Reproduction

Reproduction 14: Advising Joe

Students return to Joe’s story and develop a written email explaining his situation and a recommendation about what he might do. This activity provides more information about Marfan syndrome and also allows students to consider further how a diagnosis of a genetic condition might affect a person.

Reproduction 13: Fault in the Genes

Students return to their three-dimensional protein models to begin investigating the cause-and-effect relationship between mutations and protein structure and function. The activity begins with a game that introduces students to different types of mutations: deletions, additions, and substitutions. Students then make predictions about how different mutations may affect their protein structures. Using the coated wires and chenille stems, students model the mutations and the resulting changes to their protein structure. After investigating different types of mutations, students construct an explanation for how a mutation in a gene leads to changes in body function, specifically how a mutation in the fibrillin gene leads to Marfan syndrome symptoms.

Reproduction 12: How Do Genes Produce Traits?

This activity introduces the concept that a gene encodes for a protein, which has a specific structure essential to its function in the cell. These protein functions manifest as traits in the body. Students use a coated wire and chenille stems to model and generate explanations for how a gene’s DNA sequence codes for a protein sequence. They continue using this model to explore how the protein sequence determines the protein structure and function. As students model structure and function, they also examine cause-and-effect relationships between gene sequence and protein function.

Reproduction 11: Plant - Animal Interactions

Students read about four different flowers, making note of some traits that may be important in pollination, like color, shape, size, and odor. Then they read about four different animal pollinators and develop an argument based on evidence in the reading for which of the four animals pollinates each of the four flowers. Students obtain information about flower pollination and its importance to plant reproduction. They consider a number of adaptive plant structures and traits that attract animal pollinators. Students construct an argument for which kinds of pollinators are associated with different flower types. By looking for patterns among plant–animal interactions, students develop arguments for how these traits cause the individual plant to have a higher reproductive success than those with different traits. Students add to their arguments by matching four different scents with the flowers and their pollinators.

Reproduction 10: Animal Behavior

Students analyze and interpret data to create arguments that explain behavioral and other traits in animals that at first glance seem to be either neutral or perhaps even harmful. By looking for patterns in the data, students develop arguments about how these traits cause the individual to have higher reproductive success than those with different traits.Students read one of four real-life case studies on a behavioral or physical trait in an animal. They examine and interpret graphs portraying data that relate directly or indirectly to the animals’ reproductive success. Student groups must present and defend their arguments based on evidence to the rest of the class. In the Analysis, students consider which of the animal traits they examined are likely to be influenced primarily by genetics, the environment, or a combination of both.

Reproduction 9: Breeding Critters - More Traits

Students modeled the diversity of offspring possible from two parent critters and discover patterns of inheritance other than strict dominant/recessive traits. The students first looked at pictures of grandparent critters with homozygous genotypes, which bread to have offspring with all heterozygous genotypes. The students looked at the traits of the offspring to determine which alleles for traits were dominant and which were recessive. Several traits did not follow this Mendelian pattern though and instead were examples of incomplete dominance, codominance or traits affected by environmental factors. The students worked in pairs and each modeled parents with all heterozygous genotypes then used coin flips to determine which alleles they would pass down to their offspring. After determining the traits of their offspring critters, they built models of their critter pups.

Grandparent critters Skye and Poppy who are homozygous for all traits.

Parent critter Lucy and Ocean who are heterozygous for all traits.

Reproduction 8: Show Me the Genes

In this activity, students obtain information from a reading that introduces the location of genes on chromosomes and the number of sets of chromosomes in sex cells and the rest of the body. Students use the Stop to Think strategy as they read about the location of genes on chromosomes and the behavior of chromosomes during sexual reproduction. They relate the behavior of genes and chromosomes to explain basic patterns of inheritance. Students are also introduced to the function of DNA and the effects of randomly occurring mutations. This information helps explain some of the phenomena related to genes that students have been learning about, and also prepares them for future activities where they will model the cause-and-effect relationships between genes (and mutations) and protein structure and function.

Below are some YouTube videos for students who want to learn more details about mitosis (body cell division) and meiosis (sex cell division):

Reproduction 7: Do Genes Determine Everything?

In this activity students learn about two traits for seedling color in Nicotiana plants. They examined the family tree of the Nicotiana seeds and determined the genotypes of the parent and grandparent plants, before predicting the expected ratio of dominant green seedlings to recessive yellow seedlings. Students then discuss experimental design before they plan and conduct an investigation to determine how a selected environmental factor (light availability) affects the phenotype of plant seedlings. When the seed sprout in 7-10 days, students will analyze their data to explain the interaction between genetic and environmental factors. They will use this experience as the basis for a discussion of the interplay of genetic and environmental factors in determining traits in humans, as well as in plants.

Students then watched an episode of the PBS program Nova which introduces the concept of the epigenome. Students learn that in addition to the DNA sequence of gene, environmental factors can influence how and when genes are turned on and off.

Reproduction 6: Mendel, First Geneticist

A reading on Gregor Mendel’s investigations and the principles of genetics he identified through his work provides a perspective on the history and nature of science and the data analysis, recognition of patterns, and use of mathematics central to this important advancement in explaining how genes cause traits. The reading provides data from Mendel’s experiments breeding pea plants and his application of ratios to his analysis and interpretation of his results. Students can compare Mendel’s findings, analysis, and model to their own work with the critter model.

Reproduction 5: Gene Squares

This activity introduces the use of Punnett squares as a model for predicting the ratios of both genotypes and phenotypes in the offspring of genetic crosses. Students use crosscutting concepts of patterns and cause and effect as they use Punnett squares to predict outcomes of crosses of various pairs of critters.

Reproduction 4: Gene Combo

Students model the inheritance of single-gene traits by collecting and analyzing data from coin tosses for critter tail color. They discuss the differences between predicted and actual results of probabilistic events and the strengths and weaknesses of the coin-tossing model, develop simple rules for genetic transmission, and reevaluate the hypotheses and models developed in the “Creature Features” activity.

Reproduction 3: Reproduction

In this activity, students engage in the practice of obtaining information as they read about the cellular basis of sexual and asexual reproduction. Differences between the two prepare students to understand the mechanisms of heredity in sexually reproducing organisms.This information will help them to revise their models and explanations for the inheritance of traits and prepare them for quantitative predictions of the incidence of traits in offspring.

Reproduction 2: Creature Features

In this activity, students read about an imaginary breeding scenario. Stop to Think questions prompt them to develop hypotheses to explain the results of genetic crosses in a story about zoo scientists breeding imaginary creatures. They use models to evaluate how well the hypotheses fit additional evidence about the critter offspring. Students begin to use the practice of developing and using models to show and revise their ideas about genes and inheritance of traits as they read about and develop tentative explanations for an imaginary scenario in which animals are bred to produce two generations of offspring. This activity begins a sequence in which students explore core ideas and concepts related to patterns of inheritance of traits and cause-and-effect relationships between genes and traits as a result of sexual reproduction. Students also begin to engage in scientific argumentation as they evaluate possible hypotheses.

Reproduction 1: Joe’s Situation

This activity introduces the fictional scenario of Joe, who has learned that he might have a genetic condition. They generate questions they would have if they were in this situation. Students then view a video produced by the National Marfan Foundation to seek answers to their questions and develop new questions. They also consider the impact of Marfan syndrome on a person’s life. Students engage in the practices of asking questions and obtaining, gathering, and communicating information as they attempt to understand Joe’s story. As they do this, they explore both the causes and effects of a genetic condition, beginning a focus on the crosscutting concepts of cause and effect and structure and function, which run throughout the unit. As students move through the unit, they apply what they learn to Joe’s story. In the final activity of the unit, they make a recommendation to Joe.