MS-LS3-1 Develop and use a model to describe why structural changes to genes (mutations) located on chromosomes may affect proteins and may result in harmful, beneficial, or neutral effects to the structure and function of the organism. Clarification Statement: Emphasis is on conceptual understanding that changes in genetic material may result in making different proteins.

By the end of grade 8. Genes are located in the chromosomes of cells, with each chromosome pair containing two variants of each of many distinct genes. Each distinct gene chiefly controls the production of a specific protein, which in turn affects the traits of the individual (e.g., human skin color results from the actions of proteins that control the production of the pigment melanin). Changes (mutations) to genes can result in changes to proteins, which can affect the structures and functions of the organism and thereby change traits. Sexual reproduction provides for transmission of genetic information to offspring through egg and sperm cells. These cells, which contain only one chromosome of each parent’s chromosome pair, unite to form a new individual (offspring). Thus, offspring possess one instance of each parent’s chromosome pair (forming a new chromosome pair). Variations of inherited traits between parent and offspring arise from genetic differences that result from the subset of chromosomes (and therefore genes) inherited or (more rarely) from mutations. (Boundary: The stress here is on the impact of gene transmission in reproduction, not the mechanism.)

Evidence Statements

MS-LS3-1

1. Components of the model

   1. Students develop a model in which they identify the relevant components for making sense of a given phenomenon involving the relationship between mutations and the effects on the organism, including:

      1. Genes, located on chromosomes.

      2. Proteins.

      3. Traits of organisms.

2. Relationships

   1. In their model, students describe the relationships between components, including:

      1. Every gene has a certain structure, which determines the structure of a specific set of proteins.

      2. Protein structure influences protein function (e.g., the structure of some blood proteins allows them to attach to oxygen, the structure of a normal digestive protein allows it break down particular food molecules).

      3. Observable organism traits (e.g., structural, functional, behavioral) result from the activity of proteins.

3. Connections

   1. Students use the model to describe that structural changes to genes (i.e., mutations) may result in observable effects at the level of the organism, including why structural changes to genes:

      1. May affect protein structure and function.

      2. May affect how proteins contribute to observable structures and functions in organisms.

      3. May result in trait changes that are beneficial, harmful, or neutral for the organism.

   2. Students use the model to describe that beneficial, neutral, or harmful changes to protein function can cause beneficial, neutral, or harmful changes in the structure and function of organisms.