Summary
Students will model Mendel’s Law of Segregation and Independent Assortment using Popsicle sticks to represent diploid autosomes and sex chromosomes. By the end of this lesson, students will produce unique paper baby dragons.
Essential Question(s)
What makes individuals unique?
Snapshot
Engage
Students watch a video or look at a picture and identify all of the similarities and differences of dragons.
Explore
Students explore the Laws of Segregation and Independent Assortment of genes through an activity called Dragon Delivery.
Explain
Students jigsaw and why-light an information packet describing Mendel’s Laws, Punnett squares, and various types of traits such as sex-linked, co-dominant, sex-limited, and sex-influenced.
Extend
Students present their dragons to the class along with Punnett Squares for each trait and explain the frequency of their dragon baby’s traits expressed as a proportion and percentage.
Evaluate
Students evaluate each other’s presentations for accuracy using a rubric. Students independently complete a formative assessment titled "Dogs-Puppies so much more."
Materials
Picture of several dragons from Dreamworks movie "How to Train Your Dragon" (or a short video clip showing several dragons from the movie)
Multi-colored Popsicle sticks with alleles printed on both sides (each student will need 1 of each color: green, red, orange, yellow, and either pink or blue for female or male).
Popsicle Sticks Coding (attached; to be printed for popsicle sticks)
Dragon Delivery Activity handout (attached)
Dragon Reading (attached; one copy for every student)
Dragon descriptions for extend/expand
Poster Rubric (attached)
Lesson Slides (optional)
Calculators (optional; one for every pair of students)
Blank paper
Highlighters
Colored pencils, crayons, or markers
Engage
Prior knowledge: Students should be familiar with the terms genes, chromosomes, alleles, dominant, recessive, phenotype, genotype, Punnett squares, diploid, haploid, and gametes. If students do not have this background, then the teacher will want to use these terms in context when helping students with the activity and the reading in the explore and explain phases.
Key Terms for Lesson:
Mendel’s laws:
Law of Segregation: Each parent has two alleles that contribute to the phenotypes and genotype of offspring. These alleles may be dominant or recessive.
Law of Independent Assortment: Different pairs of alleles are passed on to the next generation. This allows for many combinations of alleles and explains how offspring may inherit traits not seen by either parent. This also explains why the human inheritance of a particular eye color does not increase or decrease the likelihood of having 6 fingers on each hand because genes for independently assorted traits are located on different chromosomes.
Punnett squares: This is a simple graphical way of discovering all of the potential combinations of genotypes that can occur in children, given the genotypes of their parents. It also shows us the odds of each of the offspring genotypes occurring.
Sex-linked traits: Characteristics determined by genes located on sex chromosomes.
Co-dominant traits: Both alleles (dominant and recessive) are equally expressed.
Sex-limited traits: A male and a female with the same genotype will express them differently based on their sex, restricted to autosomal traits.
Sex-influenced traits: Restricted to autosomes and are generally influenced by presence of hormones.
Relationship between DNA, chromosome, gene, and alleles: Chromosomes contain DNA. DNA contain genes. Genes contain alleles.
Homozygous: Two alleles are dominant or both recessive.
Heterozygous: One allele is dominant and one allele is recessive.
Dominant: Shown with a capital letter, is usually the expressed allele.
Recessive: Shown with a lowercase letter, and is usually not expressed unless both inherited alleles are recessive or is co-dominant.
Phenotype: Physical expression of genes – what we see.
Genotype: Made of two alleles, one from mother and from father. Example of genotypes: GG (homozygous dominant), Gg (heterozygous), gg (homozygous recessive)
Show students the video clip or project the picture of multiple dragons and ask them to list all of the similarities and differences they observe in the dragons. Ask students to share their responses. Their responses will be describing phenotypes of dragons. Try to elicit this term through questioning. A sample question might be: What is the term we use when describing these physical traits?
Explore
Introduce the activity by telling students they will be surrogate dragon parents. Have students select their partner for the activity; one will need to have the female sex chromosomes (pink/purple Popsicle stick) and one will need to have the male sex chromosomes (blue Popsicle stick).
Give each partner set a copy of the attached Dragon Delivery Activity and two sets of chromosomes with the attached Popsicle Sticks Coding on them (make sure one set has a blue stick and the other set has a pink stick). Ask them to follow the directions carefully and complete the activity.
On separate sheets of paper have students complete Punnett Squares for each trait in the activity. Have them highlight the box that matches their baby dragon’s genotype and next to the box write the ratio and percentage of frequency for their baby.
Have students make a poster that includes their baby dragon drawing and their Punnett Squares, ratios, and percentages. Hang the posters around the room. Have students use the attached Poster Rubric and evaluate one other poster leaving the rubric with that poster.
You may have to explain the rubric so the students have a clear idea of what they are expected to do. Allow each group time to examine the rubric left at their poster and modify anything on their poster.
Explain
Give small groups of students (3-4) a copy of the Dragon Reading. Explain to them how to use Why-Lighting: students highlight what they think is important and then in the margins of the paper, they write why they highlighted that information. This helps students think about why they selected certain information and identify why the information is important. After the reading, have students work with their Dragon Delivery partner to answer the questions on the last page of their Dragon Delivery Activity handout.
Have students swap partners and discuss their answers to the questions. Do this a couple of times before having the original partners come back together. Give students time to change or modify their responses before having a whole class discussion. If you feel the discussions were productive and students developed an understanding, then you may bypass the whole class discussion. If you feel students need the whole class discussion you may want to use the attached Lesson Slides provided to help facilitate this process.
Extend
Give each group a description of another dragon. Ask students to write a claim about how this new dragon may be related to their baby dragon. Students need to write a minimum of five evidence statements supporting their claim.
Have each group share their responses with one other group and get feedback. Give students time to modify their responses based on feedback. Have each group share their final responses with the class.
Evaluate
Have students write a short summary (5 – 7 minute free-write) answering the essential question: What makes individuals unique?
Optional:
Have students individually complete the formative assessment at the end of the Dragon Delivery Activity.
Resources
K20 Center. (n.d.). Why-Lighting. Strategies. https://learn.k20center.ou.edu/strategy/128
Official Clips. (n.d.). How to Train Your Dragon [Video]. https://www.youtube.com/watch?v=-WC9o4Zz-7A&list=PLFB513609A0016440&index=2