Download MA STATE Frameworks: (This is what the state of

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2009-2010 CP2 GENETICS UNIT PACKET
FOR COMPLEX INHERITANCE
MA STATE Frameworks: (This is what the state of MA says you need to be able to do on your MCAS test)
Broad Concept: Genes allow for the storage and transmission of genetic information. They are a set of instructions
encoded in the nucleotide sequence of each organism. Genes code for the specific sequences of amino acids that
comprise the proteins that are characteristic of that organism.
3.3 Explain how mutations in the DNA sequence of a gene may or may not result in phenotypic change in an
organism. Explain how mutations in gametes may result in phenotypic changes in offspring.
3.4 Distinguish among observed inheritance patterns caused by several types of genetic traits (dominant, recessive,
incomplete dominance, codominant, sex-linked, polygenic, and multiple alleles).
3.5 Describe how Mendel’s laws of segregation and independent assortment can be observed through patterns of
inheritance (such as dihybrid crosses).
3.6 Use a Punnett Square to determine the probabilities for genotype and phenotype combinations in monohybrid
crosses.
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GENETICS: INCOMPLETE AND CODOMINANCE (10.3)
Exploring Life concept 10.3: There are many variations of inheritance patterns
TOPICS:




Incomplete Dominance
Codominance
Blood Typing
Sickle Cell Anemia
OBJECTIVES:
_________ 9. Explain the difference between complete dominance, incomplete dominance and codominance, and
solve genetics problems of each type of inheritance.
_________ 10. Explain what sickle cell anemia is and how it is inherited. Also explain its link to malaria.
_________ 11. Use Punnett squares to predict possible blood types from a cross.
_________ 12. Differentiate between the 4 major blood types; determine blood types of artificial blood (lab).
KEY TERMS:
Antigen: identifying molecule found on the surface of cells
Antibody: protein in blood plasma that attaches to a particular antigen
Codominance: inheritance pattern in which a heterozygote expresses the distinct traits of both
alleles
Intermediate inheritance: (also known as Incomplete dominance) neither allele for a trait is
dominant
Polygenic inheritance: combined effect of two or more genes on a single character
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NOTES: Incomplete Dominance (Otherwise known as “Intermediate Inheritance”)
•
•
•
•
•
In incomplete dominance, neither allele is dominant over the other
In the heterozygous individual, the phenotypes are blended.
The letter “C” is used to label the petal color gene.
Two different capital letters are used as superscript to show that neither color is dominant.
Do not use lower-case letters when demonstrating incomplete dominance.
Example of Incomplete Dominance
• In flowers, petal color is sometimes inherited through incomplete dominance.
Genotype
CRCR (sometimes seen as RR)
CWCW (sometimes seen as WW)
CWCR (sometimes seen as WR)
Phenotype
Red
White
Pink
NOTES: Sickle Cell Disease (An example of Incomplete Dominance)
•
•
•
People with sickle cell disease have red blood cells that contain an abnormal type of hemoglobin.
Sometimes these red blood cells become sickle-shaped (crescent shaped) and have difficulty passing
through small blood vessels.
When sickle-shaped cells block small blood vessels, less blood can reach that part of the body and it will
eventually become damaged from lack of oxygen.
Example of incomplete dominance in humans
Shape of red blood cells
• CR CR - all round (normal)
• CS CS - all sickle shaped (sickle cell disease)
• CR CS – cells are sort-of sickle, sort-of round (called
“sickle cell trait”) (a carrier)
Sickle Cell Disease
• In people with sickle cell disease, all red blood cells are
shaped like sickles (all SS)
• Serious health problems: blood can’t carry enough
oxygen to cells/ tissues/ organs
– Severe pain, Stroke, Chronic renal (kidney)
failure, Anemia (deficiency of hemoglobin), Etc…
• Individuals that are heterozygous (CR CS) have only mild health problems.
• But…they and individuals that are CS CS
• are protected against malaria!
• Sickle cell is therefore more common in areas with tropical climates.
Why are people with sickle protected against malaria?
• People with one or two alleles of the sickle-cell disease (CS CS OR CR CS) are resistant to malaria
because the sickle red blood cells are not conducive to the parasites
• In areas where malaria is common there is a survival value in carrying the sickle-cell genes.
• The malaria parasite (plasmodium) has a complex life cycle and spends part of it in red blood cells.
• People with sickle trait and sickle cell disease are not able to carry as much oxygen in the blood as those
who do not have the trait or the disease.
• The malaria parasite can not live in this low-oxygen environment.
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WS G2A: What
is Incomplete Dominance?
1. FIGURE A: The crossing of pure red (CRCR) and pure white (CWCW) four-o’clock
flowers
2. Fill in the Punnett square next to figure A
3. The offspring of crossed pure red and pure white four-o’clock flowers are
a. Only red
c. Only pink
b. Only white
d. Both red and white
4. In four-o’clock flowers,
a. Neither red nor white is
dominant
b. Red is dominant over white
c. Pink is dominant over red
d. White is dominant over red
5. Pink is a blend of which two colors? ___________________ and ___________________
6. Blended four-o’clock flowers have
a. Only genes for the color red
b. Only genes for the color white
c. Genes for both red and white
d. Only pink genes
7. Just by looking at the chart in figure A, how can you tell that there is incomplete
dominance?
FIGURE B: The crossing of pure black (CBCB) and pure white (CWCW) Andalusian
chickens
8. Fill in the Punnett
square next to figure B
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9. The offspring of crossed pure black and pure white Andalusian chickens are
a. Only white
c. Only black
b. A blend of black and white
d. Black and white
10. In Andalusian chickens
a. Both black and white are
dominant
b. White is dominant over black
c. Neither black nor white is
dominant
d. Black is dominant over white
11. What color are the offspring of black and white chickens?
12. Gray is a blend of which two colors? ___________________ and __________________
13. Blended Andalusian fowl have
a. Only genes for the color white
b. Only gray genes
14. Blended Andalusian fowl are…Choose:
c. Genes for both black and white
d. Only genes for the color black
pure / hybrids
15. FIGURE C: The crossing of pure red (CRCR) and pure white (CWCW) Shorthorn cattle
16. Complete the Punnett square in Figure C
17. The offspring of crossed pure red and pure white shorthorn cattle are:
a. Red and white
c. Only red
b. Only white
d. A blend of red and white
18. In shorthorn cattle,
a. pink is dominant over white
b. there is incomplete dominance
of red and white colors
c. white is dominant over red
d. red is dominant over white
19. What are red and white blended cattle called?
20. Roans have
a. Only genes for the color white
b. Genes for both white and red
c. Only genes for the color red
d. Only pink genes
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21. Roans are…Choose:
pure / hybrids
22. Complete each statement using a term or terms from the list below. Write your
answers in the spaces provided
Blending, roan calf, recessive, white, dominant, red, eye, skin, pure, hybrid,
strong, pink four-o’clock flower, incomplete dominance
23. A “hidden trait” is called a _________________________ trait
24. Not all genes are completely recessive nor completely _________________________.
Some are equally _________________________.
25. An individual that has only dominant or recessive genes for a trait is ________________
for that trait.
26. An individual that has both dominant and recessive genes for a trait is _______________
for that trait.
27. A condition where the genes for a given trait are equally strong is called _____________.
28. A combination of genes in which a mixture of both traits shows up is called
_________________________.
29. Two examples of offspring of incomplete dominance are _________________________
and the _________________________.
30. In four-o’clock flowers and roan cattle, neither the color ________________ nor the color
_________________ is dominant.
31. Incomplete dominance produces offspring with ________________ genes for the given
trait.
32. Examples of incomplete dominance in humans are found in
_________________________ and _________________________ color.
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WS G2B: INCOMPLETE DOMINANCE MONOHYBRID
CROSS PRACTICE PROBLEMS
1. Flower color in snapdragons is a trait showing incomplete dominance. It is governed by two alleles, C R and
CW, for red and white pigment production, respectively. Identify the expected phenotypic results (%)of the
progeny (offspring) from crossing:
1. Two pink flowered plants
2. Two white flowered plants
3. A pink flowered plant and a white flowered plant
2. Radish roots are long, round, or oval. When long-rooted radishes are crossed to round ones, the offspring all
have oval roots.
Symbols:
RL = Long
RD = Round
1. What type of inheritance is this? ___________________________________________
2. If oval-rooted radishes are crossed together, what will be the phenotypes and genotypes of the
offspring, and in what proportion?
Genotypes
%
Phenotypes
%
3. In cattle, red is incompletely dominant to white. When the two colors are crossed, the resulting cow is a pinkcolor called “roan.”
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Symbols:
CR
= Red
CW = White
1. A rancher has some roan cattle in his herd. He likes the color so well that he would like all his cattle
to be that color. Is it possible to develop a pure roan herd? Complete the Punnett square below for
two roan cows, and then explain your answer.
4. Sickle-cell anemia is a human hereditary condition in which the red blood cells, normally round, become
abnormally shaped. The problem is in the structure of the hemoglobin molecule. The red blood cells are
smaller and transport less oxygen than normal. They also tend to jam up in capillaries, causing hemorrhage
and thus anemia.
Symbols:
CRCR = normal hemoglobin and red blood cells
CSCS = high proportion of sickled cells and severe anemia
CRCS = some sickled cells and mild anemia
1. When two RS people marry, what are the expected genotypes and phenotypes of their children?
Complete the Punnett square below, and fill in the phenotype and genotype charts.
Genotypes
%
Phenotypes
%
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NOTES: CODOMINANCE




In codominance, BOTH alleles are equally dominant
In the heterozygous individual, BOTH phenotypes are expressed.
An Example of Codominance
o In flowers, petal color is sometimes inherited through codominance.
o The letter “C” is used to label the petal color gene.
Two different capital letters are used as superscript to show that each color is equally dominant. Do not use
lower-case letters when demonstrating codominance.
Genotype
CRCR
CWCW
CRCW
Phenotype
Red
White
Red AND White
Name: __________________________________________________________ Date: ____________ Class:______
WS G2C: CODOMINANCE MONOHYBRID
CROSS PRACTICE PROBLEM #1
In “pink pufferbelly pigs” spot color is inherited through codominance. Some pink pufferbelly pigs have pink skin with
green spots (SG). Some pink pufferbelly pigs have pink skin with purple spots and SP)
1. List the three possible genotypes and phenotypes for pink pufferbelly pig spot color below:
2. Show the results (genotypes, phenotypes and their percentages) of a cross between two pink pufferbelly pigs
heterozygous for the spot color gene.
10/26
NOTES: BLOOD TYPES (An Example of Codominance in Humans)




Blood types are determined by the presence or absence of a molecule on the surface of the red blood cells.
This molecule is called an “antigen”
“I” is the letter designated for the gene for blood type.
There are three possible alleles for this gene: IA
IB
i
Dominance of Alleles
 IA and IB are co-dominant to each other
 Both A and B are dominant over i
The Blood Types
 There are four blood types: A, AB, B, and O
 A person with type A blood could have the following genotypes:
 A person with type B blood could have the following genotypes:
 A person with type AB blood could have the following genotype:
 A person with type O blood could have the following genotype:
IAIA
IBIB
IAIB
ii
OR
OR
IAi
IBi
Antigens and Their Antibodies (see next page for chart)
 Blood Type A produces surface antigens for molecule A and B antibodies
 Blood Type B produces surface antigens for molecule B and A antibodies
 Blood Type AB produces surface antigens for molecules A and B and NO antibodies
 Blood Type O produces NO surface antigens and A and B antibodies
Makeup of Blood Types In the World
 Blood Type O: 45%
 Blood Type A: 40%
 Blood Type B: 11%
 Blood Type AB: 4%
Rh Factor
 Named after the Rhesus monkey where it was first identified.
 It is another blood antigen
 If you are Rh+, you have the antigen
 If you are Rh- you do not have the antigen
 Rh- individuals will produce antibodies against Rh+ blood if introduced.
 If an Rh- mother becomes pregnant with an Rh+ baby, the mother will produce antibodies against the Rh
antigen.
 This is not a problem during the 1st pregnancy.
 However, her blood will attack her baby’s blood if she becomes pregnant with another Rh+ baby in the future.
 Rh- mothers are given a drug called “Rho-gam” to neutralize the Rh+ in the baby’s blood.
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Name: ____________________________________________________ Date: ____________ Class: ______
WS G2D: Learning Blood Type Crosses
1.
What are the possible blood types of the offspring of a cross between individuals that are type AB
and type O?
2.
What are the possible blood types of the offspring of a cross between individuals that are type A
and type O?
3.
What are the possible blood types of the offspring of a cross between individuals that are both
type A?
4.
A brother and sister who have the same parents have the following blood types: Judy is blood
type A, and Mark is blood type O. What are the possible blood types of their parents?
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WS G2E: Blood Type Mystery!
Geneticists are often called upon to solve mysteries using some of the tools you have become familiar with in this
chapter. Using genetic clues, give a possible solution for each problem below.
PROBLEM: Four newborn babies in the delivery room of the hospital at the same time were mixed up by the person
who typed the wristbands. The blood types of the four babies were known to be AB, O, A and B. Hoe did the doctors
eventually find out which baby belongs to which set of parents? Parents #1 had blood types O and AB; Parents #2
had blood types AB and B; Parents #3 both had blood type O; Parents #4 had blood types O and A.
Possible Solution: Use Punnett Squares to determine possible genotypes of offspring.
Parents #1
Parents #2
Parents #3
OR
OR
1) Children’s blood types:
a) Children of parents #1 could be these blood types: __________________________
b) Children of parents #2 could be these blood types: __________________________
c) Children of parents #3 could be these blood types: __________________________
d) Children of parents #4 could be these blood types: __________________________
2) Baby with type AB blood belongs to: ___________________________
3) Baby with type B blood belongs to: ____________________________
4) Baby with type A blood belongs to: ____________________________
5) Baby with type O blood belongs to: ____________________________
Parents #4
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Name: ________________________________________ Date: _____________Class: _______
WS G2F: Blood Typing Practice
Human blood type is determined by codominant alleles. There are three different alleles, known as IA, IB,
and i. The IA and IB alleles are codominant, and the i allele is recessive.
The possible human phenotypes for blood group are type A, type B, type AB, and type O. Type A and B
individuals can be either homozygous (IAIA or IBIB, respectively), or heterozygous (IAi or IBi,
respectively).
Complete Punnett squares below to show all of the crosses of a woman with type A blood and a man with
type B blood and use your Punnett squares to answer the following questions.
1. What is the % chance that each of these children will be born to this couple:
Type A blood
_____________________
Genotype IB i
Type B blood
_____________________
_____________________
Genotype IBIB _____________________
Type AB blood _____________________
Genotype ii
Type O blood
_____________________
Genotype IAIA _____________________
Genotype IAIB ____________________
Genotype IAi
_____________________
_____________________
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Name: ______________________________ Date: ____________Class: __________
WS G2G: Whoops! Whose Baby?
1. A nurse at a hospital removed the wrist tags of three babies in the maternity
ward. She needs to figure out which baby belongs to which parents, so she checks
their blood types. Using the chart below, match the baby to its correct parents.
Show the crosses to prove your choices.
Parents
Blood Types
Baby
Blood type
Mr. Hartzel
O
Mrs. Hartzel
A
Jennifer
O
Mr. Simon
AB
Rebecca
A
Mrs. Simon
AB
Holly
B
Mr. Peach
O
Mrs. Peach
O
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2. A child has type A blood. What are ALL the possible blood types of its parents.
Show each cross to prove that it is possible.
17/26
GENETICS: SEX-LINKED INHERITANCE (10.5)
Exploring Life concept 10.5: Sex-linked traits have unique inheritance patterns
TOPICS:

Sex-Linked Inheritance
OBJECTIVES:
_________ 13. Use a Punnett square to predict outcome of cross for sex-linked traits.
_________ 14. Explain why most X-linked disorders are more common in males
KEY TERMS:
sex-linked trait: a character whose gene is found on a sex chromosome
XX: indicates female genotype
XY: indicates male genotype
18/26
GENETICS: PEDIGREES (12.3)
Exploring Life concept 12.5: Mendel’s Principles Apply to Humans
TOPICS:

Pedigrees
OBJECTIVES:
_________ 15. Compare and contrast all patterns of inheritance.
_________ 16. Construct and interpret pedigrees and explain their purpose.
_________ 17. Contrast dominant and recessive genetic disorders and explain the meaning of “carrier.”
_________ 18. Explain how traits are influenced by the environment.
KEY TERMS:
Carrier: an individual who has one copy of the allele for a recessive disorder and does not
exhibit symptoms
Pedigree: a family tree that records and traces the occurrence of a trait in a family
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NOTES: PEDIGREES
•
•
•
A pedigree is a graphic
representation of an
individual’s family tree
as it pertains to inherited
traits.
It permits patterns of
inheritance to be easily
recognized.
Generations are
numbered with roman
numerals, from top to
bottom.
MARFAN’S SYNDROME
•
•
•
•
A genetic disorder of the connective tissue.
It is sometimes inherited as a dominant trait. It is
carried by a gene called FBN1, which encodes a
connective protein called fibrillin-1.
People with Marfan's are typically tall, with long
limbs and long thin fingers.
Complications: defects of the heart valves, aorta,
lungs, eyes, dural sac surrounding the spinal cord,
skeleton and the hard palate (roof of mouth),
inflammation of connective tissue.
ALBINISM
•
•
•
Albinism is hereditary; it is not an infectious
disease and cannot be transmitted through contact.
The principal gene which results in albinism
prevents the body from making the usual amounts
of the pigment melanin.
Most forms of albinism are the result of the
inheritance of two recessive alleles.
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WS G2H: NEARSIGHTEDNESS
A pedigree is a diagram showing the phenotype of a trait for a certain group of related organisms. Scientists use
pedigrees to help them figure out the genotypes of an organism. The pedigree below shows a trait carried through a
family.
The squares represent males, while the circles are used to represent females. In this pedigree, the recessive trait for
nearsightedness, or myopia, is shown. The shaded areas show a person who has both recessive genes for
nearsightedness.
Let N = dominant gene for normal vision and n = recessive gene for nearsightedness.
On the lines below each numbered person, write his or her genotype.
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WS G2I: ALKAPTONURIA 1
This pedigree traces the inheritance of alkaptonuria, a chemical disorder which colors the urine and body tissues a
dark color. Examine the pedigree chart and answer the following questions.
1. Which family members have alkaptonuria?
2. Which family members are carriers for alkaptonuria?
3. Is alkaptonuria a dominant or recessive disorder? Explain.
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WS G2J: ALKAPTONURIA 2
THIS IS DIFFERENT FROM PROBLEM GIVEN OUT IN 2009-2010 PACKET!
The pedigree below traces the inheritance of Alkaptonuria, a biochemical, recessively
inherited disorder. Affected individuals are unable to break down a substance called alkapton,
which colors the urine and stains body tissues a darker color than normal.
1. What are the genotypes of George and Arlene?
2. What is Sandra’s genotype?
3. What is Christopher’s genotype?
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Name: ____________________________________ Date: __________________ Class: ________________
WS G2K: PEDIGREE: Dimples, Freckles, and Tongue-Rolling
Pedigree I traces the dimples trait through three generations of a family. Blackened symbols represent people with
dimples. Circles represent females and squares represent males.
1. Using the following passage, match each individual in the pedigree above to the person who is being
described below. Write each name underneath each shape above.
Although Jane and Joe Smith have dimples, their daughter, Clarissa, does not. Joe’s dad has
dimples, but his mother, and his sister, Grace, do not. Jane’s dad, Mr. Renaldo, her brother, Jorge,
and her sister, Emily, do not have dimples, but her mother does.
2. Make a pedigree based on the following passage about freckles.
Andrew, Patty, and Dylan have freckles, but their other, Mrs. Colbert, does not. Mrs. Giordano, Mrs.
Colbert’s sister, has freckles, but her parents, Mr. and Mrs. Lutz, do not. Deirdre and Darlene
Giordano are freckled, but their sister, Dixie, like her father, is not freckled.
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3. Determine the genotypes in the pedigree below. The trait being studied is the tongue rolling ability. Those
who cannot roll their tongue are recessive (tt).
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WS G2L: PKU PROBLEM
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NOTES / REMINDERS:
Complete dominance when one allele is completely dominant over another. The dominant trait
masks the presence of the recessive allele
Incomplete dominance (Intermediate inheritance) is when neither allele for a trait is dominant.
Individuals who are heterozygous have a phenotype that is a blended form of both parents. For
example, Red flowers have genotype RR and White flowers have the genotype WW. Pink
Flowers have genotype RW. Pink is a blend of red and white.
Codominance is when two alleles are equally dominant and are both expressed in a
phenotype. For example, Blood types A and B are both equally dominant, thus a heterozygote
with blood type AB expresses both the A and B alleles of the gene. The phenotype is NOT
blended, but both traits are expressed separately.
Polygenic inheritance occurs when multiple genes affect a character. Height and skin color in
humans are examples of polygenic inheritance.
-Example: Suppose there are three “tall” alleles for each gene (A, B, and C), each of
which contributes one “unit” of tallness to the phenotype. These tall alleles exhibit
intermediate inheritance with three “short” alleles (X, Y, Z). A person with genotype
AABBCC would be very tall, a person with genotype AXBBCC would be slightly less tall,
and so on.