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.
What makes individuals unique?
Students will watch a video or look at a picture and identify all of the similarities and differences of dragons.
Students will explore the Laws of Segregation and Independent Assortment of genes through an activity called Dragon Delivery.
Students will 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.
Students will present their dragons to the class along with Punnett Squares for each trait and the frequency of their dragon baby's traits expressed as a proportion and percentage.
Students will evaluate each other's presentations for accuracy using a rubric. Students will independently complete a formative assessment titled "Dogs-Puppies so much more."
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). The alleles for each stick are included on the document called Popsicle sticks.
Handouts for the activity (one for every pair of students), see document titled Dragon Delivery activity
HighlightersHandouts for information packet (one copy for every student), see document titled info packet
Colored pencils, crayons, or markers
Blank paperDragon descriptions for extend/expand.
Formative assessment handout (one for every student), see document titled "Dogs, puppies, and so much more"
Optional: calculators (one for every pair of students)
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:
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 of the dragons. Ask students to share their responses. Their responses will be describing phenotypes of dragons, try to elicit this term through questioning. Sample questions might be: What is the term we use when describing these physical traits?
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 activity and two sets of chromosomes (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 Dragon Delivery Rubric and evaluate one other poster leaving the rubric with that poster.