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Inheritance and Adaptations

During this CELL, students will conduct several investigations focused on the inheritance of genetic information and the expression of traits. By conducting experiments, investigating different variables, and utilizing formulas, students will begin to draw conclusions concerning the relationship between the inheritance and expression of genes and the ability of organisms to adapt, grow, and reproduce in their environment.

Students will explore the science of genetics in a number of different ways in this CELL. Students will be presented with an overall, organizational framework that provides a basis for understanding the relationship between alleles, genes, chromosomes, cells, tissues, and organs. With this in mind, they will begin their exploration of genetics by discovering the location of genetic information, DNA, in the cells of an onion. Through a simple extraction procedure, students will have an opportunity to visualize a cluster of several billion molecules of DNA. In a follow-up investigation, students will also conduct several genetic crosses to examine how genes and traits are inherited by offspring through dominant allele inheritance, recessive allele inheritance, incomplete dominance, and co-dominance. Students will also examine how a cell reads and translates the genetic code to create proteins. Through simple exercises, students will discover that a mutation, or mistake, in the genetic code can alter the function of a protein. Students will then use a model to test the effects of natural selection on a population of organisms over time. In the Performance Assessment, students will have an opportunity to apply their knowledge from this CELL, to create a plan to propagate an endangered species of plants and evaluate the surviving population of this plant over a three-year time period.

By the conclusion of this CELL, students should realize that genetic information is found in the nucleus of a cell. This information is translated into proteins that carry out all functions of a cell. Students will come to realize the relationships between structure and function at the cellular and tissue level by understanding that different proteins carry out different functions in different cells. Students learn that through inheritance, different combinations of alleles result in the specific expression of a trait. The high level of biological variation found in humans is due to the large number of allelic combinations that can result from sexual reproduction. It is this high level of biological variation that results in individuals with unique characteristics. The natural selection of advantageous traits over disadvantageous traits will also contribute to population variation among living things.

Through performing experiments and participating in class discussions, students will begin to comprehend that all of their unique characteristics are a result of the inheritance of genes. This CELL will promote students’ awareness of inheritance and adaptations that they encounter in their daily lives, building continuity between classroom investigations and daily applications.

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Investigation 1: Extracting DNA from a Cell

Investigation One introduces students to the science of genetics. Through observation and experimentation, students will learn that DNA is located in the nucleus of a cell. Students will use a procedure that combines many techniques that scientists may use for DNA extraction to extract DNA from the cells of an onion. Their observations will enable them to realize that one individual molecule of DNA cannot be seen by the naked eye or by a compound microscope from the lab.

Investigation 1: Teacher’s Video (12:07)

Investigation 1: Student’s Video (19:25)

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Investigation 2: The Inheritance of Traits

In Investigation Two, students will examine dominant and recessive alleles. Students will use a model to perform several genetic crosses to determine the allele combinations inherited by offspring. The crosses will be between organisms that possess either dominant alleles, recessive alleles, or both types of alleles. Students will discover that different combinations of dominant and recessive alleles will result in a specific expression of a trait.

Investigation 2: Teacher’s Video (9:09)

Investigation 2: Student’s Video (12:56)

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Investigation 3: Incomplete and Co-Dominance

During Investigation Three, students examine genetic traits that are found on the human face. Students will select allele pairs for several facial traits and then analyze the alleles that were selected to draw a picture of a human face. Through their experiment, students will discern that some traits found on the face display incomplete dominance. They will also come to realize that the high level of biological variation found in the human face will result in the unique appearance of each face that is drawn.

Investigation 3: Teacher’s Video (7:45)

Investigation 3: Student’s Video (7:59)

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Investigation 4: Deciphering the Genetic Code

Investigation Four gives students an opportunity to construct a protein using a set of “RNA” instructions and then test whether their protein will be able to perform its function. Students will also decode a sequence of nucleotides. Students will discover how a cell deciphers the genetic information found in the nucleus to create proteins. Their observations will enable them to realize that a mutation, or mistake, in a sequence of nucleotides may change the translation of the sequence but will not always change whether that sequence can be read by a cell.

Investigation 4: Teacher’s Video (17:10)

Investigation 4: Student’s Video (10:58)

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Investigation 5: Genes and Natural Selection

In Investigation Five, students will use a model to test the effects of natural selection on a population of beetles over a three-year time period. Students will perform a simple test that will demonstrate camouflage to be an advantageous trait. By observation and experimentation, students will come to the understanding that the better-camouflaged beetles will have a higher survival rate than beetles that are not well camouflaged.

Investigation 5: Teacher’s Video (11:35)