How does a pedigree help us to trace a trait that is inherited?

Nakita McNeil

Independence High School, Manhattan

 

Summer Research Program for Science Teachers

Summer 2008

Objective: Students will be able to analyze genetic (basic) patterns to determine dominant or recessive inheritance, summarize examples of dominant and recessive disorders, and construct a human pedigree from genetic information.  

Time: 1-2 class sessions

 

1.Do Now: Face a partner. Observe your partner.

 

                   List features about you partner that makes them different.

                  

Ask students:

                   Are we all the same? Where do traits come from?

 

2. Vocabulary:

 

                   Inheritance

                   Trait

                   Heredity                                                     

 

3. LESSON

 

Brainstorm, and ask students: What are some traits that are passed down in their family’s lineage?

(Students must remember that certain characteristics about a person [weight] can be altered by environmental factors and should not be placed in the heredity column).

 

4. Teacher lead instruction (demonstrate)

 

Teacher: How many of you (students) can role your tongue?

Being able to role you tongue is a dominant expression of a gene. “It shows”

 

 

 

Teacher: How many of you (students) have a hitchhikers thumb?

Hitchhikers thumb is a recessive (hidden) expression of a gene

 

 

 

 

Teacher: How many students have a widow’s peak?

Widows peak is a dominant (shown) expression of a gene.

 

 

 

 

 

Teacher: How many students have connected earlobes?

Free earlobes are a dominant expression of a gene.

 

 

 

 

Have your students test their partner again now that they know some basics traits

               Trait

      You

       YES

 

        NO

  Your partner

        YES

 

          NO

Are you Female?

 

 

 

 

 

Are you Right Handed?

 

 

 

 

 

Do you handclasp with your right thumb on top?

 

 

 

 

 

Do you have Attached Ear lobes?

 

 

 

 

 

Can you roll your tongue?

 

 

 

 

 

Do you have a Widow's Peak?

 

 

 

 

 

Do you have a Cleft Chin?

 

 

 

 

 

Do you have a Hitch Hiker's Thumb?

 

 

 

 

 

Do you have Cheek Dimples?

 

 

 

 

 

 

5.

                                      Anticipation Guide

 

Directions: For each of the following questions state if you agree or disagree and tell why.

 
    1. If you are a girl, you inherit more from your mother.
    2. If your parents can both roll their tongues, you will certainly be able to roll your tongue.
    3. A parent may give a trait to his child without ever having the trait himself.
      4.
    4. If you are injured (hurt) in an accident, you may pass it on to your children.
    5. If you look more like one parent than the other, you inherited more from that parent.
      6.
    6. At birth, you have all the hereditary traits you are ever going to have.

 

6. Ask: Are there any traits that you are sure you inherited from your parents?

 

Trait

Who you inherited it from

Eye color, shape, size

Mother

Hair texture

Grandfather

 

 

7. Look at the following pedigree that shows my relationship to other members of my family.

List 3 things you can learn about my family by looking at this chart. (I have chosen to put stars in the shapes that are affected, because I want to first emphasize male vs. female, then redraw shaded vs. not shaded)

 

 

 

Realize all males are in blue (square) and all females (circle) are in pink. Those with stars have a widows peak.

 

Symbols (for teacher) (DO NOT introduce all symbols to students – KEEP IT SIMPLE):

 

                                                         

 

When introducing the pedigree chart establish:

 

  1. the symbols that are used in pedigrees.
  2. words used to describe basic family relationships.
  3. definitions of key words (see vocabulary list).
  4. that vertical lines distinguish ‘generations’. (For example: old vs. young, past vs. present)
  5. that horizontal lines represent the same ‘generation’.
  6. the difference between a relative and an ancestor.

 

Vocabulary:

 

  • Trait
  • Inherited
  • Heredity
  • Pedigree
  • Generation
  • Relative
  • Ancestor

Relationships:

 

  • Grandmother/ma
  • Grandfather/pa
  • Mother/ma/mom
  • Father/dad/pa
  • Brother
  • Sister
  • Son
  • Daughter
  • Grandson
  • Granddaughter
  • Cousin
  • Nephew
  • Niece
  • Husband
  • Wife

In-Laws (Marriage)

 

  • Mother-in-law
  • Father-in-law
  • Son-in-law
  • Daughter-in-law
  • Brother-in-law
  • Sister-in-law

Step

 

  • Stepmother
  • Stepfather
  • Stepson
  • Stepdaughter
  • Stepbrother
  • Stepsister

 

 

HOMEWORK: DRAW A SIMPLE PEDIGREE OF YOUR FAMILY AND TRACE A TRAIT THAT FLOWS THROUGHOUT. NO LESS THAN THREE GENERATIONS, SHADE IN ALL THOSE WHO HAVE THE TRAIT. FOLLOW THE PEDIGREE KEY GIVEN IN CLASS. BE PREPARED TO SHARE AND TO DISSECT A MORE COMPLICATED PEDIGREE TOMORROW.


STANDARDS:

 

New York State Science Learning Standards; Living Environment

Standard 1

Key Idea 1

1.2a Inquiry involves asking questions and locating, interpreting, and processing

information from a variety of sources.

1.2b Inquiry involves making judgments about the reliability of the source and

relevance of information.

 

Standard 4

Key idea 2

2.1b Every organism requires a set of coded instructions for specifying its traits. For offspring to resemble their parents, there must be a reliable way to transfer information from one generation to the next. Heredity is the passage of these instructions from one

generation to another.

2.1c Hereditary information is contained in genes, located in the chromosomes of each cell. An inherited trait of an individual can be determined by one or by many genes, and a single gene can influence more than one trait. A human cell contains many thousands

of different genes in its nucleus.

Key idea 3

3.1b New inheritable characteristics can result from new combinations of existing genes or from mutations of genes in reproductive cells.

Key Idea 5

5.2h Disease may also be caused by inheritance, toxic substances, poor nutrition, organ malfunction, and some personal behavior. Some effects show up right away; others may not show up for many years.

 

National Science Education Standards

Content Standard A, Abilities to do scientific inquiry, Understandings about scientific inquiry

Content Std C, The cell, The molecular basis of heredity, matter energy organization in living systems