Download Better Living Through Genetics

Name ________________________________________________ Score _______
Better
Living
Through
Genetics
Edible DNA
Materials



2 Twizzlers™
6 toothpicks
12 colored marshmallows (three of each color)
Safety Concerns: Possible student allergy to foods being
used, toothpicks. Ask students if they have an allergy to any
of the foods being used. Discuss proper use of toothpicks.
Procedures
1. Lay out your materials on your desk.
2. Using your Twizzlers™, lay out the sides of the DNA molecule.
3. Assemble your marshmallow rungs. Remember, A only goes with T and C only goes with G.
Make one color of marshmallow represent each base.
Adenine
Cytosine
Guanine
Thymine
4. Place one marshmallow on one end of your run and its partner on the other end. You should
have 12 runs on your ladder when you are done.
5. Place each rung onto your licorice sides. Try and space them out evenly. You may place them
in any order that you want. Make sure you do not have two of the same color marshmallows on
one toothpick.
6. Twist your DNA molecule so that it looks like a double helix.
7. Identify the marshmallow bonds on your DNA molecule below:
Chemical
Marshmallow Color
Adenine
Cytosine
Guanine
Thymine
8. Once you are done, you must have your DNA graded.
DNA model was completed correctly (Mr. Hill’s initials) _________
(used with Mr. Jones’ permission)
Color-Coded DNA
Introduction
Many people now get their DNA tested for hereditary diseases, including Huntington’s
Disease and some cancers. But soon, DNA may also be used to diagnose infectious
diseases, from salmonella to HIV. In this Science Update, you’ll hear about a developing
technology that could make this possible.
Article
Seeking out DNA. I'm Bob Hirshon and this is Science Update.
Most people associate DNA analysis with paternity tests and criminal investigations. But
it can also be important for diagnosing illness.
Bruce Armitage is a chemist at the Center for Light Microscope Imaging and
Biotechnology. He’s working on basic technology that could become a quick and easy way
to screen for bacterial and viral DNA in the blood.
He says it’s based on a molecule called PNA and a group of special dyes. PNA is a labcreated version of DNA. It can be made so that it will seek out and connect to a specific
DNA sequence.
Armitage:
By designing our PNA to have the right shape we can distinguish a viral DNA or a
bacterial DNA from a human DNA.
Armitage and his colleagues found that they can see if the PNA has found its target by
adding special dyes to the mix.
Armitage:
What we’ve found is that certain types of cyanine dyes will stick to a ladder where one
of the strands is DNA, and one of the strands is PNA. And when they stick, they change
color from blue to purple.
Armitage says right now the test is only used in the research lab, but it could be
improved for wider applications. For the American Association for the Advancement of
Science, I'm Bob Hirshon.
Making Sense of the Research
Bacterial and viral infections can be hard to spot. Often, a diagnosis is made based on
symptoms. In the case of viral infections, even a firm diagnosis is done indirectly, by
looking for antibodies that the body makes to fight the virus.
This technique may make it possible to diagnose infections more quickly, efficiently, and
confidently. The key player in the technology is PNA, an artificial version of DNA, the
molecule that contains a living thing’s genetic code. (PNA can also mimic RNA, a DNAlike molecule that viruses use instead.)
PNA can be made to look like any specific strand of DNA or RNA. If it comes near a
strand that matches, the PNA will stick to it. Since the genetic code of each organism is
unique, it’s possible to manufacture PNA strands that will stick to bacterial or viral
DNA, but not to human DNA.
Armitage says it’s easier to do this with PNA than with actual DNA for two reasons:
First, because you can synthesize as much PNA as you want, and make it exactly how you
want it. Second, because PNA is more stable than DNA, it binds more firmly to its
target and doesn’t tend to come apart.
Once the PNA binds to its target, the question is, how do you see it? That’s where the
dye, called cyanine, comes in. Cyanine dyes are the same light-absorbing dyes that are
used in color photography. When PNA binds to DNA, the attached dye molecules end up
stacking tightly on top of each other, and the apparent color changes from blue to
purple. You can see this happen with the naked eye; all you need to do is put a couple of
drops of cyanine dye in a small well where a DNA sample – from the blood, for example –
is mixed with PNA. If it changes color, the bacteria or virus is present; if not, it isn’t.
Armitage says it isn’t easy to make just the right strand of PNA. That’s because the
strands of DNA and RNA don’t lie flat in living tissue: they’re all tangled up like
spaghetti. Sometimes a strand of PNA can’t bind to its target, because the section of
DNA it matches up with isn’t exposed. So the researchers have to keep trying until they
find a strand of PNA that works.
Although the idea here is to diagnose infectious diseases, this isn’t the only potential
use for this technology. It could also be used to diagnose genetic diseases more easily.
If scientists could manufacture a strand of PNA that matched up to a genetic sequence
that causes a disease, they could turn it loose on a blood sample to see if the defective
gene is there – even if the patient doesn’t have any symptoms yet.
1. What is PNA? How is it different from DNA or RNA?
2. How can it be used to spot bacterial or viral DNA?
3. Why are the cyanine dyes essential to this technique?
4. What are the advantages of this technique, compared with looking for the antibodies
to a virus? Compared with diagnosing an illness based on the symptoms?
5. Some kinds of genetic testing – for example, for incurable diseases – have provoked
controversy. Why do you think that is? Think of possible arguments for and against this
kind of testing?
Arguments For
Arguments Against
Genes and Geography
Introduction
Our early human ancestors began migrating across the globe tens of thousands of years
ago. Some left behind archaeological evidence of their travels. But as you'll hear in this
Science Update, another record of where we come from and where we've been might be
found right in our DNA.
Article
Genes and geography. I'm Bob Hirshon and this is Science Update.
People around the world might look different from one another, but inside, we're pretty
similar—and that's true even of our genes. That's according to a recent study in the
journal Science.
Noah Rosenberg is a research associate at the University of Southern California. Using
a computer program, he and his colleagues analyzed the genetic profiles of more than a
thousand people from 52 places around the world.
Rosenberg:
One thing we found was that the amount of variation across populations was smaller than
we had originally expected and smaller than had been found previously. So the vast
majority of the sites in the genome are identical across all populations.
Nevertheless, those sites could be used to predict that person's ancestry solely based
on their DNA. That's because certain combinations of genetic types were more common
in some regions than in others, and the computer program was powerful enough to tease
those out.
Rosenberg:
This is helpful towards trying to figure out the relationships between different
populations and the patterns of human migration.
So combined with evidence from fields such as archaeology and linguistics, genetics can
help scientists understand human history. For the American Association for the
Advancement of Science, I'm Bob Hirshon.
Making Sense of the Research
Although humans throughout history have made a really big deal over differences in
populations, whether those differences are based on nationality, ethnicity, or skin color,
the fact remains that we're all pretty similar. If you compare any two people to each
other—an Eskimo and a North African, a French woman and a Chinese man—you'll find
that 99.9% of their DNA is identical. In other words, everything that makes you unique
is concentrated in less than one one-thousandth of your genes.
What's more, even within that tiny fraction of DNA that varies between people, the
differences between populations aren't as dramatic as the researchers expected. In
fact, the overwhelming majority of genetic differences between individuals are just as
variable within small populations as they are across the entire world. Comparatively
speaking, only a small handful of genetic signatures are more common in some human
populations than in others.
Nevertheless, the researchers were able to use these tiny slivers of our genetic code to
predict where people came from. They accomplished this by using a powerful computer
program that analyzed hundreds of genetic signatures at once. By looking for patterns
of "microsatellites"—short strings of DNA that are passed down from generation to
generation—the researchers were able to make accurate statistical guesses about
people's ancestries.
So what good is this information? Well, for one thing, it could help out archaeologists
and anthropologists who study the history of human migrations around the globe. But
there's another, more practical use for it. For years, some doctors have been asking
people about their ancestries in order to determine if they're genetically pre-disposed
to certain diseases. But other doctors have argued that the question is useless because
the idea of "ancestry" has no real genetic meaning.
This study suggests that in some cases, where your ancestors came from may in fact
have something to do with the kinds of genes you might be carrying. And that knowledge
may not only help physicians assess an individual patient's risk for a disease, but also
help epidemiologists (scientists who study diseases in populations) understand patterns
of disease around the world.
1. About how similar are human beings genetically?
2. What is the difference between genes that simply vary from person to person, and
genes that are distinctive of populations? Are distinctive genes shared by all members
of a population?
3. What factors allowed the researchers to analyze such subtle variations in human
genetics?
4. Can you think of specific situations in which this knowledge may be used? Give
hypothetical examples for the following situations:

A doctor-patient relationship

An anthropologist studying the history of a population

An epidemiologist studying a rare genetic illness
tHe pUnneTT SquaRE
prACTice PagE
(from Luby’s BioHelp, http://www.borg.com/~lubehawk/psquprac.htm)
On this page is a set of "typical" genetics questions that are best answered using a
Punnett square. Draw a Punnett Square and show your work!
As always, do your best!
P-squARe prActICE QueSTioN #1
Let's say that in seals, the gene for the length of the whiskers has two alleles. The
dominant allele (W) codes long whiskers & the recessive allele (w) codes for short
whiskers.
a) What percentage of offspring would be expected to have short whiskers from
the cross of two long-whiskered seals, one that is homozygous dominant and one
that is heterozygous?
b) If one parent seal is pure long-whiskered and the other is short-whiskered,
what percent of offspring would have short whiskers?
P-squARE PraCTice qUesTiON #2
In purple people eaters, one-horn is dominant and no horns is recessive. Draw a Punnett
Square showing the cross of a purple people eater that is hybrid for horns with a purple
people eater that does not have horns. Summarize the genotypes & phenotypes of the
possible offspring.
p-sqUaRe pRAcTicE QUestiON #3
A green-leafed luboplant (I made this plant up) is crossed with a luboplant with yellowstriped leaves. The cross produces 185 green-leafed luboplants. Summarize the
genotypes & phenotypes of the offspring that would be produced by crossing two of the
green-leafed luboplants obtained from the initial parent plants.
P-squARE PRacTice qUeStION #4
Mendel found that crossing wrinkle-seeded plants with pure round-seeded plants
produced only round-seeded plants. What genotypic & phenotypic ratios can be
expected from a cross of a wrinkle-seeded plant & a plant heterozygous for this trait
(seed appearance)?
Diagram of a Gene
Nectarines
The origin of the fuzzless peach. I'm Bob Hirshon and this is Science Update.
Today's Why Is It? question comes from Karen Hopkin Of Somerville, Massachusetts.
She thought the nectarine was a cross between the peach and the plum. But she was
startled to hear that the nectarine may actually be some sort of mutant peach. She
wants to know what's what.
Well, according to Wayne Sherman, a horticulturist at the University of Florida, the
mutation theory wins out.
Sherman:
A nectarine is a mutation of peach from fuzzy skinned to no fuzzy skinned, or
glaucoused from pubescence.
That means peaches and nectarines essentially have the same genes. A peach tree will
produce peaches if it inherits the dominant, fuzz-producing gene. But it'll make
nectarines if it gets the recessive, or hairless, version of the gene.
And Sherman says the gene does more than produce fuzz.
Sherman:
There are a number of factors that go along with the glaucous skin of the nectarine.
Nectarines generally have more red color in the skin, more rounder shape, smaller size,
more sugars, more acids, and more higher density.
For the American Association for the Advancement of Science, I'm Bob Hirshon.
Making Sense of the Research
Although living things have thousands of genes, it's remarkable what a difference a
single gene can make. In this case, the gene separates peaches from nectarines. As
Sherman explains, it affects not only the skin of the fruit but also its color, shape, size,
and flavor.
This is a classic example of Mendelian genetics at work. Named after Gregor Mendel,
the 19th-century monk who pioneered genetic science, it's a phrase that scientists use
to describe the simplest patterns of genetic inheritance.
Nectarines and peaches demonstrate the pattern of simple dominance. Like people,
animals, and most other living things, nectarine and peach trees have two copies of every
gene—one from each parent. (Yes, plants have parents.) The peach version is dominant
and the nectarine version is recessive.
In simple dominance, as long as one copy of the dominant gene is present, the dominant
trait will be expressed (in other words, it will show up in the living thing). So if you have
even one peach gene, you get a peach tree. You need two copies of the nectarine gene to
get nectarines.
There are other patterns of inheritance besides simple dominance. In incomplete
dominance, if you have one copy of the dominant gene and one of the recessive, the
living thing will be a hybrid that differs from both the pure dominant and pure recessive
version. Many other traits are non-Mendelian, which means that although they are
inherited, they don't follow the simple patterns that Mendel first described.
It's important to note that although nectarines are a mutant version of the peach, that
doesn't mean they're "genetically engineered." Genetically-engineered foods are grown
from plants whose genes were deliberately altered in the laboratory at some point in
time. Nectarines are all-natural mutants that originated in China over 2,000 years ago.
1. What is a nectarine?
2. What does "simple dominance" mean? How does it relate to peaches and nectarines?
3. Which of the following would be possible, and why? Remember that each tree
inherits one copy of the peach/nectarine gene from each parent.
A) Cross two peach trees, get a peach tree (PP x PP or PP x Pp or Pp x Pp)
B) Cross two peach trees, get a nectarine tree (Pp x Pp)
C) Cross a peach and a nectarine tree, get a nectarine tree (PP x pp or Pp x pp)
D) Cross a peach and a nectarine tree, get a peach tree (PP x pp or Pp x pp)
E) Cross two nectarine trees, get a peach tree (pp x pp)
Genetics Practice Problems
(from The Biology Corner – Worksheets and Lessons)
1. For each genotype below, indicate whether it is heterozygous (He) or homozygous
(Ho).
AA _____
Ee ____
Ii _____
Mm _____
Bb _____
ff ____
Jj _____
nn _____
Cc _____
Gg ____
kk _____
oo _____
DD _____
HH ____
LL _____
Pp _____
2. For each of the genotypes below determine what phenotypes would be possible.
Purple flowers are dominant to white
flowers
PP
Pp
pp
Round seeds are dominant to wrinkled
seeds
RR
Rr
rr
Brown eyes are dominant to blue eyes
BB
Bb
Bb
Bobtails in cats are recessive
TT
Tt
tt
3. For each phenotype below, list the genotypes (remember to use the letter of the dominant
trait)
Straight Hair is dominant to curly
____Straight
____Straight
____Curly
Pointed heads are dominant to round heads
____Pointed
____Pointed
____Round
4. Set up the Punnet squares for each of the crosses listed below. Round seeds are
dominant to wrinkled seeds.
Rr x rr
What percentage of the offspring will be round?
_______________
RR x rr
What percentage of the offspring will be round?
_______________
RR x Rr
What percentage of the offspring will be round?
_______________
Rr x Rr
What percentage of the offspring will be round?
_______________
Practice with Crosses. Show all work!
5. A TT (tall) plant is crossed with a tt (short plant).
What percentage of the offspring will be tall? ___________
6. A Tt plant is crossed with a Tt plant.
What percentage of the offspring will be short? ______
7. A heterozygous round seeded plant (Rr) is crossed with a homozygous round seeded
plant (RR).
What percentage of the offspring will be homozygous (RR)? __________
8. A homozygous round seeded plant is crossed with a homozygous wrinkled seeded
plant.
What are the genotypes of the parents? __________ x __________
What percentage of the offspring will also be homozygous? ___________
9. In pea plants purple flowers are dominant to white flowers.
If two white flowered plants are cross, what percentage of their offspring will be
white flowered? ______________
10. A white flowered plant is crossed with a plant that is heterozygous for the trait.
What percentage of the offspring will have purple flowers? ___________
11. Two plants, both heterozygous for the gene that controls flower color are crossed.
What percentage of their offspring will have purple flowers? ____________
What percentage will have white flowers? ___________
12. In guinea pigs, the allele for short hair is dominant.
What genotype would a heterozygous shorthaired guinea pig have? _______
What genotype would a purebreeding shorthaired guinea pig have? _______
What genotype would a longhaired guinea pig have? ________
13. Show the cross for a pure breeding shorthaired guinea pig and a longhaired guinea
pig.
What percentage of the offspring will have short hair? __________
14. Show the cross for two heterozygous guinea pigs.
What percentage of the offspring will have short hair? ________
What percentage of the offspring will have long hair? _______
15. Two shorthaired guinea pigs are mated several times. Out of 100 offspring, 25 of
them have long hair. What are the probable genotypes of the parents?
________ x ___________
Show the cross to prove it!
Genetics With a Smile
(modified from a lesson by T. Trimpe, http://www.sciencespot.com)
Part A: Smiley Face Traits
 Obtain two coins from your teacher. Mark one coin with an “F”
and the other with an “M” to represent each of the parents. The parents are
heterozygous for all the Smiley Face traits.

Flip the coins for parent for each trait. If the coin lands with heads up, it
represents a dominant allele. A coin that lands tails up indicates a recessive allele.
Record the result for each person by circling the correct letter. Use the results
and the Smiley Face Traits page to determine the genotype and phenotype for
each trait.
Trait
Female
Genotype
Male
Face Shape
C
c
C
c
Eye Shape
E
e
E
e
Hair Style
S
s
S
s
Smile
T
t
T
t
Ear Style
V
v
V
v
Nose Color
D
d
D
d
Face Color
Y
y
Y
y
Eye Color
B
b
B
b
Hair Length
L
l
L
l
Freckles
F
f
F
f
Nose Color
R
Y
R
Y
Ear Color
P
T
P
T
Phenotype
Part B: Is it a boy or girl?
To determine the sex of your smiley face, flip the coin for the male parent. Heads would
represent X, while tails would be Y.
Female
Sex
X
Male
X
Genotype
Phenotype
Y
Part C: Create Your Smiley Face!
Use the Smiley Face Traits chart and your results from Part A to create a sketch of
your smiley face in the box. Do this on a separate sheet of paper. Once you have
completed the sketch, use the drawing tools in Microsoft Word to create your smiley
face! Also, remember...

Don’t forget to give your smiley face a name! You will also need to include your
name as parent and your class.
Our Baby _____________________________________
Parents ___________________________________________________________
Genetics with a Smile
Wrapping It Up!
1. How does your smiley face compare to the ones created by your classmates? Pick
two different parents and compare each of the 12 traits. Indicate the phenotype for
each smiley face for each trait in the chart.
Trait
Our Smiley
Face
Smiley Face
by:
Smiley Face
by:
Face Shape
Eye Shape
Hair Style
Smile
Ear Style
Nose Color
Face Color
Eye Color
Hair Length
Freckles
Nose Color
Ear Color
2. Which smiley face has the most dominant traits? _____________________ How
many? ______ traits?
3. Which smiley face has the most recessive traits? _____________________ How
many? ______ traits?
4. What is the probability that a smiley face will have a green face? _____ out of
_____ or ____ %
5. How many smiley faces have a green face, which is a recessive trait? _____ out of
_____ or ____ %
6. How does your predicted probability for a green face (#5) compare to the actual
results (#6)? Explain.
7. What is the probability that a smiley face will have an orange nose? _____ out of
_____ or ____ %
8. How many smiley faces have an orange nose? _____ out of _____ or ____ %
9. Why did you only need to flip the male parent coin to determine the sex of your
smiley face?
10. Uncle Smiley, who is heterozygous for a yellow face, married a woman with a green
face. Both of them have always wanted a large family! If they were to have 12 children,
what is the probability that the children would have yellow faces? How many would have
green faces? Create a Punnett square to help you find your answers.
11. Grandma and Grandpa Smiley are heterozygous for the star eye shape. If one of
their heterozygous children married a girl with blast-type eyes, what percentage of
their grandchildren should have starry eyes? What percent would have blast-type eyes?
Create a Punnett square to help you find your answers.
12. Baby Smiley has curly hair, but neither of her parents do! Is this possible? Create a
Punnett square to help you find your answer.
Bikini Bottom Genetics
(from a worksheet by T. Trimpe 2003 http://sciencespot.net/)
Scientists at Bikini Bottoms have been investigating the genetic makeup of the
organisms in this community. Use the information provided and your knowledge of
genetics to answer each question.
1. For each genotype below, indicate whether it is a heterozygous (He) OR homozygous
(Ho).
TT _____
Dd _____
Bb _____
ff _____
DD _____
Tt _____
Ff _____
bb _____
tt _____
BB _____
dd _____
FF _____
2. Determine the phenotype for each genotype using the information provided about
SpongeBob. Yellow body color is dominant to blue.
YY _________________
yy _________________
Yy _________________
Square shape is dominant to round.
SS _________________
ss _________________
Ss _________________
3. For each phenotype, give the genotypes that are possible for Patrick.
A tall head (T) is dominant to short (t).
Tall = ________________________
Short = __________________________
Pink body color (P) is dominant to yellow (p).
Pink body = ___________________
Yellow body = _____________________
4. SpongeBob SquarePants recently met SpongeSusie Roundpants at a dance. SpongeBob
is heterozygous for his square shape, but SpongeSusie is round. Create a Punnett square
to show the possibilities that would result if SpongeBob and SpongeSusie had children.
HINT: Read question #2!
A. List the possible genotypes and phenotypes for their children.
B. What are the chances of a child with a square shape? ____ out of ____ or ____%
C. What are the chances of a child with a round shape? ____ out of ____ or ____%
5. Patrick met Patti at the dance. Both of them are heterozygous for their pink body
color, which is dominant over a yellow body color. Create a Punnett square to show the
possibilities that would result if Patrick and Patti had children. HINT: Read question
#3!
A. List the possible genotypes and phenotypes for their children.
B. What are the chances of a child with a pink body? ____ out of ____ or ____%
C. What are the chances of a child with a yellow body? ____ out of ____ or ____%
6. Everyone in Squidward’s family has light blue skin, which is the dominant trait
for body color in his hometown of Squid Valley. His family brags that they are a
“purebred” line. He recently married a nice girl who has light green skin, which is
a recessive trait. Create a Punnett square to show the possibilities that would
result if Squidward and his new bride had children. Use B to represent the
dominant gene and b to represent the recessive gene.
A. List the possible genotypes and phenotypes for their children.
B. What are the chances of a child with light blue skin? ____%
C. What are the chances of a child with light green skin? ____%
7. Assume that one of Squidward’s sons, who is heterozygous for the light blue body
color, married a girl that was also heterozygous. Create a Punnett square to show the
possibilities that would result if they had children.
A. List the possible genotypes and phenotypes for their children.
B. What are the chances of a child with light blue skin? ____%
C. What are the chances of a child with light green skin? ____%
8. Mr. Krabbs and his wife recently had a Lil’ Krabby, but it has not been a happy
occasion for them. Mrs. Krabbs has been upset since she first saw her new baby who
had short eyeballs. She claims that the hospital goofed and mixed up her baby with
someone else’s baby. Mr. Krabbs is homozygous for his tall eyeballs, while his wife is
heterozygous for her tall eyeballs. Some members of her family have short eyes, which
is the recessive trait. Create a Punnett square using T for the dominant gene and t for
the recessive one.
A. List the possible genotypes and phenotypes for their children.
B. Did the hospital make a mistake? Explain your answer.
Oompah Loompa Genetics
1. Oompahs generally have blue faces which is caused by a dominant gene. The recessive
condition results in an orange face. Develop a "key" to show the genotypes and
phenotypes possible for Oompa Loompas.
2. Two heterozygous Oompahs are crossed. What proportion of the offspring will have
orange faces?
3. A blue-faced Oompah (homozygous) is married to an orange-faced Oompah. They have
eight children. How many children will have blue faces?
4. Otis Oompah has an orange face and is married to Ona Oompah who has a blue face.
They have 60 children, 31 of them have orange faces. What are the genotypes of the
parents?
5. Odie Oompah has a blue face. In fact, everyone in Odie's family has a blue face, and
the family boasts that it is a "pure" line. Much to his family's horror, he married Ondi
Oompah who "gasp" has an orange face. What are the genotypes of their children? Is
Odie's line still "pure"?
6. Ona Oompah (from#4) divorces Otis and marries Otto. Otto has an orange face.
What is the probability that Ona and Otto's children will have orange faces?
7. Oompahs can have red, blue or purple hair. Purple hair results from the heterozygous
condition. Make a "key" showing the genotypes and phenotypes for hair color. Is this an
example of codominance or incomplete dominance?
8. Orville Oompah has purple hair and is married to Opal Oompah who brags that she has
the bluest hair in the valley. How many of Opal's children will be able to brag about
their blue hair also?
9. Olga Oompah has red hair and marries Oliver Oompah who has blue hair. They have 32
children. What color is their children's hair?
10. Olivia Oompah is married to Odo Oompah and they both have purple hair. What color
hair and in what proportion would you expect their children to have?
12. In the land of Oompah, blue hair is highly valued, blue haired Oompahs even get
special benefits. Oscar Oompah has purple hair but he wants to find a wife that will give
him blue haired children. What color hair should his wife have? What would be his
second choice?