SR.GENETICS.6B

BIOLOGY CURRICULUM 2006

ALTERNATIVE PATTERNS OF INHERITANCE PART I:

CODOMINANCE:

HUMAN BLOOD TYPES

1.  Define CO-DOMINANCE:

2.  Write two facts about blood type:

3.  Which allele is recessive? ______

4.  Write the possible genotypes and antigens produced for each of the four blood phenotypes.

Phenotype / Genotype(s) / Antigen(s) Produced
A
B
AB
O

5.  If a person with AO blood has children with a person who has type AB blood, what is the probability that they will have children with type B blood? Draw a Punnett square to prove your answer, and express the probability as a ratio or a percent. ______

6.  Because blood type is inherited, it is used as evidence in paternity cases. A mother is blood type A (that is her phenotype). Her child is type O. Three men claim paternity. Use what you have learned about blood type and Punnett squares to solve the problem.

a.  Baby’s genotype ______

b.  What does the mother’s genotype have to be? ______

c.  Why? ______

d.  What allele did the baby get from its mother? ______

e.  What allele did it get from its father? ______

f.  Use Punnett squares to show whether the following men are possible fathers. Use the same mother in all three Punnett squares. Circle the most likely father.

Male 1: type AB Male 2: type A Male 3: type O

ALTERNATIVE PATTERNS OF INHERITANCE PART II:

SEX-LINKED TRAITS:

HEMOPHILIA

1.  Define SEX-LINKED TRAITS:

2.  Write two facts about hemophilia:

3.  Complete the symbols for the Hemophilia alleles: dominant X recessive X

4.  Fill in the blanks. Sons inherit the ____ chromosome from their mother and the ___ chromosome from their father. Daughters inherit the ___ chromosome from their mother and the ___ chromosome from father.

Genotype / Phenotype
Sex
(M or F) / Hemophilia?
(Y or N)
XH XH
Xh Xh
XH Y
Xh Y
XH Xh

1.  Fill in the phenotype for each genotype.

2.  Circle the carrier genotype from the list of genotypes in the chart.

3.  Use a Punnett square to determine the possible offspring that a carrier and a hemophiliac male will have.

a.  What percent chance do they have of getting a daughter with hemophilia? ______

b.  A son with hemophilia? ______

4.  Draw a Punnett square for each example. You may need more than one square for each.

745

SR.GENETICS.6B

BIOLOGY CURRICULUM 2006

a.  Matings that will produce 100% hemophiliac offspring.

b.  Matings that will produce 100% healthy offspring.

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SR.GENETICS.6B

BIOLOGY CURRICULUM 2006


ALTERNATIVE PATTERNS OF INHERITANCE PART III:

INCOMPLETE DOMINANCE:

SNAPDRAGONS

1.  Define INCOMPLETE DOMINANCE.

2.  Write two facts about snap dragons:

3.  A gardener crosses a white male snapdragon with a red female one.

a.  Complete a Punnett square of this cross.

b.  What are the genotypes of the offspring? ___

c.  What are the phenotypes of the offspring? ____

4.  The next year, the gardener crosses two of the offspring from the cross above (two pink flowers).

a.  Complete a Punnett square of this cross

b.  What is the phenotypic ratio among the offspring:

___ red: ___ pink:___ white

c.  What is the chance that two pink parents will have a red offspring? Express your answer in % _____

d.  What is the expected percentage of pink offspring from this cross? ___

5.  Examine the following Punnett squares.

1 / T / t / 2 / B / b
T / Tall / Tall / B / Black / Gray
t / Tall / Short / b / Gray / White

a.  Which one shows a cross involving incomplete dominance?

  1. Explain how you were able to identify the trait that is controlled by completely dominant alleles compared to the one involving incompletely dominant alleles.

ALTERNATIVE PATTERNS OF INHERITANCE PART IV:

APPLICATION

1.  Imagine that you are the Managing Horticulturist for a large nursery. You ordered one truckload of red flowering plants and one of pink because these colors are the best money-makers. However, your supplier did not have any pink flowers left and instead sent a truckload of all white flowers. Explain how you can possibly save your higher profits on pink flowers using what you know about incomplete dominance.

2.  Colorblindness is a recessive sex-linked trait. Your cousin Larry is colorblind and worried about the baby girl his wife, Trish, is carrying. Trish doesn’t know whether colorblindness runs in her family or not. Write a quick note to Larry and Trish explaining why females are less likely to inherit a sex-linked genetic disorder than males.

3.  Imagine that you have children with a person who has type AB blood. If you don’t know your own blood type, pretend that it is type A.

a.  What is the probability that you will have children with type B blood? Use a Punnett square to prove your answer.

b.  Use the Blood Transfusions table below to calculate the percentage of your children to whom you could donate blood.

BLOOD TRANFUSIONS
Blood Type / Can Receive
A / B / AB / O
A /  / 
B /  / 
AB /  /  /  / 
O / 

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