MS-LS3-1: Modeling How Mutations Can Change Proteins and Traits
In plain English: MS-LS3-1 is the NGSS middle school performance expectation that asks students to develop and use a model of why a change to a gene on a chromosome (a mutation) may change the protein the gene codes for, with harmful, beneficial or neutral effects on the organism. It is usually taught in grade 7 or 8 life science.
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.
Assessment Boundary: Assessment does not include specific changes at the molecular level, mechanisms for protein synthesis, or specific types of mutations.
Next Generation Science Standards · Disciplinary Core Idea: Heredity: Inheritance and Variation of Traits · Official standard
Students build and use a model of why a mutation, a change in the structure of a gene on a chromosome, may change the protein that the gene codes for, and why that change may be harmful, beneficial or neutral for the organism. The model has four links: gene, protein shape, the structure or function of the organism, and the effect. Students apply it to corn seedlings that cannot make chlorophyll, monarch caterpillars that can eat poisonous milkweed, bean seeds whose changed protein still works, and beetles whose wings matter differently on an island and on the mainland. All organisms are plants, animals or fictional species, and all data sets are invented for teaching.
The NGSS Clarification Statement says: "Emphasis is on conceptual understanding that changes in genetic material may result in making different proteins." The Assessment Boundary says: "Assessment does not include specific changes at the molecular level, mechanisms for protein synthesis, or specific types of mutations." So the lesson treats a gene as a set of instructions and a protein as a shape that does a job; it does not name kinds of mutations or describe how cells build proteins. Students do the practice of developing and using models: they build physical and drawn models, use them to predict effects and revise them with evidence.
Learning Objectives
By the end of this lesson, students will be able to:
Describe how chromosomes, genes and proteins are related, using a model
Use a model to explain why a mutation may change a protein's shape and so its job, or may leave the protein working the same
Classify the effect of a mutation on an organism's structure and function as harmful, beneficial or neutral, using evidence
Explain with data why the same mutation can be harmful in one environment and beneficial in another
Prior Knowledge Required
Students should already be comfortable with:
Plants and animals inherit traits from their parents 3-LS3-1
Cells have parts, including a nucleus that holds genetic material MS-LS1-2
Structures help organisms survive, grow and reproduce 4-LS1-1
Show a recipe card for pancakes with one change written in red: "2 cups of salt" instead of "2 tablespoons of sugar". Then show a second card where "stir with a spoon" became "stir with a fork".
Warm-Up Prompt
"Each card has one change in its instructions. Which change would ruin the pancakes, and which would make no difference? Could a change in a recipe ever make the food better? Give an example."
Collect answers. Tell students that cells also follow written instructions, called genes, and that today they build a model of what happens when those instructions change. Keep the three kinds of answers (ruins it, no difference, better) on the board.
Direct Instruction15-20 minutes
Key words. A chromosome is a long, tightly coiled strand of DNA, the genetic material, found in the nucleus of a cell. Each chromosome holds many genes, and each gene is a section of the chromosome that carries the instructions for making one protein. Proteins are molecules that do most of the work in living things: they build structures such as hair and wings, they act as pumps and carriers, and some, called enzymes, speed up chemical reactions such as making pigment. A protein's shape decides what job it can do, the way a key's shape decides which lock it opens. A mutation is a change in the structure of a gene, that is, a change in its instructions. A trait is a feature of an organism, such as leaf color or wing size.
The model. A mutation may change the protein the gene codes for, or it may not. If the protein keeps the same shape and does the same job, the effect is neutral (no change in how the organism looks or works). If the new protein does its job better, or does a useful new job, the effect is beneficial. If the protein can no longer do its job, the effect is usually harmful. Whether a change helps or harms can depend on the environment, the place and conditions the organism lives in. Diagram 1 shows the model. This lesson does not cover how cells read genes to build proteins (beyond this standard).
Harmful effect: corn seedlings that cannot make chlorophyll
Corn plants have a gene for a protein that the plant needs to make chlorophyll, the green pigment that captures light energy for making food. In some corn plants this gene is changed, and the protein it codes for does not work. Seedlings that carry the changed gene from both parents grow white instead of green. Invented data: in a test planting of 120 seeds from one ear, 27 seedlings were white. All of them died within about two weeks, once the food stored in the seed was used up.
Result: Model: changed gene → protein that cannot do its job → no chlorophyll → leaves cannot make food → seedling dies. 27 ÷ 120 = 22.5% of the seedlings were white. The effect is harmful because it stops a function the plant cannot live without.
Beneficial effect: monarch caterpillars that eat a poisonous plant
Milkweed leaves contain a poison that blocks a protein found in the cell membranes of most animals. This protein acts like a pump, and animals need it to work. Monarch butterflies carry changes in the gene for this pump protein, so their pump has a slightly different shape that the poison cannot block well. Monarch caterpillars eat milkweed and store the poison, and many birds learn to avoid monarchs because they taste bad.
Result: Model: changed gene → pump protein with a shape the poison cannot block → caterpillar can eat milkweed and store its poison → more food and fewer bird attacks. The effect is beneficial: it changed both what the monarch can eat (function) and how safe it is from predators.
Neutral effect: a changed gene that leaves the protein's job unchanged
Invented data. Two lines of bean plants differ in one gene, the gene for a protein stored in the seed as food for the young plant. In line 2 the gene has a mutation, but the protein still folds into a shape that stores and releases food the same way. In a sprouting test, 19 of 20 line 1 seeds and 18 of 20 line 2 seeds sprouted, and after 3 weeks the seedlings were 14 cm and 15 cm tall on average.
Result: 19 ÷ 20 = 95% and 18 ÷ 20 = 90% sprouted, and the heights differ by 1 cm. Both differences are small enough to happen by chance between two groups of 20 seeds. Model: changed gene → protein that works the same → no change in the seed's structure or function → neutral effect.
Same mutation, different environments: wings on a windy island (Diagram 2)
Real pattern, invented numbers. On cold, windy islands, many kinds of insects have small wings or none. Imagine a beetle species in which a mutation in a gene for a wing-building protein stops the wings from growing. Scientists mark and release 200 winged and 200 wingless beetles on a windy island and 200 of each on a calm mainland, then search for marked beetles a month later. Island: 60 winged and 140 wingless found again. Mainland: 120 winged and 70 wingless found again.
Result: Island: 60 ÷ 200 = 30% winged and 140 ÷ 200 = 70% wingless. Mainland: 120 ÷ 200 = 60% winged and 70 ÷ 200 = 35% wingless. On the island, wind blows flying beetles out to sea, so the mutation is beneficial there. On the mainland, wings help beetles escape predators and reach food, so the same mutation is harmful.
After each example, have students trace the four links of the model aloud: gene, protein, structure or function, effect. Ask: "In which example did the protein still work? In which could the effect change if the organism moved to a new place?" Point out that the bean seeds in Example 3 are a fair test of a neutral effect only because both lines were grown the same way.
Guided Practice10-15 minutes
Pairs use the model with a real case and invented measurements. The Southern Ocean around Antarctica stays near -1.9 °C, colder than the freezing point of the blood of most fish. Over a long time, changes to genes in one group of Antarctic fish produced a new protein, an antifreeze protein, that sticks to tiny ice crystals in the blood and stops them from growing.
Guided practice data (invented, realistic values): temperature at which blood samples began to freeze
Fish
Antifreeze protein?
Blood freezes at
Antarctic fish, sample 1
yes
-2.2 °C
Antarctic fish, sample 2
yes
-2.3 °C
Related warm-water fish, sample 1
no
-0.8 °C
Related warm-water fish, sample 2
no
-0.7 °C
Draw the four-link model (gene, protein, structure or function, effect) for the Antarctic fish.
Use the table: would each fish's blood freeze in -1.9 °C water? Explain using the numbers.
By how many degrees does the antifreeze protein lower the freezing point? Use the average of the two samples in each group.
Is the antifreeze protein beneficial, harmful or neutral for a fish living at -1.9 °C? For a fish in 15 °C water? Making a protein uses energy and materials.
Write one sentence that explains why the same protein can have different effects in different places.
Independent Practice10-15 minutes
Each student develops a model for a new case. Some pea plants carry a mutation in a gene for a protein that helps build starch from sugar in the seed. The protein does not work, so these seeds keep more sugar and less starch. As the seeds dry, they lose more water and become wrinkled. Gardeners like these peas because they taste sweet.
Independent practice data (invented): pea seeds planted in two kinds of soil, 50 seeds per group
Seed type
Seeds that sprouted in cold, wet soil
Seeds that sprouted in warm soil
Round (working protein)
44
46
Wrinkled (protein does not work)
31
45
Students draw the model from gene to seed shape, find the four percents, and decide whether the mutation is harmful, beneficial or neutral for the pea plant in each kind of soil. They end with one sentence that explains why a trait gardeners like is not the same thing as a trait that helps the plant.
Closure5 minutes
Exit ticket: "Draw the four-link model for one example from today, and label the effect as harmful, beneficial or neutral. Then name one way the effect could change if the environment changed." Return to the recipe cards and ask which recipe change matches each effect in Diagram 1.
Differentiation Strategies
For Struggling Students
Give a four-box model template (gene → protein → structure or function → effect) to fill in for every case
Use the key-and-lock picture: a key with a changed tooth may still open the lock, open it better, or not open it
Provide a word bank: chromosome, gene, protein, shape, job, mutation, harmful, beneficial, neutral, environment
For Advanced Students
Ask students to find the weakest link in the bean seed evidence and design a larger test
Have students write a case where a mutation is beneficial and harmful at the same time, and weigh the two
Ask students to revise Diagram 1 so it also shows that the environment can change an effect
Assessment Guidance
What to Look For
Check that students trace every link of the model, from gene to protein to the structure or function of the organism, rather than jumping from "mutation" to "trait". Look for evidence-based labels: a harmful or beneficial effect needs data or a clear change in function. Listen for the misconceptions that all mutations are harmful, that a mutation always changes a trait, and that organisms change their genes because they need to.
02
Classroom Activities
3 Activities
1
Snap-Cube Proteins: Does It Still Fit?
25 minPairs
Pairs follow a gene card, a list of 8 building steps, to build a snap-cube "protein". The protein must fit a cardboard "job slot". Then they draw mutation cards, change one instruction at a time, rebuild and test the fit.
Procedure
Build the protein exactly as the gene card says (for example: step 1, 3 blue cubes in a row; step 2, add 2 red cubes going up from the right end; and so on to step 8). Check that it fits the job slot.
Draw a mutation card. Each card changes one step: a different color, a different direction or a different number of cubes. Rebuild the protein with the changed step.
Test the new protein in the job slot and record: fits the same, fits better (the teacher's second, "new environment" slot), or does not fit.
Repeat with 4 mutation cards, starting from the original gene card each time.
Sample Data (invented)
A class of 12 pairs tested 48 mutation cards in all. 20 changed only a cube's color and fit the same, 6 fit the new-environment slot better, and 22 did not fit.
Discussion Questions
Which kind of change on your cards left the shape the same? What effect on the organism does that match?
In the sample data, fewer than half of the changed proteins fit the same slot. What does the model suggest about how often a mutation helps?
Where does the model fall short? Name one way real proteins and genes are different from cubes and cards.
Modification for Distance Learning
Students use a drawing app or grid paper to build the shapes, and the teacher shares the job slot outline on screen.
2
Mutation Case Sort: Harmful, Beneficial or Neutral?
20 minGroups of 3-4
Groups sort 12 case cards about plants, animals and fictional organisms into harmful, beneficial and neutral, then pull out every card whose effect could change in a different environment. Each card names a gene, what happens to its protein and the organism's environment.
Sample Cards
A fictional tree frog has a changed gene for a skin protein that no longer keeps its skin moist, in a forest with a long dry season.
A fictional desert mouse has a changed gene for a kidney protein that saves more water.
A sunflower has a changed gene, but the protein it codes for has the same shape and job.
A fictional lizard has a changed gene for a toe-pad protein that grips smooth rock better, but it lives where the ground is all sand.
Discussion Questions
Which cards did your group disagree about? What evidence would settle the question?
The lizard card could move to a different pile. In what environment would its effect change, and why?
Why can a mutation be neutral even though the gene really did change?
Modification for Distance Learning
Use a drag-and-drop slide with three columns; groups type one reason under each card.
3
Model the Glowfin: A Fictional Fish
20 minPairs
The Glowfin is a fictional cave fish. Pairs get a map of one of its chromosomes with four labeled genes and develop a model for three mutations, then use the model to predict effects in two environments: a dark cave and a sunlit river.
Chromosome Map (fictional)
Gene G: glow protein that gives off light from the fins, used to find mates in the dark.
Gene P: pigment protein that colors the skin dark gray.
Gene F: fin protein that builds the fin rays.
Gene E: an enzyme that helps digest cave shrimp.
Task
Mutation 1 makes the glow protein brighter. Mutation 2 makes the pigment protein stop working, so the fish is pale pink. Mutation 3 changes gene E, but the enzyme keeps its shape. For each, draw the four-link model and label the effect in the cave and in the river. Invented observation to use: in the river, pale fish were caught by herons 3 times as often as gray fish.
Discussion Questions
Which mutation is neutral in both places? What tells you?
Mutation 1 helps in the cave. Could a brighter glow be harmful in the river? Explain with your model.
Revise your model: add one arrow or box that shows the environment's role.
Challenge Variation
Pairs invent a fourth gene for the Glowfin and a mutation in it whose effect is beneficial in the river but harmful in the cave, and explain it with the model.
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: A Model of How a Mutation Can Affect a Protein and the Organism
A gene is one section of a chromosome and holds the instructions for one protein. A change in those instructions (a mutation) may leave the protein the same (neutral effect), give it a shape that works better (beneficial) or give it a shape that cannot do its job (harmful). The model does not show how cells build proteins, which is beyond this standard.
Diagram 2: Winged and Wingless Beetles Found Again on an Island and a Mainland (Example 4)
Invented data from Example 4, drawn to scale. The wingless mutation goes with more beetles found again on the windy island and fewer on the calm mainland: the same change to a gene is beneficial in one environment and harmful in the other.
04
Homework Assignment
~30 min
MS-LS3-1 Homework: Mutations, Proteins and Effects
Directions: All data sets are invented for practice. Whenever you explain a mutation, use the four links of the model: gene, protein, structure or function, effect. Show your calculations.
Part 1: Using the Model (Problems 1-3)
Myotonic goats carry a mutation in a gene for a protein in the membranes of muscle cells. The changed protein does not let the muscles relax quickly, so when the goats are startled their legs stiffen for about 10-20 seconds and some fall over. They are not hurt and soon walk again. (a) Draw the four-link model for this mutation. (b) Is the effect harmful, beneficial or neutral for a goat on a fenced farm with no predators? (c) For a wild goat in a place with wolves? Explain each answer with your model.
Bar-headed geese fly over the Himalaya mountains, where the air has much less oxygen than at sea level. Changes in their genes for hemoglobin, the protein in red blood cells that picks up oxygen, give it a shape that grabs oxygen more easily. Invented data: in thin air like that at 6,000 m, a goose's blood loaded 85% of the oxygen it can carry, while blood from a related lowland goose loaded 60%. (a) How many percentage points more did the bar-headed goose load? (b) Use the model to explain how a change in a gene changed the bird's function. (c) Would you expect the same benefit for a goose that lives only at sea level? Explain.
Invented data: two groups of a moth species differ in the gene for an enzyme that digests leaves. In group 2, the gene has a mutation. Caterpillars were raised on the same leaves, 25 per group. Average mass gain in 10 days: group 1, 2.1 g; group 2, 2.0 g. Caterpillars that became moths: group 1, 23; group 2, 22. (a) Find the percent of each group that became moths. (b) Is the mutation's effect harmful, beneficial or neutral? Use both measurements. (c) What does your answer suggest about the enzyme's shape? (d) How could you make the evidence stronger?
Part 2: Data and Critique (Problems 4-6)
Develop a model for a fictional organism. The Snowpuff is a fictional bird of high mountains. One of its chromosomes holds genes for a feather-color protein, a beak-building protein and a protein that stores fat. A mutation in the fat-storage gene makes a protein that stores fat faster. (a) Draw the chromosome with the three genes, and the model chain for the mutation. (b) Predict the effect in a long, cold winter with little food. (c) Predict the effect in a warm place with plenty of food all year, where heavy birds fly more slowly from hawks. (d) What data would you collect to test each prediction?
Glimmer moths are fictional moths. A mutation in a gene for a wing-scale protein makes the wings shiny instead of brown. Invented data: in a dark forest, 120 brown moths and 120 shiny moths were released, and after one week 84 brown and 48 shiny moths were caught again. In a field of shiny wet grass, 120 of each were released, and 54 brown and 78 shiny were caught again. (a) Find the four percents. (b) Classify the effect of the mutation in each place, and explain using the model. (c) Explain why "harmful" and "beneficial" describe the mutation in an environment, not the mutation alone.
A student's poster says: "A mutation is when a chromosome turns into a different chromosome. Mutations always make an organism weaker, and an organism gets a mutation when it needs a new trait." (a) Find three errors in the poster. (b) Rewrite it as a correct model with the words gene, protein, shape, structure or function, and effect. (c) Give one example from this lesson for each of the three kinds of effect.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
Model
Every explanation traces gene → protein → structure or function → effect
Some links missing, for example jumping from mutation to trait
Effect and Evidence
Labels each effect correctly and backs it with data or a clear change in function
Labels are correct but unsupported, or one label is wrong
Environment
Explains how the environment can change whether an effect helps or harms
Mentions the environment without explaining it
Calculations
Correct percents and differences
Minor errors in one or two calculations
05
Quiz: 20 Questions
Interactive, with answers
Instructions
All data sets are invented, and all organisms are plants, animals or fictional species. Use the four links of the model (gene, protein, structure or function, effect) when you explain. Your score updates as you answer, and Reset quiz clears everything so you or your students can try again.
Multiple choice: pick an option to check it. Short answer: write your answer, then reveal the model answer.
0 of 20 answered · 0 correct
Question 1 of 20 · Multiple Choice
Where are genes located in a cell?
Answer: B
Genes are sections of the chromosomes, which are in the nucleus. Choice C mixes up the instructions with the product: a gene codes for a protein, but it is not inside the protein. Choice D is wrong because almost every cell of a plant or animal carries genes.
Question 2 of 20 · Multiple Choice
What does a gene carry?
Answer: A
A gene holds the instructions for one protein. Choice B confuses genes with stored food such as starch. Choice D is too large: a gene is only one section of one chromosome.
Question 3 of 20 · Multiple Choice
Which statement best describes a mutation?
Answer: B
A mutation is a change in a gene's structure, its instructions. Choice A says organisms change their genes on purpose, which they cannot do. Choice D describes one possible result of a mutation, not the mutation itself.
Question 4 of 20 · Multiple Choice
Why can a change in a protein's shape change what the protein can do?
Answer: A
Like a key and a lock, a protein works because its shape fits what it acts on. Choice B is wrong because different proteins do different jobs. Choice D is too strong: a new shape often works worse or the same.
Question 5 of 20 · Multiple Choice
A mutation changes a gene in a sunflower, but the protein the gene codes for has the same shape and does the same job. What is the effect on the plant?
Answer: C
If the protein works the same, the plant's structure and function are unchanged, so the effect is neutral. Choices A and B use "every", but mutations can have any of the three effects. Choice D is false: the genes of every organism can mutate.
Question 6 of 20 · Multiple Choice
Invented data: in a test planting of 60 seeds of a plant, 9 seedlings lacked a working pigment protein and died. What percent of the seedlings died?
Answer: B
9 ÷ 60 = 0.15, or 15%. Choice A uses the count as a percent. Choice C subtracts (60 - 9 = 51) and writes it as a percent. Choice D is the percent that survived.
Question 7 of 20 · Multiple Choice
Invented data: a fictional leaf beetle has a mutation in a gene for a digestive enzyme. The changed enzyme can break down the tough leaves of a shrub that other beetles in the area cannot digest. Why is this mutation likely to be beneficial?
Answer: A
The changed enzyme lets the beetle eat a food source that its competitors cannot, so it is more likely to find enough food. Choice B changes the shrub, not the beetle. Choice D confuses the food with the protein that digests it.
Question 8 of 20 · Multiple Choice
Invented data: in a fictional dark cave, 66 of 100 crickets with a mutation for longer antennae found food in a test, compared with 40 of 100 crickets with the usual antennae. What does this evidence suggest?
Answer: C
More crickets with long antennae found food (66% against 40%), so in this cave the mutation is beneficial. Choice A ignores the data and the environment. Choice B says the crickets changed on purpose; the mutation came first, and the dark cave favored it.
Question 9 of 20 · Multiple Choice
A student's model of the corn seedlings reads: "white leaves → changed gene → no chlorophyll → protein that does not work". What is wrong with it?
Answer: A
The model should run gene → protein → structure or function → effect: changed gene, protein that does not work, no chlorophyll, white leaves. Choice C is wrong because the missing protein is exactly why the leaves are white. Choice D reverses cause and effect.
Question 10 of 20 · Multiple Choice
Invented data: a mutation in a gene for a leaf-wax protein gives a desert plant waxier leaves. In a dry test, waxy plants lost 12 g of water a day and plants without the mutation lost 20 g. Which conclusion fits the model?
Answer: A
Waxy plants lost 8 g less water a day, 40% less, so the changed protein helps the plant keep water, which is beneficial in a desert. Choice B says the plant chose to change. Choice C judges by looks, not by function. Choice D breaks the gene-to-protein link of the model.
Question 11 of 20 · Multiple Choice
A rabbit has a mutation that makes its fur white all year. In which environment is this mutation most likely to be beneficial?
Answer: D
White fur blends in with snow, so predators find the rabbit less often where snow covers the ground most of the year. In choices A, B and C, white fur stands out against dark or brown ground, so it is likely harmful there.
Question 12 of 20 · Multiple Choice
Which is the best evidence that a mutation in a trout has a neutral effect?
Answer: D
A neutral effect means no change in structure or function, so the best evidence is a comparison in which both groups grow and survive alike. Choice B is a single fish, which could differ by chance. Choice A says nothing about the protein or the fish.
Question 13 of 20 · Multiple Choice
A tomato plant's gene for a stem-strengthening protein is changed, and the stems break in the wind. Which link of the model explains why the plant is harmed?
Answer: A
The changed gene gives a protein that does not strengthen the stem, so the structure fails. Choice C reverses the cause: the wind breaks the stem, but it did not cause the mutation. Choice D confuses a chromosome with a protein.
Question 14 of 20 · Multiple Choice
Invented data: 40 of 50 pea seeds with a working starch protein sprouted in cold, wet soil, and 28 of 50 seeds with a changed starch gene sprouted. How many percentage points lower was sprouting for the seeds with the changed gene?
Answer: C
40 ÷ 50 = 80% and 28 ÷ 50 = 56%, and 80 - 56 = 24 percentage points. Choice A subtracts the counts (40 - 28) without changing them to percents. Choice B is 100% - 80%, the working-protein seeds that did not sprout. Choice D divides 28 by 40 (70%) instead of turning each count into a percent of its own 50 seeds, then takes 100 - 70.
Question 15 of 20 · Short Answer
Explain, using the four links of the model, why a mutation may have no effect on an organism at all.
Gene: the instructions change. Protein: the new instructions still make a protein with the same shape, so it does the same job. Structure or function: nothing changes in how the organism is built or works. Effect: neutral. A full answer adds that this is why many mutations go unnoticed.
Question 16 of 20 · Short Answer
Invented data: in a pond with many fish that eat insects, 30 of 80 water beetles with a mutation for a darker shell were eaten in a month, and 50 of 80 beetles with the usual light shell were eaten. Find both percents and classify the effect of the mutation in this pond.
30 ÷ 80 = 37.5% of dark beetles and 50 ÷ 80 = 62.5% of light beetles were eaten. Fewer dark beetles were eaten, so in this pond the darker shell is beneficial. Model: changed gene → changed shell pigment protein → darker shell that fish see less easily → higher survival. A full answer notes that the effect could differ in another pond.
Question 17 of 20 · Short Answer
A classmate says, "All mutations are harmful." Use two examples from this lesson to argue against this claim.
Sample answer. The monarch's changed pump protein is beneficial: it lets caterpillars eat milkweed and store its poison. The bean seed protein in Example 3 is neutral: it works the same, and the seeds sprout and grow alike. Some mutations are harmful, like the corn seedlings that cannot make chlorophyll, but not all.
Question 18 of 20 · Short Answer
A mutation changes a gene for a protein in an owl's eye that detects dim light, so the owl sees better at night. Draw or describe the four-link model, and predict whether the effect would be the same for a bird that hunts only in bright daylight.
Gene for the light-detecting protein changes → protein with a shape that responds to dimmer light → eyes that work better at night → beneficial for an owl that hunts at night, because it finds more prey. For a daytime bird the change might be neutral, since the dim light ability is rarely used, or even harmful if very bright light is a problem. The environment decides.
Question 19 of 20 · Short Answer
Why do scientists say that a mutation "may" affect a protein and "may" affect the organism, instead of "always"?
Because many changes to a gene leave the protein's shape and job the same, and even a changed protein may not change how the organism works. When a protein does change, the effect on the organism can be harmful, beneficial or neutral, and it can depend on the environment. So the result is not fixed in advance.
Question 20 of 20 · Short Answer
Describe how you would use the snap-cube model to show a beneficial mutation. Then name one way the snap-cube model is different from a real gene and protein.
Sample answer. Start from the gene card, change one step on a mutation card, rebuild, and show that the new shape fits the "new environment" slot better than the original did. Limits: real genes are not lists of building steps on cards, real proteins are far smaller and fold on their own, and in real organisms the environment decides what "fits better" means.
0 of 20 answered · 0 correct
06
Frequently Asked Questions
10 Questions
What does MS-LS3-1 mean?
MS-LS3-1 asks students to build and use a model that shows why a change to a gene, called a mutation, may change a protein and may have harmful, beneficial or neutral effects on an organism. The code means Middle School, Life Science, core idea 3 (Heredity: Inheritance and Variation of Traits), performance expectation 1.
What grade is MS-LS3-1 taught in?
It is a middle school standard for grades 6-8. Schools usually teach it in grade 7 or 8 life science, in a genetics or heredity unit, next to MS-LS3-2 on asexual and sexual reproduction.
What is the assessment boundary for MS-LS3-1?
The official boundary says: "Assessment does not include specific changes at the molecular level, mechanisms for protein synthesis, or specific types of mutations." Students do not need to name kinds of mutations or explain how cells read genes. They need the idea that changed genes may lead to different proteins.
What is the difference between a chromosome, a gene and a protein?
A chromosome is a long, coiled strand of DNA in the nucleus. A gene is one section of a chromosome with instructions for one protein. A protein is the molecule built from those instructions, and its shape lets it do a job, such as building a wing or speeding up a reaction.
Are all mutations harmful?
No. Many mutations are neutral because the protein keeps its shape and job. Some are harmful because the protein stops working, and some are beneficial, like the change that lets monarch caterpillars eat poisonous milkweed. The same mutation can even help in one environment and harm in another.
What models work well for MS-LS3-1?
Physical models, such as snap-cube proteins built from instruction cards, and drawn flow models that link gene, protein, structure or function and effect. Students should use the model to predict, then compare it with data and name its limits.
Why does a protein's shape matter?
A protein works because its shape fits what it acts on, the way a key fits a lock. If a mutation changes the shape, the protein may do its job worse, better or not at all. If the shape stays the same, the job usually stays the same too.
Should students use human genetic diseases as examples?
This page uses plants, animals and fictional organisms only. That keeps the focus on the model and avoids putting any student's family or health on display. Teachers can still mention that mutations happen in all living things.
What misconceptions do students have about mutations?
Common ones are that every mutation is harmful, that a mutation always changes a trait you can see, and that organisms get mutations because they need them. The model and the environment cases on this page address each one.
How does MS-LS3-1 connect to natural selection?
Mutations are one source of the variation in traits that natural selection acts on. In MS-LS4-4 and MS-LS4-6 students explain how traits that are beneficial in an environment become more common over generations, and in high school HS-LS3-2 adds the sources of genetic variation.
07
Related Standards
6 standards
These standards connect to MS-LS3-1: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
3-LS3-1Prerequisite
Use data to show that traits are inherited and vary within a group
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