Multiple Alleles 2 2

Blood Type The ABO System

The Genetics of Blood Types Blood type is determined by 3 alleles. This is why it is an example of multiple alleles. Each individual can only inherit 2 of those alleles. (one from each parent) The blood type GENE has 3 possible alleles: A, B, and O each resulting from the type of protein on the red blood cell surface. The red blood cell protein is called an antigen 3

What alleles are dominant? What allele is recessive? 5) There are 6 possible combinations of these 3 alleles: Type A: ____, _____ Type B: ____, _____ Type AB: _____ Type O: _____ What alleles are dominant? A and B What allele is recessive? O Write it down!!!

Blood Type Shows 3 Types of Inheritance Patterns: 1) Complete dominance because… ) Co-dominance because… ) Multiple Alleles (the 3rd exception!) = _______ _______ because… A and B alleles are dominant, O allele is recessive. A and B alleles will hide/mask the O allele A and B alleles are BOTH dominant. AB blood type expresses BOTH A and B proteins (antigens) on red blood cells. Many alleles There are 3 possible alleles (A, B, and O) for blood type

AA, AO IAIA, IAi Multiple Alleles BB, BO IBIB, IBi OO ii IAIB AB Phenotype Genotypes Another way of writing the alleles Type of Inheritance Pattern Demonstrated A type blood B type blood O type blood AB type blood AA, AO IAIA, IAi Multiple Alleles BB, BO IBIB, IBi OO ii Codominance IAIB AB

4 Blood Types (Phenotypes) Antigens are PROTEINS on the surface of a red blood cell. A antigens only B antigens only A and B antigens No antigens 7

Make sure you have it right… proteins Blood type

Antibodies are specialized PROTEINS in the blood that attack bacteria and viruses that may infect our bodies When antibodes “stick” they form clumps. This is called AGGLUTINATION.

What antibodies are present in each blood type? Each blood type has antibodies opposite to it. For example, if a cell has A antigens, then it has anti-B antibodies. Because a B protein would be a foreign substance!

The shape of the antibody protein is SPECIFIC to the shape of the antigen protein!

Make sure you have it right… proteins proteins Blood type

What if you get the wrong blood type in a transfusion? Antibodies in your own blood will attack the foreign blood cell’s surface proteins/antigens. When antibodes “stick” to an antigen they form clumps. This is called AGGLUTINATION.

Can you figure these out? attack antigens (proteins) Can you figure these out?

So who can receive blood from who? Can receive from: So can you figure out the DONORS? Can only receive blood with matching antigens Can only donate if no antibodies are present

Make sure you have it right…

Interesting Information…

Solving Blood Type Problems 1) A mother is homozgyous for Type A blood. Her husband has Type O blood. What are the possible phenotypes of their children? What is the likelihood of the couple having a child with Type A blood? __________________ What is the likelihood of the couple having a child homozygous for Type A blood? _____________ Key: Type A: Type B: Type AB: Type O: Possible Phenotypes: Parent 1: Parent 2:

2) A mother is homozygous for Type B blood 2) A mother is homozygous for Type B blood. She has a child with Type AB blood. What are the possible genotypes of the father? Key: Type A: AA, AO Type B: BB, BO Type AB: AB Type O: O Father’s Genotype(s): Parent 1: Parent 2:

3) A mother has the genotype IAi and the father has the genotype IBi 3) A mother has the genotype IAi and the father has the genotype IBi. What are the chances they will have a child with Type O blood? Key: Type A: Type B: Type AB: Type O: Answer: Parent 1: Parent 2:

Quick Video to put it all together Amoeba Sisters! Multiple Alleles (ABO Blood Types) and Punnett Squares Complete the worksheet while you watch.

Practice Time! Work through the “Who’s Your Daddy??” practice sheet. Check your answers at the SSS!