Title: Model Mendelian genetics and the inheritance of traits
Principle(s) Investigated: Mendelian genetics and inheritance of traits.
7.2.b - Students know sexual reproduction produces offspring that inherit half their genes from each parent.
7.2.d - Students know plant and animal cells contain many thousands of different genes and typically have two copies of every gene. The two copies (or alleles) of the gene may or may not be identical, and one may be dominant in determining the phenotype while the other is recessive.
7.7.c - Communicate the logical connection among hypotheses, science concepts, tests conducted, data collected, and conclusions drawn from the scientific evidence.
7.7.d - Construct scale models, maps, and appropriately labeled diagrams to communicate scientific knowledge 9e.g., motion of Earth's plates and cell structure).
Materials:
Each group of 4 students receives:
Procedure:
Student prior knowledge:
Explanation:
This lesson should follow an initial introduction to Mendelian genetics. Begin the lesson with a review of key vocabulary and concepts. Students should recall that parents give half of their genes to their offspring through meiosis. Since each parent gives a set of their genes to their offspring, the offspring will have two different versions of the same gene (homologous pairs). The different versions of a gene are called alleles. For this lesson, dominant alleles will have "complete dominance" rather than incomplete or co-dominant traits. Complete dominance occurs when a genotype with a dominant allele (uppercase letter) would complete mask the recessive allele. The labeling and flipping of the coins reinforces the complete randomness of inherited traits, and that our characteristics are based completely on chance, just like a coin toss.
Questions & Answers:
Q: Could an offspring have traits neither of its parents has?
A: Yes. If both parents have a dominant and a recessive allele of a trait (i.e. Rr = red), it is possible for the offspring to inherit the recessive allele of both parents (rr) and exhibit the recessive trait (green).
Q: If one of the parents was homozygous dominant, as in the case of its nose color (BB) and the other was heterozygous (Bb), could the offspring have traits neither of its parents has?
A: No. In order to have recessive traits, the offspring would have needed to inherit recessive alleles from both parents.
Q: How is the inheritance of traits in these Space Bugs like the inheritance of traits in humans, and how are they different?
A: In both the Space Bugs and humans, traits are influenced by the copies of the parents' alleles. However, human trait inheritance is more complicated in that many of our traits are influenced by many multiple genes as well as the environment.
Applications to Everyday Life:
Photographs:
Videos:
A Beginner's Guide to Punnett Squares-YouTube: http://www.youtube.com/watch?v=Y1PCwxUDTl8&feature=related
Genetics 101 Part 1-What are Genes-You Tube: http://www.youtube.com/watch?v=eOvMNOMRRm8&feature=youtu.be
Genetics 101 Part 3-Where do your genes come from?-You Tube: http://www.youtube.com/watch?v=-Yg89GY61DE&feature=relmfu
Genetics 101 Part 4-What are Phenotypes-You Tube: http://www.youtube.com/watch?v=kLpr6t4-eLI&feature=relmfu
Credits: HOLT California - Life Science