Lesson 3 : Monohybrid Crosses
WHAT IS A MONOHYBRID CROSS?
A monohybrid cross is a genetic cross which demonstrates the transmission of a single trait (made of two alleles) from both parents to offspring's. A monohybrid cross can be used to estimate the probability of an offspring carrying that particular trait.
MINDS ON:
Figure 9B
This minds on activity demonstrates to students through inquiry, how well punnett squares predict actual ratios, when determining the transmission of a single gene. Students first go through the theoretical process of constructing a punnett square, and determining the probability of the offspring's having a short big toe versus a long big toe. Once the theoretical is completed, students get to use pennies, where one penny represents the genotype of one of the parents, to resolve through experimentation how many offspring's will display variations in the trait. After, student's have the opportunity to compare their theoretical to their experimental results, to understand the purpose and function of a punnett square in determining the transmission of a single trait. Students must know concepts such as dominant, recessive, alleles, homozygous and heterozygous. This activity allows students to further explore these topics.
PEDEGOGY:
Mendel's Pea Plant Walk through: This worksheet takes students on a journey of how Mendel used pea plants to determine patterns in inheritance. It goes through how Mendel came up with the laws of genetics, and how genetic crosses can be used to predict the probable outcomes of offspring's using the genotypes of the parents. Students also get to simulate how alleles or variation in traits are passed on to offspring using monohybrid crosses.
After completion of the activity, A SMART board, PowerPoint, or prezi can be used to internalize information learned during this lesson. Material to go over includes the law of segregation (which is discussed in the Mendel pea plant walk though), heterozygous traits, and homozygous traits in determining the phenotype of the offspring, and the use of them in monohybrid crosses.
After completion of the activity, A SMART board, PowerPoint, or prezi can be used to internalize information learned during this lesson. Material to go over includes the law of segregation (which is discussed in the Mendel pea plant walk though), heterozygous traits, and homozygous traits in determining the phenotype of the offspring, and the use of them in monohybrid crosses.
CONSOLIDATION:
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This video provides students with a crash course overview on heredity. It goes over what everyone thought heredity use to be, and how Mendel found these patterns in inheritance. It also discusses concepts such as chromosomes, genotype, phenotype, genes, alleles, gametes, homozygous, heterozygous, punnett squares, and monohybrid crosses. The brothers discuss these topics in a way that relates to students, which allows students to have fun and be interest while learning. A worksheet can be provided during this video if a teacher would like students to pick up on certain information or for note taking reasons.
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Exit cards: Students need to finish the questions on the exit split in order to leave the class. This is a great way to get student feedback and to assess if they understood the material. A sample exit card in displayed below.
Figure 10B
