Download Phenotype - El Camino College

MENDELIAN GENETICS FIELDWORK ASSIGNMENT
Review the Instructions for this assignment before you begin. You’ll need to submit the following four pages to
the instructor by email. DO NOT ALTER THE COLOR OR FONT SIZE OF THE TEXT. When you insert your own
text, use legible, 11-12 point, black or dark blue font.
I. OBSERVATIONS AND RECORDING YOUR DATA
A. Parent Generation Phenotypes


Fill in the names of members of the Parent generation in the top row of the table.
Observe, or interview, each person to determine his/her phenotype for each of the
monogenic traits. Indicate this by filling in dominant or recessive for each one.
TRAITS
Phenotype
Phenotype
Earlobe Attachment
Tongue Rolling
Hitchhiker’s Thumb
Facial Dimples
Big Toe Length
B. Offspring Generation Phenotypes



Fill in the names of the members of the Offspring generation in the top row of the table.
Observe, or interview, each person to determine his/her phenotype for each of the
monogenic traits. Indicate this by filling in dominant or recessive for each one.
If there are more offspring than spaces, create your own table on a separate sheet.
TRAITS
Phenotype
Phenotype
Phenotype
Phenotype
Phenotype
Earlobe Attachment
Tongue Rolling
Hitchhiker’s Thumb
Facial Dimples
Big Toe Length
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II. USING PUNNETT SQUARES TO DETERMINE GENOTYPES
Read all directions carefully before starting this portion of the assignment:

From the tables on the previous page, choose 3 traits for which family members exhibit
variation (i.e. traits for which there are differing phenotypes among the individuals). If
there is no variation, choose any three traits you wish.

Your goal is to try to determine their actual genotypes by using Punnett squares. Fill in the alleles
and genotypes in the squares on the following two pages (in most cases there’s only one correct
answer/square, but three squares are provided in case there’s a scenario with more than one
possibility). List genotypes for each member of each generation in the spaces below. In some
situations, it won’t be possible to determine the actual genotype for a dominant trait - in which
case, you should list the two possible genotypes (e.g. TT and Tt).

Reminder: in a Punnett square, parents go on the outside row and column, and probabilities for
offspring will be in the other four spaces in the square.

Be sure to show your work for each one, even if you already know what the offspring genotypes
are! (Three squares are provided, but you may not need to use them all).

These are autosomal traits, which means males and females inherit them in the same manner.
Don’t use X’s and Y’s in the Punnett Squares!
Fill in names of the traits you select from the tables on the previous page:
TRAIT #1: _________________________
Do your work on a sheet of scratch paper before filling in alleles and genotypes in the spaces below. In
most cases, there’s only one correct answer/square, but several are provided in the event that you have a
scenario with more than one possibility (in that case, show all possible Punnett squares).
X
X
X
Actual genotypes for each member of the:
PARENT GENERATION:
OFFSPRING GENERATION:
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TRAIT #2: _________________________
X
X
X
Actual genotypes for each member of the:
PARENT GENERATION:
OFFSPRING GENERATION:
TRAIT #3: _________________________
X
X
X
Actual genotypes for each member of the:
PARENT GENERATION:
OFFSPRING GENERATION:
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III. REPORT/ANALYSIS
Address each of the questions below (the total length of all your answers should be about 150-200
words). To receive credit, reports must be written in YOUR OWN WORDS (all of it must be original,
based on the data you collected in your observations and interviews). Proper sentence structure and
spelling counts!
1) Briefly explain whom you interviewed/observed, the date(s) of your study, location
and method(s) you used (e.g. by telephone, in person, etc.).
Type your response here:
2a) Look over the data in the tables on page 1. Were dominant or recessive phenotypes
more common in your study sample? (don’t discuss a particular trait, just explain which
type – dominant or recessive - was most common).
Type your response here:
b) Based on your knowledge of Mendelian Genetics (Chapter Four), which type of
phenotype – dominant or recessive - do you think is more likely to occur in higher
frequencies in the human population overall? Explain your answer.
Type your response here:
3a) Why is knowledge of Mendelian inheritance important to a genetics counselor or
other medical professional? Explain.
Type your response here:
b) Is an understanding of Mendelian genetics relevant to you and your family (or your
future family)? Explain.
Type your response here:
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