Biology
140 –
Human
Biology
Lab
Notebook –
Human
Inheritance
Laura Ambrose
Luther College © 2012
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Contents
Human Inheritance ................................................................................................................................... 115
Introduction .......................................................................................................................................... 115
Learning Goals................................................................................................................................... 115
Learning Objectives ........................................................................................................................... 115
Checklist of topics covered and in-lab activities to complete .......................................................... 115
Background ........................................................................................................................................... 116
Genetics is about terminology .......................................................................................................... 116
Punnett Squares ................................................................................................................................ 118
Readings ................................................................................................................................................ 119
Pre-lab Questions.................................................................................................................................. 119
Lab activities and worksheets ............................................................................................................... 120
Karyotypes and Genetic Disorders.................................................................................................... 120
Genetic Traits .................................................................................................................................... 126
PTC Sensitivity: Linking genes and traits ........................................................................................... 133
Tracking two traits – Two gene cross................................................................................................ 135
Blood Type – Multiple Allele Inheritance and Co-dominance .......................................................... 138
Sex-linked traits – Colour Blindness .................................................................................................. 140
Incomplete Dominance – snapdragons ............................................................................................ 143
Human Height – Multifactorial Inheritance ...................................................................................... 145
Lab assessments.................................................................................................................................... 145
In lab.................................................................................................................................................. 145
Homework......................................................................................................................................... 145
Study guide ....................................................................................................................................... 146
Resources .............................................................................................................................................. 146
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Human Inheritance
Introduction
The study of inheritance is the study of how traits are passed from one generation to the next. Recall
that meiosis separates pairs of chromosomes and randomly puts them into gametes. Sexual
reproduction fuses the nucleus from one parent with the nucleus from the other parent, bringing
chromosomes back together into pairs. The traits that we have are the expression of genes on the
chromosomes.
Learning Goals
 To introduce basic patterns of genetic inheritance
 To introduce the Punnett Square as a tool for predicting outcomes of genetic crosses
Learning Objectives
1. After an introduction to the terminology of genetics and a discussion on basic patterns of
inheritance, students will understand how single-gene traits are inherited.
2. After a demonstration and explanation of Punnett Squares, students will be able to predict
outcomes of genetic crosses.
3. After a discussion and demonstration, students will understand more complex patterns of
inheritance.
Checklist of topics covered and in-lab activities to complete
- Karyotype activities
- Inventory of traits
- PTC case study
- Two gene cross, blood types, sex-linked traits, multifactorial inheritance
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Background
Staring at the family picture on the wall, Marcy again noticed how small Lucy was compared to all of the
other people in her family. Lucy was at least 6 inches shorter than the shortest sibling. Marcy and her
brothers used to tease Lucy about not really being part of the family, but it was clear looking at the
family pictures that Lucy was very much part of the family. Lucy’s eyes were very light blue, just like her
mother and grandfather, and her skin was dotted with the same freckles as her father. The similarities
continued with the pointy hairline, rounded earlobes, long fingers, and those dimples that everyone
thought was so adorable when Lucy was born. That cuteness, combined with Lucy being the baby of the
family, was probably what led Marcy and her brothers to torment her about her height. The most
important trait that Lucy inherited from her parents was patience to deal with incessant teasing from
siblings! With all those similarities, why was Lucy so very much shorter than the rest of the people in the
family? What other factors interacted with her genes to cause her to stop growing before everyone
else?
Genetics is about terminology
There are a lot of terms in genetics that seem very unfamiliar. It is important to understand these terms
in order to be able to understand the patterns of inheritance. Recall that the DNA in the human body
cells is organized into 46 chromosomes, which is further organized into 23 homologous pairs. Contained
within the DNA are genes, which are specific instructions for making specific proteins. The proteins are
then involved in building structures or directing biochemical reactions.
A person who studies genetics looks at the genes that determine the traits that we can see or measure.
Inheritance is the study of how these genes and traits are passed from one generation to the next,
including predicting the outcomes of genetic crosses.
An allele is an alternative form of a gene. For example, humans have genes for pigment in eyes and
there are different forms of the gene that relate to the different colours of pigments that the gene can
produce, such as brown pigment, blue pigment, gold pigment, or green pigment.
Sex chromosomes contain genes that have instructions for building and operating the sex organs that
determine the sex (male or female) of a person.
Autosomes are the chromosomes that contain genes that do not control the sex of the individual.
Recall that genes come in pairs, because chromosomes come in pairs, and that the genes are
instructions for proteins that determine the trait a person has. Also recall that the alleles in the pair
may, or may not, be the same. If the alleles are the same, the pair is called homozygous. The prefix
homo- means the same; -zygous refers to the zygote, or diploid, state. If the alleles are different, the
pair is called heterozygous. The prefix hetero- means different. Alleles are called dominant or
recessive, based on how the genes are expressed when they are together. A dominant allele is
expressed even when the recessive allele is present. A recessive allele is only expressed if there are two
recessive alleles in the gene pair. Genes are usually represented by single letters with an uppercase
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letter used for the dominant allele and a lowercase letter for the recessive allele. There are three
possible combinations of dominant and recessive alleles:
dominant-dominant
dominant-recessive
recessive-recessive
Homozygous dominant
Heterozygous
Homozygous recessive
Genotype
AA
Aa
aa
Phenotype
Brown eyes
Brown eyes
Blue eyes
When geneticists are studying the genes a person has, they are looking at that person’s genotype. When
doctors are looking at the traits a person has, they are looking at that person’s phenotype. The
phenotype refers to the traits that we can see and measure, such as eye pigmentation, cholesterol
levels, or the presence of polyps in the colon. The genotype is the genes that determine those traits.
A single-gene cross is when we look at one trait at a time to determine the possible outcomes of a cross
between two individuals. For example, we might try to figure out the possible outcomes for the
offspring for a father that is colour blind and a mother that is not colour blind.
A hybrid is another way to describe the heterozygote. A carrier also describes the heterozygote. The
term carrier usually refers to the situation where a person carries the recessive allele for a disease but
does not know they carry the recessive allele because it is masked by the dominant allele. A dihybrid is
the situation where a person is heterozygous for two traits. A dihybrid cross is a cross between two
individuals that are both heterozygous for two traits (TtAa and TtAa).
A genotypic ratio is a summary of the genotype results of the Punnett Square. A phenotypic ratio is a
summary of the phenotype results of the Punnett Square.
A karyotype is a picture of the chromosomes from a cell. A karyotype is created when cells are sampled
from an area of the body that is undergoing division. Recall that cells that are actively dividing have
chromosomes that are condensed and visible under a light microscope. The cells are treated to release
the condensed chromosomes from the nucleus and the chromosomes are photographed. The
chromosomes are organized in homologous pairs from largest to smallest, with the sex chromosomes
set at the end. Doctors use the karyotype to determine if a person has a genetic abnormality related to
chromosome structure or number.
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In this example, you can see there are 46 chromosomes and it comes from a human female.
Geneticists are compiling a list of human disorders that are related to chromosomal abnormalities. Here
are a few examples.
Chromosomal Makeup
46 XX
46 XY
13 trisomy
18 trisomy
21 trisomy
XXY
XO
Clinical Conditions
Female (normal)
Male (normal)
D1 syndrome
E syndrome
Down’s syndrome
Klinefelter’s
syndrome
Turner’s syndrome
Punnett Squares
A Punnett Square is a tool used to predict the possible outcomes of a cross between two individuals. In
order to draw a Punnett Square, you need to know the following information:
-
The genotypes and phenotypes of the parents
Whether the trait is autosomal or based on the sex chromosomes
Whether the trait is dominant or recessive
With this information you can determine the gametes of the parents, draw the Punnett Square, and
write genotypic and phenotypic ratios to explain the outcome. The information you need to draw the
Punnett Square is usually written into a word problem. Read through the following example.
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Cystic fibrosis (CF) is a recessive trait. Not having CF (A) is dominant over having CF (a). A man who is a
carrier for CF mates with a woman that does not have CF and is not a carrier for CF. Draw the Punnett
Square for this cross. Indicate the phenotypes, genotypes, and gametes of the parents. Write out the
genotypic and phenotypic ratios.
Phenotypes
Genotypes
Gametes
Male
Does not have CF
Aa
A or a
Female
Does not have CF
AA
A only
Punnett Square
A
A
A
AA
AA
a
Aa
Aa
Genotypic Ratio: 2 AA: 2 Aa: 0 aa
Phenotypic Ratio: 4 No CF : 0 CF
It is clear from this cross that there is a 0% chance of having a child with Cystic Fibrosis.
Readings
In order to be able to complete your lab on time and get the most out of it, complete these readings and
view the videos or animations before your lab period.
o
o
o
o
Textbook Chapter 20
Gregor Mendel’s work with pea plants (animation): http://www.dnaftb.org/1/animation.html
Here are some practice genetics problems. They are an online activity.
http://biology.clc.uc.edu/courses/bio105/geneprob.htm
Here are some tips for solving genetics problems: http://www.ableweb.org/volumes/vol21/mini.1.schwab.pdf
Pre-lab Questions
1.
2.
3.
4.
What traits do you have that you can see in your parents?
What traits to you hope you will pass on to your offspring?
What traits do you hope you will NOT pass on to your offspring?
A dog breeder wanted puppies that were light brown and had long tails. Using the tools you are
learning about in this lab, how might the breeder figure out which parents to mate?
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Lab activities and worksheets
As humans, we are often fascinated with our heredity. Starting when we are very young we are told
“You look just like your mother” or “I see you have your father’s eyes”. As we get older we start to
wonder “Will I lose my hair like my grandfather” or “Will I get the same wrinkles as my mother”.
Sometimes behaviours are associated between generations, such as having a fiery temper or a love of
reading. The study of inheritance is concerned only with those traits that are genetic, or based in the
DNA that makes up our genes.
Karyotypes and Genetic Disorders
1. How many chromosomes are found in genetically normal human cells?
2. What sex chromosomes are found in a genetically normal human male?
3. What sex chromosomes are found in a genetically normal human female?
Look at the following karyotypes. Beside each karyotype indicate:
1) how many chromosomes are present
2) which sex chromosomes are present
3) whether or not the genetic state is normal.
If the genetic state is not normal, use the table in the background section to determine what disorder
the person has.
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Example 1
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Example 2
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Example 3
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Example 4
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Example 5
This activity is a TA Checkpoint. Have your karyotypes checked and initialled by a lab Teaching
Assistant.
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Genetic Traits
We are often curious about the traits we have, where they came from, and how they are going to be
passed down to our offspring. Many human traits are controlled by single genes in our genome. Answer
the following questions and then figure out how common the traits are in your group.
Adapted from “Alike But Not The Same” in Human Genetic Variation, NIH Curriculum Supplement Series
1999. http://science-education.nih.gov
An Inventory of My Traits - Survey
What combination of these traits do you have? Complete the survey to find out.
1. I have detached earlobes
 Yes  No
2. I can roll my tongue
 Yes  No
3. I have dimples
 Yes  No
4. I am right-handed
 Yes  No
5. I have freckles
 Yes  No
6. I have naturally curly hair
 Yes  No
7. I have a cleft chin
 Yes  No
8. I have allergies
 Yes  No
9. I cross my left thumb over my right when I clasp my hands together
 Yes  No
10. I can see the colors red and green (I am not color blind)
 Yes  No
11. The hairline on my forehead is straight.
 Yes  No
12. I am a:
 Male Female
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An Inventory of My Traits - Data Table
How many people in your group have each trait?
Fill in the data table below by
counting the number of people
who marked “yes” and the
number of people who marked
“no” for each trait. Trait
Detached earlobes
Yes
No
Tongue rolling
Dimples
Right-handed
Freckles
Naturally curly hair
Cleft chin
Allergies
Cross left thumb over right
See the colors red and green
Have a straight hairline
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An Inventory of My Traits - Data Table
Draw a bar graph to show how many people in the group have each trait. It might help to turn your
paper sideways and draw the X axis along the long edge of the paper.
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The Case Study – To the Bitter End: A Case Examining the Genetics of PTC Sensitivity
by R. Deborah Overath, Department of Life Sciences, Texas A&M University – Corpus Christi
"Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New
York, all rights reserved. Used with permission." This case study has been adapted for this lab.
The purpose of this case study is to demonstrate that, sometimes, scientific discoveries are made by
accident. Scientists have to be aware of what they are observing and be able to follow interesting
questions with inquiry. This early research into PTC tasting has led to decades of further research. Work
through the case study and then taste the PTC paper for yourself.
Part I – Discovery*
“Arthur,” said C.R. Noller in an irritated voice, “what the heck are you doing over there? Why did you let
that awful tasting stuff get into the air? It’s so bitter that I want to vomit!” Drs. Arthur Fox and C.R.
Noller were working separately in a lab at the DuPont Chemical Company’s facilities in Wilmington,
Delaware.
“What do you mean, C.R.?” snapped Arthur. “I don’t taste anything, and I’m right on top of this stuff.”
“It’s got to be that powder you’ve got there,” retorted C.R. “I’m not working with anything bitter, and
I’m too far from the door for it to be coming from outside the lab.”
Arthur was transferring some phenylthiocarbamide (PTC) into a bottle. During the transfer, some of the
white powder had dispersed into the air.
“Look,” said Arthur as he licked his finger, picked up a few PTC crystals, and licked his finger again. “I
don’t taste anything.”**
“Arthur,” said C.R., “give me some of that stuff. I really don’t want to taste it, but I’ll do it just to prove
you’re wrong!”
Arthur Fox brought the bottle of PTC over to C.R. Noller, who picked up a few crystals. As soon as the
crystals touched his tongue, C.R. exclaimed, “Yuck! Quick—get me something to rinse out my mouth!
That stuff is just too bitter!”
After C.R. rinsed out his mouth with some water, Arthur said, “Let’s see if we can find some other folks
to taste this PTC to see if they taste anything.”
For several days Arthur asked all his co-workers, friends, and acquaintances to taste his PTC powder and
found that neither he, nor C.R., were unique. Regardless of gender, age, or ethnicity, about 60% of
people tasted PTC as bitter, like C.R. The other 40% were, like Arthur himself, taste blind: PTC had no
taste to them. Arthur also tested closely related chemicals with the same results.
News of Arthur’s discovery was published in Science, the premier American science journal (Anonymous
1931). Shortly thereafter Arthur received the following letter:
Dear Dr. Fox,
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I read the news of your discovery of variation in the ability to taste phenylthiocarbamide (PTC) and related
compounds with great excitement. I am studying Mendelian markers in human populations. Unfortunately, we
have few examples of such traits in humans, as you can see from my article recently published in the Eugenical
News (1931b), which I have enclosed. Would you please send me some PTC? I would like to study this variation in
tasting ability to see if it is inherited and, therefore, can be used as a Mendelian marker.
Sincerely yours,
L.H. Snyder, Ph.D.
Professor of Genetics
Ohio State University
* The basic facts, scenarios, and players in this case are found in the literature. For example, Arthur Fox
did discover variation in PTC sensitivity in the way described, his discovery was a news item in Science,
and L.H. Snyder did write to Fox as indicated (see Anonymous 1931, Fox 1932, and Snyder 1931a).
However, this narrative is a fictionalized account of these events.
** It is important to note that good laboratory practice and safety dictate that chemicals should not be
tasted in the laboratory.
1. What is his hypothesis?
References
Anonymous. 1931. Science news: taste blindness. Science (Suppl.) 73: 14a.
Fox, A. L. 1932. The relationship between chemical constitution and taste. Proc. Natl. Acad. Sci. USA 18:
115–120.
Snyder, L. H. 1931a. Inherited taste deficiency. Science 74: 151–152.
Snyder, L. H. 1931b. Linkage in man. Eugenical News 16: 117–119.
Part II – Mendelian Genetics
After obtaining some PTC from Arthur Fox, L.H. Snyder determined the PTC phenotype (can taste or
cannot taste) for the members of 100 nuclear families. He first verified that gender was not a factor by
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comparing the number of male tasters and non-tasters to the number of female tasters and non-tasters.
Because there was essentially no difference between sexes, Snyder grouped families by the phenotypes
of the parents, disregarding the gender of each parent, and tabulated his data (Snyder, 1931a):
Phenotypes of Children
Can taste
Cannot taste
Parent phenotype combination
Number of families
Both parents can taste
40
90
16
One parent can taste,
the other cannot
51
80
37
Neither parent can taste
9
0
17
Questions – Answer the following questions based on what you know and what your group members
know. Make jot notes to use during the lab discussion
1. What kind of evidence would indicate that the ability to taste PTC is inherited?
2. Why was it important for Snyder to verify that males and females had similar proportions of
tasters and non-tasters?
3. Why do couples who can taste PTC have children who cannot?
4. What is the significance of the fact that couples who cannot taste PTC ever have children who
can?
Reference
Snyder, L. H. 1931a. Inherited taste deficiency. Science 74: 151–152.
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PTC Sensitivity: Linking genes and traits
Phenylthiocarbamide (PTC) is an anti-thyroid drug that prevents the thyroid gland from incorporating
iodine into the thyroid hormone. The ability to taste PTC is associated with the functioning of the thyroid
gland. Since the early 1930s, when the ability to taste PTC was discovered, researchers in diverse areas
of science, including genetics, ecology, evolution, nutrition and psychology, have all contributed to
understanding the role of the gene that controls for the ability to taste PTC in our evolutionary history.
In this activity you will get the opportunity to determine if you are a PTC taster or not. You will need to
get a piece of paper that has been impregnated with PTC. Also note the following information:
-
The gene for tasting PTC is on an autosome
Tasting (A) is dominant over not tasting (a)
Put the PTC paper on your tongue to determine if you are a taster. If you are a taster, you will know it
right away. If you are not a taster, take a look around because watching tasters taste PTC is quite
amusing! Dispose of the PTC paper where indicated by your lab TA.
1.



Were you able to taste the PTC in the paper?
Tasted like paper
Tasted bitter
Tasted TERRIBLE!
2. What do you think your genotype is? Explain.
Genetics Problem: Joe cannot taste PTC, but both his mother and father can taste PTC.
a. What is Joe’s genotype?
b. What genotype do Joe’s parents have?
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c. Draw the Punnett Square for the cross between Joe’s parents. Include the genotypic and
phenotypic ratios.
d. What is the percent chance that a child will be able to taste PTC?
e. What is the percent chance that a child will not be able to taste PTC?
This activity is a TA Checkpoint. Have your Punnett Square checked and initialled by a lab Teaching
Assistant.
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Tracking two traits – Two gene cross
Finger length is determined by a single gene and is long or short. Hairline is also determined by a single
gene and can be straight or pointed. A pointed hairline is often referred to as a Widow’s peak. Tracking
two traits together can answer the question as to whether or not some traits are always inherited
together. In order for the Punnett Square to answer the question, we have to be looking at traits that
are generally found on separate chromosomes.
Genetics Problem
Finger length: Short Fingers (A) is dominant over long fingers (a)
Hairline: Widow’s peak (B) is dominant over straight hairline (b)
Think about tracking these two traits together. Write in all of the combinations of gene pairs. Use the
first two as examples.
Genotype Description
Homozygous for short fingers
and Widow’s Peak
Homozygous for short fingers,
heterozygous for hairline
Genotype
AABB
Gametes
AB
AABb
AB, Ab
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A man and a woman that are both heterozygous for short fingers and Widow’s Peak have children. Draw
the Punnett Square for this cross. Write out the genotypic and phenotypic ratios. What is the name
given to this pattern? Hint: we discussed it in class.
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A man with long fingers and a straight hairline has children with a woman that is heterozygous for both
short fingers and Widow’s Peak. Draw the Punnett Square for this cross. Write out the genotypic and
phenotypic ratios.
This activity is a TA Checkpoint. Have your Punnett Square checked and initialled by a lab Teaching
Assistant.
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Blood Type – Multiple Allele Inheritance and Co-dominance
Red blood cells have proteins on the outside of the plasma membrane and these proteins indicate the
type of blood a person has. The cell knows what proteins to put on the outside of the plasma membrane
based on the genes for blood type. For many genes there are only two alleles, or two options for the
gene. In the case of the gene for blood type, there are three alleles, or three different possibilities for
blood type. There are two dominant alleles and 1 recessive allele.
Allele
Dominant/Recessive
A
Dominant
B
Dominant
o
Recessive
The fact that there are two dominant alleles makes for a unique outcome when the two dominant
alleles are paired in the cells.
Genotype
Phenotype/Blood
type
AA
A
Ao
A
BB
B
Bo
B
oo
O
AB
AB
Genetics Problem: Mark has blood type O. His mother has blood type A. Two men provide blood
samples to try to figure out which might be Mark’s father.
a) What is Mark’s genotype?
b) What is Mark’s mother’s genotype?
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c) Male A has blood type AB. Could he be Mark’s father? Explain.
d) Male B has blood type B. Could he be Mark’s father? Explain.
This activity is a TA Checkpoint. Have your Punnett Square checked and initialled by a lab Teaching
Assistant.
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Sex-linked traits – Colour Blindness
Sex chromosomes have genes that determine the sex of the individual. The X chromosome is larger than
the Y chromosome, and also has genes that determine traits other traits, such as colour vision. Colour
blindness is an X-linked, recessive trait, which means the genes are on the X chromosome. The
abbreviations for the chromosomes carried on the X chromosome are written in the capital letter for the
dominant allele and lowercase letter for the recessive allele, both written as superscripts to a capital
letter X.
XA – normal colour vision
Xa – colour blind
Fill in the following table, listing the possible genotypes and phenotypes for colour blindness. Remember
to indicate if the person is male or female.
Genotype
Phenotype
XA XA
Female, normal vision
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Have someone in your group present the colour blindness chart to you. Write down what you see in a
place that your partner cannot see it. Keep your answers hidden until all members of your group have
been tested. Colour blind people see different things than people with normal colour vision.
Fill in the following information:
Your phenotype
Your genotype
Your father’s phenotype and genotype
Your mother’s phenotype
Draw the Punnett Square for your family.
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Genetics Problem: Jane and her mother are not colour blind, but her maternal grandfather was colour
blind. What are her maternal grandfather’s and her mother’s?
What are Jane’s possible genotypes?
If Jane’s father is not colour blind, is there a possibility that Jane could have colour blind siblings? Draw
the required Punnett squares to answer this question.
This activity is a TA Checkpoint. Have your Punnett Square checked and initialled by a lab Teaching
Assistant.
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Incomplete Dominance – snapdragons
In some cases, the dominant allele is not completely dominant over the recessive allele. When this
happens, the recessive trait blends with dominant trait to create an intermediate phenotype in the
offspring.
Genotype
AA
Aa
aa
Phenotype
Dominant
Intermediate
Recessive
Genetics Problems: In snapdragons, flower colour (red, pink, white) results from a pair of alleles where
the dominant, red, allele is not completely dominant over the recessive, white allele. A plant with red
flowers is crossed with a plant with white flowers.
What are the genotypes of the parents?
What types of gametes does each parent make?
Draw the Punnett Square for this cross.
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What are the expected genotype and phenotype ratios for their offspring?
Draw the Punnett Square for the offspring of the first cross.
What are the expected genotype and phenotype ratios of this cross?
Blending inheritance is the idea that the traits of the parents are blended in the offspring. How is flower
colour in snapdragons an example that might support the hypothesis of blending inheritance?
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Human Height – Multifactorial Inheritance
Some human traits are controlled by more than just the genes that are inherited from the parents. Some
traits are also strongly influenced by environment factors. Human height is an example of a trait that is
controlled by both the genes a person has and the environment they are in during development. In
humans, a person has genes that dictate the ultimate height that person can grow to. The expression of
those genes is affected by early childhood nutrition. If a young child has good nutrition while they are a
toddler, they are more likely to grow to the maximum height dictated by their genes. If a young child has
poor nutrition while they are a toddler, they are less likely to reach the maximum height dictated by
their genes. The genes for height are inherited following the patterns of Mendelian genetics.
Thinking back to the story presented at the beginning of the lab, how might multifactorial inheritance
explain why Lucy is shorter than the rest of her family? What information is missing from the story that
would help you figure this out?
Lab assessments
In lab
- Karyotypes
- Punnett Squares
- Case study questions
Homework
- Study concepts using study guide
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Study guide
Outline of topics that should be understood for the lab exam
1. Understand the genetics terms from the lab. Create a glossary of the terms. Consider using cue
cards.
2. Understand how a karyotype is created and used. What kinds of questions can be answered
with a karyotype?
3. Understand how a Punnett Square is made and how it can be used to predict outcomes of
crosses.
4. Understand the history of the discovery of the ability to taste PTC.
5. Understand the 9:3:3:1 phenotypic ratio of a cross between heterozygotes when tracking two
traits at a time.
6. Understand the multiple alleles involved in blood typing. Work through the examples to
determine when blood typing can be used to determine the parents of a child.
7. Understand how sex-linked traits found on the X chromosome are inherited and expressed.
Understand the example of colour vision.
8. Understand how incomplete dominance works and the example of snapdragons.
9. Relate the information on multifactorial inheritance to the story about human height at the
beginning of the lab.
Resources
Mendelian Genetics: http://www.dnaftb.org/1/
Karyotype Activity:
http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html
PTC: http://www.ncbi.nlm.nih.gov/pubmed/11293722
More PTC: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1456409/
Human height and childhood nutrition: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2258311/
EXTRA QUESTIONS: http://biology.clc.uc.edu/courses/bio105/geneprob.htm
http://www.ksu.edu/biology/pob/genetics/intro.htm
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