Pedigree Activity
Ch. 14 Human Genetics
30 points
Goal: Using what you know about genetics and pedigrees, create 2 pedigrees of your family for TWO of
the traits below.
Step 1: Traits Table--Fill in the trait table including you and all of your family members by
questioning your family members to see if they posses the traits. Fill in your chart with detailed
information as you go. Complete this table for as many traits as possible!!
Step 2: Pedigree -- Create a template pedigree chart with your family members on a blank piece of
paper. Your pedigrees must include at least 8 individuals from three generations (if possible).
You MUST include your immediate family (mom, dad, brothers, sisters, and of course yourself)
and then you can fill in with other relatives. These other family members may include
grandparents, aunts, uncles, cousins, etc.
Step 3: Determine Genotypes and Phenotypes -- Each person in each pedigree must be labeled with
a name and a genotype and be colored in correctly. Remember to use the correct symbols and to
color in appropriately for the individual’s genotype.
Remember --Each pedigree must have a title, a key (showing what the shapes mean and also
what shading means) and include whether each trait is dominant or recessive.
You only need to complete TWO pedigree tables. One pedigree per page. Choose traits that
at least two people in your family actually have! If you can not do this than you must see your
teacher!
Checklist:
 Only include one pedigree per page.
 You will have a minimum of 2 pedigrees consisting of 2 Mendelian traits.
 MAKE IT COLORFUL!!!!
 Each pedigree must include the following:
o A title – which is the name of the trait and whether the trait is dominant or recessive.
o
A key (what does a shaded square, shaded circle, open square, open circle mean?)
o
Each person in the pedigree must be labeled with their name and each person interviewed
must have a genotype.
o
If you know someone is showing the dominant trait but you aren’t sure if they are a carrier,
write the dominant allele and a question mark for the second allele (D?). If I can determine
the genotype than you should be able to determine it.
o
If a person appears in your pedigree table, but you did not ask them directly for their traits,
indicate this by writing their name in italicized letters. You should still try to guess their
genotypes based on the information that you have.
Trait Descriptions
Mendelian Traits:
Mid-digital hair
The presence of hair on the second knuckle of the fingers and toes is a dominant trait. This is controlled by a
number of different genes but we will treat it as a one-gene trait. Hair may not be present on all of your
fingers, but if you have hair on even one finger, you show the dominant phenotype.
Widow's Peak
A distinctive downward point in the hairline is known as the widow's peak. This is a dominant trait. If you have a
straight hairline, you have recessive alleles for this trait.
Dimples
A person with dimples have an indentation on either right or left cheek or both. Dimples are dominant over no
dimples.
Unattached Earlobes
A person with attached earlobes will have the lowest point of the earlobe attached to the face. A person with
unattached earlobes will not have the lowest point of the earlobe attached to the face. In fact, you may be
able to put part of your fingertip between the face and the unattached bottom portion of the ear lobe. An
unattached earlobe is the dominant trait.
Hitchhiker's Thumb
The ability to bend the thumb backward (at least 45°) is a caused by a dominant allele. The proper term for
this is distal hyperextensibility. People with dominant alleles have more flexible ligaments and thus looser
joints.
Cheek Freckles
A person who has spots on their cheeks or nose has cheek freckles, these are often found on fair skinned
people. Freckles are controlled by a dominant allele.
Chin Cleft. This trait is controlled by the dominant allele.
Long Second Toe
A person with a long second toe has a second toe that is longer than their big toe. A longer second toe is a
dominant trait.
Tongue Rolling
The ability to roll your tongue into the shape of a tube. People who can roll their tongue have the dominant
trait.
Non-Mendelian Traits – try one of these if you are interested in a challenge!
Hair Texture-- a person can have curly, wavy or straight hair. This trait is inherited through incomplete
dominance. (HH=curly hair, Hh=wavy hair, hh= straight hair)
Blood Type – a person can have type A, type B, type AB or type O blood. (A=iAiA or iAi, B= iBiB or iBi, AB= iAiB,
O= ii)
Color-Blindness – this is an inability to distinguish between specific colors. The most common form is red-green
colorblindness where the individual can not distinguish between red and green colors. There are other, less
common, types of colorblindness. This trait is x-linked. (colorblind =XcY or XcXc, carrier= XCXc, normal
vision=XCY or XCXC)
Hemophilia—an individual with this disorder has difficulty with blood clotting. Any injury can lead to excessive
external or internal bleeding. This is an x-linked trait. (hemophiliac =XhY or XhXh, carrier= XHXh, nonhemophiliac=XHY or XHXH)
Eye Color—Individuals can have blue eyes which are recessive to green eyes which are recessive to brown eyes.
This is an example of multiple alleles. Science can not yet explain eyes that are hazel or change colors.
(Blue=bbgg, Green=bbGG or bbGg, Brown=BBGG, BBGg, BBgg, BbGG, BbGg, Bbgg)
Symbols to create your unique pedigree!
Pedigree Activity Rubric
Name: _________________________________________ Period:_____________
Date:_______________
Pedigree Activity Rubric
This MUST be turned in at the end of the project!
Criteria
Pedigree Chart
Are all family members and relationships
accurate? Are symbols used correctly?
At least 8 people included?
Traits: is the trait
Trait 1:
dominant or receive? did
you include a legend or key?
Are the genotypes correct?
Is there a key for each
Trait 2:
trait? Atleast ONE family
member should have the
chosen trait!
Images
Include an image of the inherited traits?
Organization
Is the project neat and organized? Is it
typed? Are there grammar and spelling
mistakes?
Final Grade
Points
Possibl
e
Points
Earned
Teacher Comments
10
6
6
2
4
60
Grading Scale: student will receive a 0 if the component is missing. Full credit will be earned by
creating a high quality project, not by meeting minimum standards!