IAIB Woman – OO or ii A or IA B or IB O or i AO or IAi BO or IBi O or i Genotypic ratio : 1 AO : 1 BO Phenotypic ratio: 1 type A : 1 type B

Human blood type Knowledge of the type of antigens on our red blood cells is important in ensuring that we have the correct type of blood administered to us, in the case that we should need a blood transfusion. Your body will reject some blood types that do not match to our own. This is because some blood types have antibodies to the other blood types floating in the plasma.

Antibodies Antibodies are proteins that bond to a specific antigen to remove the foreign antigens from the circulation. A person with type A blood antigens would carry type B antibodies. A person with type B blood antigen would carry type A antibodies

Agglutination Agglutination or clumping of the blood in the blood vessels will occur when a blood antibody meets the blood antigen that fits it. If a person with type A blood is given type B blood accidentally, this process will occur

Rhesus factor A person may be told that they have type A+ or B- blood. The positive or negative aspect of their blood type refers to another surface blood protein known as rhesus factor. Rhesus factor is inherited following simple dominant/recessive inheritance. Having the factor is dominant (+), not having it is recessive (-).

Universal donor and receiver Universal donor is a person who can donate blood to anyone, and it will not be rejected. Their red blood cells should have NO surface proteins– Type O Rh- Universal recipient is a person who can receive blood from anyone and it will not be rejected. Their red blood cells should have ALL surface proteins – Type AB Rh +

Blood type dihybrid A person with type AB Rh+ blood who is heterozygous for rhesus has children with a person who has type O- blood. Determine the possible genotypes and phenotypes of their children. ABRr x OOrr A R A r B R B r O r AORr AOrr BORr BOrr