Performance Expectation 

Each standard contains a performance expectation that details how students can perform to show what they’ve learned. It describes what students can do, as opposed to what they understand.

In HS-LS1-1, the first thing we need to consider is that this standard asks students to “Construct an explanation based on evidence”. This tell us that students will need to seek evidence from a phenomena that gives them information about the relationship between DNA, proteins, and the functions of specialized cells. It’s also important to note that the Assessment Boundary does not require students to identify proteins or specific cells, but instead intends for students to be able to clearly discuss this relationship between the structure of DNA and their impact on proteins and cellular function. 

Examples could include changes in the function of proteins with mutations, the proteins generated in cells with the same DNA, but vastly different expressions of the DNA and functions, or the ways that cancer cells impact the expression of DNA/Proteins and the overall function of a cell. 

The Three-Dimensions

1. The SEP for this performance expectation is constructing explanations and designing solutions, and more specifically, students are asked to construct an explanation from valid and reliable evidence.
2. There are two elements of the DCIs. Students must systems of specialized cells are responsible for the essential functions of life and that DNA structure leads to protein structure, and that proteins do most of the work of cells. For example, different organisms with different colorations may have nearly identical DNA, but with slight differences in the DNA that code for the pteridines that lead to differences in animal coloration.
3. Finally, the Cross-Cutting Concept in this PE is Structure and Function. Students must seek to examine the properties of materials (i.e. DNA nucleotide sequences) to draw connections to it’s function (i.e. the proteins synthesized the the function of those proteins). 

The Goals

By the end of a lesson that covers this standard, students should achieve the following milestones: 

1. 1. Understand that there are specialized systems of cells that carry our functions in living systems. 
   2. Be able to link their understanding of the structure of DNA to the functions of proteins and thus the function of a cell. 
   3. Cite and find evidence from information given in a phenomena to show that the link between cell functions and protein. 
   4. Connect that evidence to a claim about the functions of cells and the role of DNA and proteins to the function of the specific phenomena given to students. 

Here are 3 different phenomena where students can apply their understanding of DNA and protein function to assess students or teach students about HS-LS1-1:

1. Students can examine and explain how DNA structures and proteins lead to defective chloride channels in cells and thick mucus production in organs in Cystic Fibrosis. 
2. Students can look at the differences in traits across a population of poison dart frogs. Specifically, how these frogs can have similar DNA, but the slight differences in their DNA leads to different proteins being synthesized with dramatically different colorations and phenotypes. 
3. Students could also look at albinism and the impact that genetic mutations can have on on melanin production.

Student Activity for Assessment of HS-LS1-1

Poison dart frogs are often considered Earth’s most toxic, or poisonous, species. The poison dart frog has enough poison in its system to kill 20,000 mice. They live in Central and South American regions where there is a humid climate, especially the Amazon Rainforest.

What is extremely unique about this species is that they can have a variety of colors. Some of these frogs are yellow, green, blue, orange, and even purple. So, what allows these frogs to have such different colors if they are all the same species?

Figure 1: Chart showing factors that lead to poison dart frogs having varied skin colors.

NGSS Assessment Questions for HS-LS1-1 that scaffold students into making sense of this phenomena:

To assess students understanding of the DCI LS1.A: Structure and Function we can ask them:
1. What structures in poisonous dart frogs dictate what their skin color will be?

Answer: The nitrogenous bases in DNA that code for proteins that dictate skin color.

To assess whether students can apply their understanding of the DCI LS1.A: Structure and Function along with the CCC Structure and Function: 

2. Explain how the protein structures in these poison dart frogs play a role in determining the frogs’ skin color.

Answer: The amino acid sequence in proteins is what gives them their shape. Different amino acid sequences will give organisms different traits. The structure of these proteins is what ultimately contributes to the function of the protein in expressing certain traits like a frog’s skin color which can be varied.

To assess whether students can apply their understanding of the DCI LS1.A: Structure and Function through the lens of the SEP Constructing Explanations and the CCC of Structure and Function:

3. Cite evidence from the model given in Figure 1. Describe what changes occurred to make the frog have green skin as opposed to blue skin.

Answer: One of the nitrogenous bases in DNA changed for the frogs. Where a T (Thymine) is in the DNA of the green frog, there is a C (Cytosine) for the blue frog. This simple difference caused a different amino acid to be coded for both frogs which leads to them having different skin color.