Download Toothpick Chromosomes

Primary Type: Lesson Plan
Status: Published
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Resource ID#: 19321
Toothpick Chromosomes
Students will use toothpicks (representing chromosomes) with dots on them (representing genes) to understand how traits are passed from parents
to offspring. They will understand the relationship between genes, chromosomes, and traits.
Subject(s): Science
Grade Level(s): 7
Intended Audience: Educators
Suggested Technology: Document Camera
Instructional Time: 50 Minute(s)
Resource supports reading in content area: Yes
Freely Available: Yes
Keywords: Genes, chromosomes, heredity, traits, genetics
Resource Collection: iCPALMS
ATTACHMENTS
Genetic Cross Diagram.docx
First Generation Answerspea plants.docx
Toothpick Chromosomes Student Directionspea plants.docx
LESSON CONTENT
Lesson Plan Template: Learning Cycle (5E Model)
Learning Objectives: What will students know and be able to do as a result of this lesson?
Students will understand the following concepts:
Every organism has a set of instructions that determines its characteristics.
There are genes located in specific locations on the chromosomes.
Each gene determines a particular trait.
Heredity is the passing of these instructions from one generation to another.
Prior Knowledge: What prior knowledge should students have for this lesson?
SC.4.L.16.1: Identify processes of sexual reproduction in flowering plants, including pollination, fertilization (seed production), seed dispersal, and germination.
SC.6.L.14.2: Investigate and explain the components of the scientific theory of cells (cell theory): all organisms are composed of cells (single-celled or multi-cellular),
all cells come from pre-existing cells, and cells are the basic unit of life.
SC.7.L.16.3: Compare and contrast the general processes of sexual reproduction requiring meiosis and asexual reproduction requiring mitosis.
Guiding Questions: What are the guiding questions for this lesson?
How are traits passed from parents to the children?
If a child looks more like one parent than the other, does that mean that he/she inherited more genes from that parent than the other?
What is a chromosome?
What is a gene?
page 1 of 3 How are genes and chromosomes related?
Engage: What object, event, or questions will the teacher use to trigger the students' curiosity and engage them in the concepts?
Engage the student using the following questions:
How many of you know someone who looks very much like one of their parents?
How many of you have been told, "You look just like your father/mother?"
How many of you can roll your tongue?
How many of you have attached earlobes? Unattached earlobes?
Hold up your thumbs-let's see who has a straight thumb and who has a curved thumb?
When you clasp your hands together interlacing your fingers, do you put your left thumb over your right thumb or your right thumb over your left one?
How do you think characteristics are passed on from parents to the children? If you look more like one parent than the other, do you think you inherited more from
them than the other parent?
Have the students write down their ideas of how characteristics are passed from parents to children in their notebooks.
If you have access to Uncovering Student Ideas in Science Volume 2, page 129 has a great probe called "Baby Mice" that could be used to introduce this lesson as
well.
Explore: What will the students do to explore the concepts and skills being developed through the lesson?
Students will be investigating the connections between chromosomes, genes, and traits that are inherited in a guided inquiry lesson.
Tell the students: You will be modeling how characteristics are passed from parents to offspring in this activity. You will work independently; following the directions
you will be given.
Pass out a bag of toothpicks for each pair of students, the Genetics Cross Diagram and the student directions worksheet. Have the students follow the directions on the
worksheet. The students will be modeling how traits are passed from parents to offspring by using toothpicks which represent chromosomes and the dots on the
toothpicks represent genes. Walk around and observe students as they are working and assist ones who are having difficulty.
Explain: What will the students and teacher do so students have opportunities to clarify their ideas, reach a conclusion or
generalization, and communicate what they know to others?
After students complete the worksheet have a class discussion to clarify their ideas.
Go over these points with the students:
What did the toothpicks represent? What did the dots on the toothpicks represent?
When you crossed the purple and the white flowers and got all purple offspring was it because the offspring only inherited the purple genes? What was the reason?
Where are chromosomes found in a cell? What are chromosomes made of?
Tell students: In your notebooks, look back at what you wrote at the beginning of the lesson about how traits are passed from parents to children. Now write down
what you have learned about the relationships between DNA, chromosomes, genes, and traits: Chromosomes are made of DNA. Sections of the chromosome are
called genes. The genes determine traits in organisms. Heredity is the passing of the traits from one generation to another.
Have students copy a diagram in their notebook similar to the one below to show the relationship between DNA, chromosomes, and genes:
http://www.phoenix5.org/glossary/graphics/CellChromoDNAGene.gif.
Elaborate: What will the students do to apply their conceptual understanding and skills to solve a problem, make a decision,
perform a task, or make sense of new knowledge?
To determine if students have a solid understanding of the concepts, have them create a model to show how they inherited a trait from their parents such as tongue
rolling, attached earlobes, or another of the traits that were discussed at the beginning of the lesson.
Or have them continue to work with the purple and white genes in pea plants and answer these questions:
1. What would be the possible offspring if you crossed a flower with a purple gene and a white one with a flower that had only white genes? Only purple genes?
2. Could two white flowers produce plants with purple flowers? Why or why not?
Summative Assessment
Students could draw a diagram or explain in words the relationship between genes, chromosomes and DNA.
Formative Assessment
If you have access to Uncovering Student Ideas in Science Volume 2 Page Keeley (Author), Francis Eberle (Author), Lynn Farrin (Author), page 129 has a great probe
called Baby Mice that could be used to introduce this lesson. The teacher can use information gathered during the probe to see how students are progressing in their
understanding during the lesson.
Feedback to Students
Teacher monitors group progress giving feedback during the lesson.
ACCOMMODATIONS & RECOMMENDATIONS
Accommodations:
If most students in the class would have a hard time following directions on the worksheet independently, you could do this as a teacher directed inquiry instead. If you
have a few students with special needs, pair them up with students who can assist them reading and completing the worksheet.
Extensions:
Make new sets of toothpicks to represent other traits such as the ones Mendel used in his pea plant experiments. Evaluate students' understanding of the concepts
page 2 of 3 using the different traits.
Suggested Technology: Document Camera
Special Materials Needed:
Use flat toothpicks and a fine-tipped purple marker to make a dot on the toothpicks. Use liquid white-out for the white dots. Place the dots in the same general location
on all the toothpicks to model how the genes are in a certain location on the chromosome. Make 16 toothpicks of each color dot for every pair of students. Store the
toothpicks in a plastic bag.
Make copies of the student handout and the Genetics Cross Diagram, which are located in the Lesson Handouts Section. For durability, laminate the Genetics Cross
Diagram. You will need one handout and one Genetics Cross Diagram for each pair of students.
Make copies of the first and second generation answers and place in separate envelopes which are labeled "first generation answers" and "second generation
answers" on a table near the student groups. For the second generation answers you could also make a copy of a Genetics Cross Diagram and draw on it the correct
arrangement of the toothpicks.
Further Recommendations:
Do this activity as an introduction to how traits are inherited before you discuss Mendel's experiments or Punnett squares.
Additional Information/Instructions
By Author/Submitter
This lesson was adapted from an article in Science Scope, April 2003 called "Toothpick Chromosomes". It has information about extending the lesson to teaching about blood
types, sex-linked traits, and Punnett squares.
SOURCE AND ACCESS INFORMATION
Name of Author/Source: Anonymously Submitted
Is this Resource freely Available? Yes
Access Privileges: Public
License: CPALMS License - no distribution - non commercial
Related Standards
Name
SC.7.L.16.1:
Description
Understand and explain that every organism requires a set of instructions that specifies its traits, that this hereditary
information (DNA) contains genes located in the chromosomes of each cell, and that heredity is the passage of these
instructions from one generation to another.
Remarks/Examples:
Integrate HE.7.C.1.4. Describe how heredity can affect personal health.
page 3 of 3