MULTIPLE ALLELES

Multiple alleles are three or more alleles for a particular gene.An example of multiple alleles is the ABO blood group system in humans.Blood type is controlled by three alleles - A, B and O.Allele Ois always recessive.AandBare codominant.TheABOblood type is determined by the presence or absence of twoantigens, A and B. Allele O does not code for an antigen.Antigen isany substance that induces the immune system to produce antibodies against it. ACTIVITY 3Choose the letter of the correct answer. 1. To which blood type can B blood donate? Type B only Type B and AB Type AB and O All blood types 2. What blood type can be received by a person whose blood type is AB? A B AB O 3. Which blood type is the universal acceptor? A B AB O 4. Which of the following is NOT TRUE to a person with Type O blood? He can be a donor to a Type A blood He can be a donor to a Type B blood He can be a donor to a Type AB blood He can receive any blood type 5. Which of the following is correctly stated? O is dominant over A. B is dominant over A. O is always recessive. A is dominant over B. A man with AB blood is married to a woman with AB blood. Show the Punnett square for this. A A B AA AB BB AB B 6. Refer to the problem above. What are the parents' genotypes? AB x AB AA x BB AO x BO AB x OO If they have eight children, how many of them could possibly have type AB blood? 8 6 4 2