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BIOLOGY I – PEDIGREE BASICS

HEREDITY - 10

 

BACKGROUND INFORMATION –

Organizing information is often the key to solving a problem.  Tracing hereditary characteristics over many generations using a pedigree will be helpful in organizing a family’s genetic information. This activity will help us to learn how to draw and interpret a pedigree. 

 

            This pedigree traces the trait we call “dimples” through three generations of a family.  Here are some details about the symbolism that are needed to follow a pedigree.  First, generations are indicated by the Roman numeral at the right of each row.  Individuals are numbered left to right across a row for easy identification within the pedigree.  This is needed when names are unavailable, or are not being used for reasons of privacy.  Marriages (or biological parenting) are symbolized by a horizontal line directly connecting two symbols.  In a family, older siblings will be indicated farther left in the pedigree.  Circles are used to indicate females, while squares are males.  Those individuals who have the trait that the pedigree is tracking will be shown as a shaded in symbol.  In this case, those that are shaded have dimples.

 

 

READING A PEDIGREE –

 

            The following passage describes this family.  Use it to write the name of each person below the correct symbol in the pedigree. 

 

Although Jane and Joe Smith have Dimples their daughter, Clarrisa, does not.  Joe’s dad, Jim Smith, has dimples, but his mother, Martha, and his sister, Grace, do not.  Jane’s dad, Kevin Renaldo, her brother, George, and her sister, Emily, do not have dimples, but her mother, Kathy, does.  

 

 

 

MAKING A PEDIGREE –

Draw the pedigree based on the following passage about a family with freckles.  (Better use a pencil!)  Write the name of each family member under their symbol. 

 

Andy, Penny and Delbert have a uni-brow (one continuous eye brow), but their mother, Sally Covington, does not.  Gina Giordano, who is Sally Covington’s sister, has a uni-brow, but her parents, Orville and Olive Lutz, do not.  Deidra and Darlene Giordano both have uni-brows but their sister, Dixie, liker her father does not have uni-brows

 

 

 

FUTHER ANALYSIS OF THIS PEDIGREE –

  1. Carriers of a trait are indicated by a symbol that is half shaded.  Figure out who the carriers are in this family and shade in half of their symbol. 
  2. The passage says nothing about the father of Andy, Penny and Delbert.  What can we tell about him from the information we have about his children?  Did he have a uni-brow or not?

 

 

 

 

 

  1. What advantage does a pedigree have over a family history written as a passage?

 

 

 

 

 

ADVANCED PROBLEM SOLVING WITH A PEDIGREE –

 

 

 

 

  1. Does this trait prevent the individual who has it from reproducing?

 

  1. Which family members have this trait?  (Write down individuals as Roman numeral – number, such as III-4)

 

 

 

 

  1. Which family members are carriers?

 

 

 

 

  1. Is this a dominant or recessive disorder?  Explain why…

 

 

 

 

 

 

  1. Can III-2 and III-3 ever have a child who has this trait?

 

  1. Can II-5 and II-6 ever have a child who does not have this trait?

 

  1. Could I-1 and I-2 ever have had children who did not have the trait and were not even carriers?

 

  1. Could this pedigree be tracking a disease that causes death in early childhood?