Jumpstart 12/3

A pea plant with the genotype TtWW is crossed with a pea plant with the genotype ttWw. How many different genotypes can be expressed in the offspring? _____

(SHOW ALL WORK!)

a. 1 b. 2 c. 3 d. 4

How many different phenotypes? ______

Blood Types

Multiple Alleles More than two forms of a gene that code for a

trait (more than 2 letters to represent the trait) Phenotype is still determined by a pair of

alleles! The gene pool simply contains more than two.

These alleles can be expressed in various ways: Complete dominanceCo-dominance Incomplete dominance

Multiple Alleles: Human Blood TypeBlood Type is Coded by Multiple Alleles A, B, and O.

*A and B are co-dominant.*A and B are completely dominant over O.

PhenotypesType AType AType BType B

Type ABType O

GenotypesAAAOBBBOABOO

*The genes cause the production of a cell surface protein A or B.Type O cells have neither protein, so Type O individuals are Universal DONORS. Which individuals are Universal RECEPIENTS (have both proteins)?

Blood Types…

Blood from the donor to the recipient must be compatible.

The problem occurs when the protein (antigen) outer layer of the RBC of a donor becomes coagulated (clumped) with the plasma proteins (antibodies) of the recipient.

Blood Types… There are four different types of blood

A, B, AB, O

They are determined by the protein (antigen) found on the RBC

Type A, has protein (antigen) A on the RBC Type B, has protein (antigen) B on the RBC Type AB, has both protein (antigen) A and B on

the RBC Type O, has neither protein (antigen) on the

RBC

Type A would have B agglutinins (antibody) in the plasma.

Type B would have A agglutinins (antibody) in the plasma.

Type AB would not have agglutinins (antibody) in the plasma.

Type O would have A and B agglutinins (antibody) in the plasma.

Type O is the universal donor, since it does not have antigens (proteins) on the surface of the RBC’s It can be given to anyone and no clumping will

occur! Type AB is the universal recipient, since it does

not have agglutinins (antibody) in its plasma.They can receive any blood since they have no

antibodies!

Multiple Alleles

Many genes are present in 3 or more versions (alleles) – this is known as multiple alleles.

The human ABO blood group is determined by three alleles (IA, IB, and i) of a single gene.

The AB phenotype (genotype IA IB) is an

example of codominance!!

Codominance

The human ABO blood group illustrates another genetic

phenomenon – codominance.

Codominance occurs when the phenotype associated with each allele is expressed in the

heterozygote – both are expressed!

Problem 1

1. In humans, the blood types A, B, AB and O are determined by three alleles. A man who has AB blood marries a woman with O blood. What are the genotypes and phenotypes of the offspring?

Problem 2

2. A man who is heterozygous type A marries a woman who is heterozygous type B. What percentage of their offspring will be Type 0?

Problem 3

3. If a man with blood type B, one of whose parents had blood type O, marries a woman with blood type AB. What percentage of their children should have blood type B?

Problem 4

4. A man with type O blood and a woman with type AB blood get married. One of their children needs an operation. This child has type B blood. Can the child safely receive a blood transfusion from either parent? If not, why?

TOTD -Multiple Alleles:Who’s the baby daddy?

You have been hired by Maury Povich to work for a show he is Having on

Baby A - Type O Blood Baby B - Type B Blood

Smiths - Types O and AB Jones - Types A and B

1

Baby C - Type AB Blood Baby D - Type A Blood2

Squares -Types AB and AB Angles -Types AB and O