Genetics Unit II: Mendelian Genetics
(see guidelines on page 10)
Page 90
Genetics Unit II: Mendelian Genetics
At the end of this unit, I will:




Explore fundamentals of inheritance by examining cellular processes.
Know how to create and interpret a punnett square.
Know how to create and interpret a pedigree chart.
Be familiar with a specific genetic condition for which I will have created an
informational brochure.
Roots, Prefixes and Suffixes I will be able to understand when I see them in words are:


Homo-, hetero-, geno-, pheno-, co-, poly-zygous, -genic
The terms I can clearly define are:



Group One: Genetics, allele, dominant, recessive, homozygous, heterozygous,
genotype, phenotype, law of segregation, hybrid, and law of independent
assortment
Group Two: Carrier, pedigree
Group Three: Incomplete dominance, codominance, multiple alleles, epistasis, sex
chromosome, autosome, sex-linked trait, polygenic trait
The assignments I will have completed by the end of this unit are:












Mendelian Genetics Unit Cover Page
A brochure informing potential parents about a specific genetic disorder
Have learned about other genetic disorders from my classmates
Completed the Monohybrid Cross Worksheet
Understood common Human Genetic Traits through an independently-guided
activity
Completed the “Making Faces” Activity with a classmate and drawn our offspring
Completed the “Inheritance of Blood Types” worksheet
Partnered up with a classmate to finish the activity “How are Traits on Sex
Chromosomes Inherited?”
Completed the Genetics Review
Made a pedigree for the Gonzales family of Venezuela, tracking Huntington’s
Disease
Completed the pedigree questions for Duchenne Muscular Dystrophy
Mendelian Genetics Unit Concept Map
Page 91
Genetics Facts and Fallacies
The following 20 statements relate to various genetic principles, many of which are associated
with common false ideas and superstitions. Certain of the statements are true and others are
false. Read the following statements and record whether the statements are true or false.
______1. Certain acquired characteristics, such as mechanical or mathematical skill, may be
inherited.
______2. Identical twins are always of the same sex.
______3. Fraternal twins are more closely related to each other than to other children in a
family.
______4. The father determines the sex of the child.
______5. Each parent contributes half of a child's genetic make-up.
______6. Certain thoughts or experiences of a mother may mark or alter the hereditary makeup of an unborn child (not including drugs).
______7. Color-blindness is more common in males than females.
______8. A person may transmit characteristics to offspring that is not present in that person.
______9. Certain hereditary characteristics are influenced by the blood.
______10. Identical twins are more closely related than fraternal twins.
______11. Certain inherited traits may be altered by the stars, moon, or planets early in
development.
______12. Males are biologically stronger than females.
______13. The tendency to produce twins may run in families.
______14. A craving for a certain food, such as strawberries, may cause a birthmark on an
unborn child.
______15. Many of a person's inherited traits do not appear.
______16. The parent with the stronger will contributes more to a child's inheritance than the
other parent.
______17. If a person loses a limb in an accident, it is likely that he or she will have a child with a
missing limb.
______18. The attitude of parents toward each other influences the emotional make-up of an
unborn child.
______19. Children born to older parents lack the vitality (energy) of those born to younger
parents.
______20. The total number of male births exceeds female births each year.
Page 92
Genetic Disorders:
Expert group assignments
You have been assigned one of the following genetic disorders:
Color Blindness
Cystic Fibrosis
Down’s Syndrome
Duchenne Muscular Dystrophy
Edward’s Syndrome
Fragile X Syndrome
Hemophilia
Huntington’s Disease
Klinefelter’s syndrome
Marfan’s Syndrome
Patau’s Syndrome
Phenylkaptonuria
Sickle Cell Anemia
Tay-Sachs Disease
Turner’s Syndrome
Werner’s Syndrome
You will work alone on this project. If you have a disease that a classmate has, you may
collaborate during research, but you may not present the same material in your brochure. You
will design a brochure informing potential parents of your assigned genetic disorder.
In your brochure, you must answer the following questions:
1. How does this human genetic disorder occur? If inheritance is involved, is the trait
dominant or recessive?
2. How common is this disorder?
3. What group(s) of people are primarily affected by the disease?
4. What are the symptoms? How does the disease effect the afflicted?
5. Any other relevant information (see guidelines on page ____)
In addition to answering those essential questions, you must include the following technical
and design elements:
1. It must include a pedigree or a karyotype. The pedigree chart must have a minimum of
three generations. The first generation must have one parent that is a carrier or
displays the disorder. The karyotype must identify which chromosome is involved.
2. It must be interesting, creative, and tasteful. Include pictures of people with the
disorder. Be respectful of your subject and the audience.
3. It must be easy to follow and understand – create a smooth sequence, and include titles
for the different sections.
4. It must have at least three resources cited at the end of the brochure.
5. It must have a horizontal or landscape orientation.
6. It must have information on every fold of the brochure – each page should have at least
half of the information in text.
7. The font should be easy to read, not too large or too small. If in doubt, use the
standard, “Times New Roman,” size “12.”
Page 93
How to Make a Brochure Using Microsoft Word
Microsoft word already has a template prepared for you to make a brochure. All you have to do is cut
and paste your own text into the brochure and print it!
(1) To access this template, go to FILE and select NEW on the top of the screen, as shown:
Page 94
(2) A menu like this will pop up:
Double click on BROCHURE, or click on BROCHURE once and click OK.
(3) The template will be on your screen. It is already filled with words (garbage mostly). All you have to
do its cut those words out and paste or type in your own
(4) You have to be aware on how WORD orients the brochure on the screen versus what you actually
see when you print it out. Remember, brochures are double sided. Therefore, the template has a total of
2 pages (you have to scroll down for the 2nd page):
Page 95
Page 96
When you print you would have to print the first page first, then slide that same paper back into your
printer to print the 2nd page to get the double sided effect. You should play around with this with what
you have on the template so that you know how to print out your final copy. You should do this to know
how to orient the paper correctly - play around to familiarize yourself with it!
(5) You may print the brochure up in black and white, but if you would like to print your brochure up in
color – and you do not have access to a color printer. You may print it up on your teacher’s printer
BEFORE the due date. You may not print your brochure up on your teacher’s computer on or after the
due date.
You may want to follow the following suggested layout for your brochure:
The First Page of Your Brochure: This is the part that’s on the outside of the brochure when it is
folded. The following sections are in order, from the left to the right:
The first trifold: This will sum up the “meat” of your information. A suggested section for this is
“Prognosis.” This is where you will discuss information like how long a patient with this
disorder is expected to live, etc.
The second trifold: This should include your “Works Cited.” Be sure to cite every image that you
used. If you included any information that is not general knowledge (i.e., medical information
or statistics) cite where you got this information. Include the full web address, if accessed
online, not just “dictionary.com.”
The third trifold: This is the Cover of the brochure. Include the name of your disorder, your
name and your period. It is helpful to include an image and a brief summary of your disorder.
The Second Page of Your Brochure: This is the part that is folded in, and will contain the “meat” of
your information. The following folds are described, left to right.
The first trifold: You may want to make this fold “About (your disorder).” This is where you can
include the discovery of the disorder, how common the disorder is, and the group(s) of people
affected.
The second trifold: This should include your “Diagnosis” section. Include the tests that are
performed to determine if an individual has this disorder, the symptoms, and any risk factors
that make a person more likely to inherit this condition.
The third trifold: This is the “Heredity” section. You should include the karyotype or pedigree in
this section, as well as information about how this is inherited. If it’s known which
chromosome the disorder is located on, include this. If it is sex-linked or autosomal, you must
include this information. If it is dominant or recessive, this must be included.
Page 97
Genetic
Disorder
Klinefelter
Syndrome
How is it inherited?
What are the symptoms/
What’s the prognosis?
Down
Syndrome
Edward
Syndrome
Fragile X
Syndrome
Duchenne
Muscular
Dystrophy
Huntington’s
Disease
Patau
Syndrome
Werner
Syndrome
Turner
Syndrome
Hemophilia
Sickle Cell
Anemia
Color Blindness
Phenylketonuria
(PKU)
Marfan
Syndrome
Tay Sachs
Disease
Cystic Fibrosis
Page 98
After watching the video clip, briefly summarize Mendel’s observations:
____________________________________________________________________________________
____________________________________________________________________________________
Why did this happen? __________________________________________________________________
____________________________________________________________________________________
Page 99
Mendelian Genetics: A Brief History
What was an early idea about
Heredity?
The __________________ Theory:
• Main theory of inheritance until the late 19th
century.
• Each parent contributed factors that were
_______________ in the offspring.
What were the problems with
this theory?
1. _________________________________________
_________________________________________
2. _________________________________________
_________________________________________
Who was Gregor Mendel?
•
•
•
Augustinian monk who studied _________
plants
Established the _____________________
theory of heredity
Significance of work:
1. Developed ___________ _____________
•
Why did Mendel Research pea
plants?
2. Counted results and kept _______________
notes
His work remained undiscovered until _______.
1. They are normally ___________ pollinated, but can
be _____________________________.
2. They have several _________________ traits that
are easy to distinguish. (i.e., __________________)
What were the steps of
Mendel’s research?
1. Removed stamens from ____________ flower.
2. Transferred pollen from stamens of _________
flower to pistil of ___________ flower.
3. The pollinated flower matured into a pod.
4. Planted seeds from pod.
5. Examined offspring: ____________________
Page 100
Page 101
Mendelian Genetics: Mendel’s Conclusions
What was Mendel’s first
Conclusion?
1. Law of _________________________
a. Factors (genes) for a particular trait occur
in ____________.
b. For each trait, an organism inherits two
genes, one from each ________________.
c. Dominant alleles ____________ recessive
ones.
i. Exception 1: __________________
______________________
ii. Exception 2: __________________
d. Two alleles for each trait ______________
during gamete production.
What was Mendel’s second
Conclusion?
2. Law of __________________ ________________
If the genes are not connected, then they should
segregate ____________________.
Page 102
Monohybrid Cross Worksheet
Part A: Vocabulary
Match the definitions on the left with the terms on the right.
____ 1. genotypes made of the same alleles
A. alleles
____ 2. different forms of genes for a single trait
B. dominant
____ 3. gene that is always expressed
C. heterozygous
____ 4. gene that is expressed only in the homozygous state
D. homozygous
____ 5. genotypes made of two different alleles
E. recessive
Below each of the following words are choices. Circle the choices that are examples of each of
those words.
6. Dominant allele
D
e
k
L
N
n
R
S
d
F
G
r
k
P
mm
uu
Rr
TT
Oo
qq
Uu
ww
7. Recessive allele
M
n
8. Homozygous dominant
AA
Gg
KK
9. Homozygous recessive
ee
Ff
HH
10. Genotypes in which dominant gene must show
AA
Dd
EE
ff
Jj
RR
Ss
11. Genotypes in which recessive gene must show
aa
Gg
Ff
KK
rr
Oo
Tt
Part B: Punnett Squares
12. Examine the following Punnett squares and circle those that are correct.
D
d
D
D
A
a
A
a
d
Dd
dd
d
Dd
DD
A
AA
aa
a
Aa
aa
d
Dd
dd
d
Dd
Dd
a
Aa
Aa
a
Aa
aa
13. What do the letters on the outside of the Punnett square stand for? ______________________
___________________________________________________________________________
14. What do the letters on the inside of the Punnett square stand for? ________________________
___________________________________________________________________________
Page 103
15. In corn plants, normal height, N, is dominant to short height, n. Complete these four Punnett
squares showing different crosses. Then, shade red all the homozygous dominant offspring.
Shade green all the heterozygous offspring. Leave all the homozygous recessive offspring
unshaded.
N
N
N
n
N
n
N
n
N
N
n
n
N
n
n
n
16. In guinea pigs, short hair, S, is dominant to long hair, s. Complete the following Punnett squares
according to the directions given. Then, fill in the blanks beside each Punnett square with the
correct numbers.
a.
One guinea pig is Ss and one is ss.
Expected number of offspring:
____ Short hair (SS or Ss)
____ Long hair (ss)
b.
Both guinea pigs are heterozygous for short hair.
Expected number of offspring:
____ Short hair
____ Long hair
Part C: Monohybrid Cross Problems - Show your work.
17. Hornless (H) in cattle is dominant over horned (h). A homozygous hornless bull is mated with
a homozygous horned cow. What will be the genotype and phenotype of the first generation?
P1
F1
18. In tomatoes, red fruit (R) is dominant over yellow fruit (r). A plant that is homozygous for
red fruit is crossed with a plant that has yellow fruit. What would be the genotypes and
phenotypes of the P1 and F1 generations?
P1
F1
Page 104
19. If two of the F1 generation from the above cross were mated, what would be the genotypes
and phenotypes of the F2?
F1
F2
20. In humans, being a tongue roller (R) is dominant over non-roller (r). A man who is a non-roller
marries a woman who is heterozygous for tongue rolling.
Father’s phenotype ________
Mother’s phenotype _________
Father’s genotype ________
Mother’s genotype _________
What is the probability of this couple having a child who is a tongue roller? ________
21. Brown eyes in humans are dominant to blue eyes. A brown-eyed man, whose mother was
blue-eyed, marries a brown-eyed woman whose father had blue eyes.
What is the probability that this couple will have a blue-eyed child? _______
Page 105
Human Genetics- Mendelian Inheritance
INTRODUCTION:
Each human is unique. Except for identical twins this difference is due largely to differences in
genotype. Each human has approximately 30,000 genes which control his/her characteristics.
The autosomal traits mentioned in this lab are found on one of the first 22 chromosome pairs in
the nuclei of each of your cells.
PURPOSE:
To investigate the inheritance of human characteristics.
PROCEDURE:
Autosomal Traits.
Use the following information to determine which of the following traits you exhibit. Write your
phenotype in the appropriate space and circle your possible genotype(s).
1. The ability to taste the chemical PTC (phenylthiocarbamide) is an inherited
characteristic determined by a dominant gene. This harmless chemical can be
tasted by some people but not by others. Taste a piece of paper that has been
impregnated with PTC. If you detect a bitter taste, you are designated as a taster. If
you detect no taste other than the paper itself, you are known as a nontaster.
Your phenotype ________________________________
Your genotype(s)
TT
Tt
tt
2. A dominant gene determines that earlobes hang free and are not attached directly
to the side of the head. In some people, the earlobe is attached directly to the side
of the head, so that there is no lobe hanging free. The attached earlobe is due to a
recessive allele.
Your phenotype ________________________________
Your genotype(s)
Attached
FF
Ff
ff
Free
3. Some people can bend the distal, or end, joint of the thumb back beyond an angle
of 45o. This is called hitch hikers thumb. Normal thumb angle is dominant and
hitchhiker’s thumb is recessive.
Your phenotype ________________________________
Your genotype(s)
Normal thumb
NN
Nn
nn
Hitchhiker’s thumb
Page 106
4. Some people have the ability to roll the tongue into a U-shape when the tongue is
extended from the mouth and are known as a roller. This tongue rolling ability is
caused by a dominant allele. People who do not possess this allele can only produce
a slight downward curve of the tongue when it is extended from the mouth and are
known as a non-roller.
Your phenotype ________________________________
Your genotype(s)
Non-roller
RR
Rr
rr
Roller
5. Some people exhibit the characteristic of a hairline that comes to a distinct point in
the middle of the forehead. This is known as a widow's peak which results from the
action of a dominant allele. The recessive allele determines the characteristic of a
smooth hairline.
Your phenotype ________________________________
Your genotype(s)
Smooth Hairline
WW
Ww
ww
Widow’s Peak
6. Note the length of your big toe in relation to the length of your second toe. The
presence of a dominant allele determines that the big toe is shorter than the second
toe. A recessive allele determines that the big toe is longer than or equal in length to
the second toe.
Your phenotype ________________________________
Your genotype(s)
SS
Ss
ss
7. A dominant allele determines the presence of dimples. A recessive
gene determines the non-dimpled trait.
Your phenotype ________________________________
Your genotype(s)
Nondimpled
DD
Dd
dd
Dimpled
Page 107
8. A dominant allele determines the presence of freckles. A recessive allele determines
the nonfreckled trait.
Your phenotype ________________________________
Your genotype(s)
Nonfreckled
FF
Ff
ff
Freckled
9. Some people have the end of the little finger bent inward. This bent little finger is due
to the presence of a dominant allele. A straight little finger is due to a recessive allele.
To determine if you have the dominant or recessive allele, hold your hands out and
look at the angle of the little finger in relation to your palm.
Your phenotype ________________________________
Your genotype(s)
BB
Bb
bb
10. Note the presence of absence of hair on the middle joints of your fingers. The
presence of mid-digital hair is due to a dominant allele and the absence of middigital hair is due to a recessive allele. Other alleles determine whether hair will grow
on other joints of the fingers and the amount of growth. To observe the hair, hold
your fingers up to the light; some individuals have very light hair on their fingers.
Your phenotype ________________________________
Your genotype(s)
Absence of Hair
MM
Mm
mm
Mid-Digital Hair
DISCUSSION:
1. In this lab, how many dominant traits did you show?_____________________________
How many recessive traits did you show?________________________________________
2. If you have more dominant traits than recessive, does this mean you are a stronger
person than someone with more recessive traits?________________________________
Why or why not? _________________________________________________________________
_________________________________________________________________________________
3. A man who was heterozygous for normal thumb angle married a woman who had
hitchhiker’s thumb. Give the genotype of each parent and the chance of them
having a child with hitchhiker’s thumb.
Father's genotype_____________
Mother's genotype___________
Chance of having a child
with hitchhiker’s thumb ____________________
Page 108
Making Faces
You are heterozygous for each trait on your chromosomes. You will
combine your alleles with a classmate’s to see if your offspring look like
you – and hopefully not like this guy!
Partner up with a member of the opposite sex. If you are left with a
member of the same gender, one of you will have to use a class set of
chromosomes for the under-represented gender. If you are a boy, you
will have to use one of the class sets of chromosomes reserved for girls
(the pink one).
Once you have found your “mate,” move away from other pairs of two students and begin
by producing your gametes (this is called gametogenesis). Follow the instructions below to
make a baby!
1. Hold no more than three chromosomes at a time high in the air above your head.
2. Drop your chromosomes at the same time. If they do not twirl, drop them again.
3. When you pick up each chromosome, make sure that it stays in the position in which it
landed.
4. Repeat steps 1 – 3 for all of your chromosomes.
Once you have finished dropping chromosomes, it is time to figure out what combinations
you and your class-mate have!
5. Find a desk or lab bench and lay all of your chromosomes out in descending size order
(Chromosome 1 will be the largest and Chromosome 22 will be the smallest)
6. Use the “Genotype to Phenotype Translation Booklet” to determine what your baby will
look like. Start on the first page with “Sex Determination” and work through each trait in
the book.
7. Fill in the data log on the page as you combine traits with your class-mate. Make sure
to note the genotype and phenotype.
8. Once your chromosomes are organized, you should be able to answer the following:
What is the gender of your baby?
Use the table on the next page to fill in your genetic information. Remember that some traits
will have many genes that code for the trait!
9. Answer the questions that follow the data table, and on the following question sheet,
and in color, each partner should draw an accurate picture of their "child" based upon
the data collected above. The child’s name, as well as both parent’s names should be
written at the bottom of the image.
Page 109
Trait
Trait
No.
1
Face Shape
2
Chin Shape
3
Chin Shape
4
Cleft Chin
5
Skin Color
6
Hair Type
7
Widow's Peak
8
Color of Eyebrows
9
Eyebrow Thickness
10
Eyebrow Placement
11
Eye Color
12
Eyes-Distance Apart
13
Eyes-Size
14
Eyes-Shape
15
Eyes-Slantedness
16
Eyelashes
17
Mouth Size
18
Lips
19
Protruding Lip
20
Dimples
21
Nose-Size
22
Nose Shape
23
Nostril Shape
24
Earlobe Attachment
25
Darwin's Ear points
26
Ear Pits
27
Hairy Ears
28
Freckles on Cheeks
29
Freckles on Forehead
Gene from
Mother
Gene from
Father
Genotype
Phenotype
Page 110
Classmating Questions
1. When you originally cut the chromosomes up in pairs (before folding), these
represented the chromosomes of your cells. Are your cells diploid or haploid?
__________ Why?
2. When you folded the pair of chromosome and dropped them so only half of your
chromosomes were facing up, what does this have to do with sex cell formation?
_____
Were these sex cells haploid or diploid? ______________
Why? ______________________________________________________
3. What is the number of the chromosomes you had before you dropped them to the floor?
(think of both sides as being two separate chromosomes)
______________________________________________
4. How many chromosomes did you donate to the sperm or egg? (when you dropped
them) ______________________________________________
5. When you and your mate pushed the homologous pairs of chromosomes together, what
process did this represent? _________________________
6. What was the number of chromosomes in your new baby (after you pushed the
chromosomes together?) _____________________________
7. What is the female gamete called? ________________
What is the male gamete called? _________________
What process created the gametes? _____________________
8. Explain why people that had the genotype "ll" for non-prominent chin had to skip the
rest of the chin characteristics. _________________________
___________________________________________________________
9. How is it that there are so many colors of skin? _____________________
___________________________________________________________
___________________________________________________________
10. What is the difference between a genotype and a phenotype?
Page 111
Inheritance of Blood Types
The four basic blood types are determined by the presence or absence of the A and B
antigens in the red blood cells. For clarity, consider blood types as being determined by a single pair
of genes. Use the following information to complete the table below.
Blood Types
A
B
O
AB
Blood Types of
Parents
A and O
Possible Genotypes
IAIA or IAi
IBIB or IBi
ii
IAIB
All possible
genotypes of
parents
All possible
genotypes of
children
All possible blood
types of children
Blood types not
possible for
children
IAIA or IAi
IAi
A
B
ii
ii
O
AB
B and O
A and B
AB and A
AB and B
AB and O
O and O
Page 112
How Are Traits on Sex Chromosomes Inherited?
Introduction:
Genes for blood clotting and color vision are located on the sex chromosomes, specifically the X
chromosome. Remember, females have two X chromosomes (XX) while males have one X and one Y
(XY).
Hemophilia is a disease in which the person's blood will not clot. The disease is inherited. If
you have the dominant gene "H", you will have normal blood. If you have only the recessive gene "h",
your blood will not clot normally.
Color blindness is a genetic condition in which a person does not see certain colors, such as
green and red. This person will see green as a gray color and red as a yellow color. If you have at least
one dominant gene "B", you can see all colors. If you have only recessive genes "b", you cannot see
green and red.
In this lab you will
a. toss coins to show children born in four families.
b. see how hemophilia and color blindness are inherited in several families.
c. solve genetic problems involving hemophilia and color blindness.
MATERIALS:
envelope with 3 labeled coins
plastic bag with four labeled coins
PROCEDURE:
Part A- Hemophilia
A female can be XHXH, XHXh, or XhXh for blood clotting.
A male can be XHY, or XhY.
Family 1. Offspring of parents who are normal, the mother is a carrier for hemophilia.
1. Find the following coins in your envelope.
XH
Y
Coin 1
Male
XH
Coin 2
Female
Xh
These coins represent the genes of the parents. The coin with the Y chromosome is the father and the
coin with an X on each side is the mother.
2. Place both coins in cupped hands. Shake the coins and then drop them on the your desktop.
3. Read the combination of letters that appears. This combination represents the genotype observed in
an offspring of these parents.
4. In Table 1 below, make a tallymark (/) beside the correct genotype in the row marked "Offspring
Observed".
5. Repeat shaking and reading the coins for a total of 20 times.
Page 113
6. Total all offspring observed in the "Total" column.
7. For each genotype, calculate the number of expected offspring out of 20 offspring.
Use the expected number of each from your Punnett square on page 1. Record this
number in the row labeled “Expected Offspring Number”. If you have observed
offspring of a genotype not shown in Table 1 you may have used the wrong coins to
collect your data.
Table 1: Offspring of XHY Father and XHXh Mother
Gene Combinations
XHXH
XHXh
Observed Offspring
XHY
XhY
= 20
Observed Totals
= 20
Expected Offspring
Number
Family 2: Offspring of a father who has hemophilia and a mother who is a carrier for hemophilia.
1. Find the following coins in your envelope.
Xh
Y
Coin 1
Male
XH
Coin 2
Female
Xh
These coins represent the genes of the parents. The coin with the Y chromosome is the father and the
coin with an X on each side is the mother.
2. Place both coins in cupped hands. Shake the coins and then drop them on
on the your desktop.
3. Read the combination of letters that appears. This combination represents the
genotype observed in an offspring of these parents.
4. In Table 2 below, make a tallymark (/) beside the correct genotype in the row
marked "Offspring Observed".
5. Repeat shaking and reading the coins for a total of 20 times.
6. Total all offspring observed in the "Total" column.
7. For each genotype, calculate the number of expected offspring out of 20 offspring.
Use the expected number of each from your Punnett square on page 1. Record this
number in the row labeled “Expected Offspring Number”. If you have observed
offspring of a genotype not shown in Table 1 you may have used the wrong coins to
collect your data.
Page 114
Table 2: Offspring of XhY Father and XHXh Mother
Gene Combinations
XHXH
XHXh
XhXh
Observed Offspring
XHY
XhY
= 20
Observed Totals
= 20
Expected Offspring
Number
PART B- Color Blindness
A female can be XBXB, XBXb, or XbXb for the color vision gene.
A male can be XBY or XbY for the color vision gene.
Family 3.
Offspring of a father who is color blind and a mother who is homozygous
dominant.
1. Find the following coins in your plastic bag.
Coin 1
Xb
Y
Male
XB
Coin 2
Female
XB
These coins represent the genes of the parents. The coin with the Y chromosome is the father and the
coin with an X on each side is the mother.
2. Place both coins in cupped hands. Shake the coins and then drop them on
on the your desktop.
3. Read the combination of letters that appears. This combination represents the
genotype observed in an offspring of these parents.
4. In Table 2 below, make a tallymark (/) beside the correct genotype in the row
marked "Offspring Observed".
5. Repeat shaking and reading the coins for a total of 20 times.
6. Total all offspring observed in the "Total" column.
7. For each genotype, calculate the number of expected offspring out of 20 offspring.
Use the expected number of each from your Punnett square on page 1. Record this
number in the row labeled “Expected Offspring Number”. If you have observed
offspring of a genotype not shown in Table 1 you may have used the wrong coins to
collect your data.
Page 115
Table 3: Offspring of XbY Father and XBXB Mother
Gene Combinations
XBXB
XBXb
XbXb
Observed Offspring
XBY
XbY
= 20
Observed Totals
= 20
Expected Offspring
Number
Family 4. Offspring of parents who are normal but the mother is heterozygous.
1. Find the following coins in your plastic bag.
XB
Y
Coin 1
Male
XB
Coin 2
Female
Xb
These coins represent the genes of the parents. The coin with the Y chromosome is the father and the
coin with an X on each side is the mother.
2. Place both coins in cupped hands. Shake the coins and then drop them on
on the your desktop.
3. Read the combination of letters that appears. This combination represents the
genotype observed in an offspring of these parents.
4. In Table 2 below, make a tallymark (/) beside the correct genotype in the row
marked "Offspring Observed".
5. Repeat shaking and reading the coins for a total of 20 times.
6. Total all offspring observed in the "Total" column.
7. For each genotype, calculate the number of expected offspring out of 20 offspring.
Use the expected number of each from your Punnett square on page 1. Record this
number in the row labeled “Expected Offspring Number”. If you have observed
offspring of a genotype not shown in Table 1 you may have used the wrong coins to
collect your data.
Table 4: Offspring of XBY Father and XBXb Mother
Gene Combinations
XBXB
XBXb
XbXb
Observed Offspring
Observed Totals
XBY
XbY
= 20
= 20
Expected Offspring
Number
Page 116
Part C- Problems
For each of the following problems complete a Punnett Square then record your answers in the spaces
provided.
1. A mother who is heterozygous for blood clotting and a father who is normal for blood clotting want
to know what their children could be like for blood clotting.
Children
Number of
Number of
Males
Females
Have
Normal Blood
Have
Hemophilia
_______
_________
_______
_________
2. A mother who is homozygous dominant for color vision and a father who is color blind want to know
what their children could be like for color vision.
Children
Number of
Number of
Males
Females
Have
Normal Color Vision
_______
_________
Have
Color Blindness
_______
_________
3. A mother who is heterozygous for color vision and a father who is color blind want to know what
their children could be like for color vision.
Children
Number of
Number of
Males
Females
Have
Normal Color Vision
_______
_________
Have
Color Blindness
_______
_________
Page 117
Discussion Questions:
1. What are the sex chromosomes of females? ___________
2. What are the sex chromosomes of males? ___________
3. On which chromosome, the X or the Y, is the gene for color vision located? __________
4. How many genes do females have for color vision? ___________
5. How many genes do males have for color vision? ___________
6. On which chromosome, the X or the Y, is the gene for blood clotting located? _______
7. How many genes do females have for blood clotting? ___________
8. How many genes do males have for blood clotting? ___________
9. Why is there a difference in the number of genes for color vision and blood clotting in
males and females? ______________________________________________________________
10. In Part C, Problem 2, why are there no color blind children even though one of the
parents is color blind? ____________________________________________________________
_________________________________________________________________________________
11. From whom does a son inherit the trait of hemophilia? _____________________________
12. From whom does a daughter inherit the trait of hemophilia? _______________________
Page 118
Genetics Review: Dihybrid Cross, Incomplete Dominance, Codominance, Multiple
Alleles, and Sex-linked Inheritance
1.
How are dominant alleles represented? ___________________________________
How are recessive alleles represented? ___________________________________
2.
What do parents produce that combine to make a zygote? ____________________
3.
In humans, normal pigmentation (coloring in skin, eyes, and hair) is dominant to
albinism (no color in skin, eyes, or hair). Widow’s peak hairline is dominant to
smooth hairline.
a. What are the two traits being studied? ________________ and ________________
b. How would the normal pigmentation allele be represented? _____
c. How would the albinism allele be represented? _____
d. How would the allele for widow’s peak be represented? _____
e. How would the allele for smooth hairline be represented? _____
4.
If a homozygous normal pigmented person with a smooth hairline married an
albino who was homozygous for widow’s peak, what would be the genotype and
phenotype of their offspring?
Parental phenotypes:
Parental genotypes:
Parental gametes:
Offspring genotype:
Offspring phenotype:
normal pigmented, smooth hairline X albino, widow’s peak
____________ X ___________
_______
_______
__________
___________________________________
5. If one of the above offspring married an albino with smooth hairline, what would
be the possible genotypes and phenotypes of their offspring?
Parental phenotypes:
Parental genotypes:
Parental gametes:
______________________________ X albino, smooth hairline
____________ X ___________
_____ _____ _____ _____
_____
Offspring Phenotypes
Page 119
6. In radishes, the shape may be long or round or oval. Oval is the blended form
between the long and round forms and is due to incomplete dominance.
a. How would the long allele be represented? ________
b. How would the round allele be represented? ________
c. To be long, the organism would have to be homozygous long. What would be
the genotype of the plant that would produce long radishes? __________
d. To be round, the organism would have to be homozygous round. What would
be the genotype of the plant that would produce round radishes? __________
e. To be oval, an organism would have to be heterozygous. What would be the
genotype of the plant that would produce oval radishes? _______
f.
Fill in the Punnett square to show the cross between two plants that produce
oval radishes.
g. What is the genotypic ratio of the offspring in the above Punnett square?
____________________________________________
h. What is the phenotypic ratio of the offspring in the above Punnett square?
____________________________________________
7. A couple come into your office for genetic counseling. They want to know what
their chances would be of having a child with sickle cell anemia. The husband has
no known cases for sickle cell anemia in his family and tests negative for the marker
for sickle cell. The wife has a cousin with sickle cell trait and she, herself, tests
positive for sickle cell trait.
a. What is the husband’s genotype? __________
b. What is the wife’s genotype? _________
c. Fill in the Punnett square to show the possible genotypes of their children.
d. What is the chance of this couple having a child with:
normal RBC? ________ sickle cell trait? _________ sickle cell anemia? _________
Page 120
8. A husband and wife want to know what blood type(s) their children could have.
They are tested; the man has blood type A and the woman has blood type AB.
a. What is/are the possible genotype(s) for the man? _____________________
b. What is/are the possible genotype(s) for the woman? _____________________
c. Draw Punnett squares to figure out the possible genotypes their children might
have.
d. What blood type(s) could their children have? ________________________________
9. The gene for color vision is sex-linked; that is, it is located on the X sex chromosome.
a. What are the sex chromosomes for a female? _________
b. What are the sex chromosomes for a male? _________
c. How many genes for color vision do females have? ________
d. How many genes for color vision do males have? ________
10. A woman who is a carrier for red-green color blindness marries a man who is
color blind.
a. What is her genotype? _____________
b. What is his genotype? ____________
c. Fill in the Punnett square to show the possible genotypes their children might
have.
d. What is the probability of this couple having a:
child with normal color vision? ________
child that is color blind? ________
color blind son? __________
color blind daughter? _________
daughter who is a carrier for color blindness? __________
Page 121
Topic:
Beyond Mendel Outine of Topics
I) ____________________________________
II) ____________________________________
III) ____________________________________
IV) ____________________________________
V) ____________________________________
VI) ____________________________________
VII)
____________________________________
VIII)
____________________________________
I. Mutations
Definition:
A _________________ in the genetic material (__ __ __
or __ __ __) of a cell
- ________________: If it occurs in __________ cells, it
_______ be _________________ _____ to next generation
- _______-________: If it occurs in ________________, it
______ be passed on to next generation
2 Types of Mutations in Genes
1. ___________________ mutation
Affects ____ ____________________
(One nucleotide is ____________________ by another)
Point Mutation
_________ types of point mutations
a) _____________ mutations: code for a different
________ __________ (ex. sickle-cell hemoglobin)
– left diagram
b) _____________ mutations: code for the
__________ amino acid
c) _____________ mutaions: code for a _______
_____________.
Frameshift Mutation
2. ___________________ mutation: An ____________ or
________________ that shifts the triplet code
_____________ frame
a) Example of Insertion:
TACGCATGGAATACC
New sequence?
Page 122
b) Example of a deletion:
THE FAT CAT ATE THE RAT
New sequence?
Mutations in Chromosomes
1. __________________: A _______________ of the
chromosome is _________________ (not just ____
nuclotide)
2. __________________: A segment of the chromosome
is ____________________
3. __________________: A segment within a
chromosome is __________________.
4. __________________: A segment from one
chromosome _________ to another __________________
chromosome
II. Linked Genes
If genes are “linked”,this means they are ____________
on the _______________ ___________________________.
The linked genes are most likely ____________
________________ and will _____undergo Mendel’s Law
of
, unless _________
over ____________________ the linked genes
III. Gene Mapping
Genes that are ______________ together on the same
chromosome are _______ likely to cross over,
therefore, _______________.
Genes that are ____________ apart on the same
chromosome are __________likely to cross over and
segregate
IV. Sex-Linkage or (X-linked)
Genes that are on ______________chromosomes will
_____________ _______________ independently
When a gene is found on the ___ chromosome, it is
considered ___-__________________.
How are X chromosomes different
from the Y chromosome?
Explain how a gene can exist on the
X chromosome without existing on
the Y chromosome.
Page 123
When genes are sex-linked, we include the X and Y
as part of their genotype. For example, the allele for
red eye in fruit flies is not “R” but is written as _____.
How would you write the allele for
white eye in fruit flies?
You work in a fruit fly lab and you
cross
a heterozygote red-eye
female with a red-eye male. Predict
the F1 offspring using a punnett
square. What is the phenotypic
ratio?
Phenotypic Ratio:
V. Polygenic Traits
VI. Non-disjunction Disorders
Definition: Traits controlled by ______ or _______
_____________
Examples: ____________ _____________, _______________
Definition: When members of homologous
chromosomes fail to ___________________during
______________ – or – when _______________
______________ fail to ____________________ during
__________________.
Examples:_______________ Syndrome, _______________
Syndrome, _______________ Syndrome
VII.
Prenatal
Diagnosis
Using 1. Amniocentisis
Karyotypes
In your own words, explain the 2
ways karyotypes can be created to
diagnose diseases in a fetus
2. Chorionic Villus Sampling (CVS)
Page 124
VIII. Pedigree
A pedigree is a _______________ of the ____________
_______________ of family over several
________________.
Create a Legend
If A =
a=
Determine if the pedigree chart shows an autosomal
or X-linked disease.
a. If most of the ___________ in the pedigree are
affected the disorder is
.
Interpreting a Pedigree Chart
b. If it is a 50/50 ratio between ____ and __________
the disorder is
.
Determine whether the disorder is dominant or
recessive.
a. If the disorder is _______________, ___ of the
______________ ______ have the ______________.
b. If the disorder is _______________, ______________
parent has to have the disorder because they
can be ______________________.
Page 125
WEXLER'S SEARCH FOR THE HUNTINGTON'S GENE
The year was 1979, and Congress has just issued you the funding to study Huntington's disease - a
disorder afflicting more than 50,000 Americans. Very little was known about the inheritance of
Huntington's, but Dr. Nancy Wexler (whose mother died of it) knew about the incredibly high rate of the
disease around a place called Lake Maracaibo, Venezuela. Here, you'll be a part of a team sent to Lake
Maracaibo to study a large family (of more than 5,000 members!), and report your findings.
The family spans five generations. It is your job (as it was hers) to pedigree the family and see what's
going on here.
Below is a fax that has arrived from Lake Maracaibo...
To: Dr. _________________, Foothill University, Ventura, California
From: Huntington's research team, Lake Maracaibo , Venezuela
Dear Scientists,
What follows are the results of our interviews with 38 members of the Gonzales family. See what you
can make of it.
Sincerely.
The team
Generation V:
Luis, son of Zelda and Ramon. AFFLICTED
Generation IV:
Ramon, son of Ricardo and Lydia. AFFLICTED
Zelda, married to Ramon. HEALTHY
Felipe, brother of Ramon. AFFLICTED
Juan, son of Miguel and Letty. AFFLICTED
Cira, daughter of Miguel and Letty. HEALTHY
Roberto, son of Miguel and Letty. HEALTHY
Nora, daughter of Jesus and Margarita, AFFLICTED
Alejandro, son of Pedro and Beatriz. AFFLICTED
Delia, daughter of Dano and Andrea. AFFLICTED
Tio, son of Dano and Andrea. AFFLICTED
Maria, daughter of David and Guadelupe. AFFLICTED
Nariza, daughter of David and Guadelupe. AFFLICTED
Generation III:
Lydia, daughter of Carlos and Imelda. AFFLICTED
Ricardo, married to Lydia. HEALTHY
Helga, daughter of Carlos and Imelda. HEALTHY
Page 126
Letty, daughter of Carlos and Imelda. AFFLICTED
Miguel, married to Letty. HEALTHY
Margarita, daughter of Carlos and Imelda. AFFLICTED
Jesus, married to Margarita. HEALTHY
Beatriz, daughter of Carlos and Imelda. AFFLICTED
Pedro, married to Beatriz. HEALTHY
Juanita, daughter Javier and Bonita. AFFLICTED
Benito, son of Javier and Bonita. HEALTHY
Dano, son of Chito and Chelita. AFFLICTED
Andrea, wife of Dano. HEALTHY
David, son of Chito and Chelita. AFFLICTED
Guadelupe, wife of David. HEALTHY
Horatio, son of Chito and Chelita. HEALTHY
Lucio, son of Chito and Chelita. HEALTHY
Generation II:
Imelda, daugher of Rigo and Esmerelda. AFFLICTED
Carlos, married to Imelda. HEALTHY
Javier, son of Rigo and Esmerelda. AFFLICTED
Bonita, married to Javier. HEALTHY
Chito, son of Rigo and Esmerelda. AFFLICTED
Chelita, married to Chito. HEALTHY
Generation I:
Rigo. AFFLICTED
Esmerelda. HEALTHY
Page 127
Page 128
Genetics Unit II: Mendelian Genetics
The California State Standards I have come to use and understand are:

How to predict the probable outcome of phenotypes in a genetic cross from the
genotypes of the parents and mode of inheritance (autosomal or X-linked,
dominant or recessive).

The genetic basis for Mendel's laws of segregation and independent assortment.

How to predict the probable mode of inheritance from a pedigree diagram
showing phenotypes.
Page 129