Exploring Variation in Spider Silk

Exploring Variation in Spider Silk

Middle School

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Learning Objectives

• Distinguish between inherited and acquired traits.

• Describe the relationship between genes, proteins, and traits.

• Compare sexual and asexual reproduction and their effects on genetic variation.

• Explain how mutations can lead to changes in traits.

Key Vocabulary

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Trait

A specific characteristic of an organism, like its eye color, hair texture, or overall height.

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Gene

A segment of DNA on a chromosome that contains the instructions for making a specific protein.

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Inherit

To receive genetic information and traits from parents through the process of sexual reproduction.

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Protein Molecule

A large, complex molecule that carries out a specific job in the body to create traits.

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Variation

The natural differences in traits among individuals that belong to the same species.

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Mutation

A random change in a gene's DNA sequence that can alter the protein it creates.

Key Vocabulary

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Sexual Reproduction

A type of reproduction involving two parents, resulting in genetically unique offspring that are not identical.

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Chromosome

A thread-like structure in a cell's nucleus that contains the genetic information, known as DNA.

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Allele

An allele is one specific form of a gene that is inherited from each parent.

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Homozygous

This means having two identical alleles for a specific gene, one from each of the parents.

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Heterozygous

This means having two different alleles for a specific gene, one from each of the parents.

Inherited vs. Acquired Traits

• Inherited traits are passed down from parents through genes.

• Acquired traits are developed by an organism during its lifetime.

• Only inherited traits can be passed on to the next generation.

Multiple Choice

Which statement best defines an inherited trait?

• A characteristic passed from parents to offspring through genes

• A skill that an organism learns by practicing

• A feature that an organism gets from its environment

• A temporary change in an organism's behavior

Multiple Choice

How is an acquired trait different from an inherited trait?

• An acquired trait is developed during a lifetime, while an inherited trait is passed down from parents.

• An acquired trait is only found in animals, while an inherited trait is found in all organisms.

• An acquired trait is passed to offspring, while an inherited trait is not.

• An acquired trait relates to physical appearance, while an inherited trait relates to behavior.

Multiple Choice

A dog's owner teaches it how to fetch a ball. If this dog has puppies, what is the most likely outcome?

• The puppies will not be born knowing how to fetch because it is an acquired trait.

• The puppies will be born knowing how to fetch because it is an inherited trait.

• There is a 50% chance the puppies will be born knowing how to fetch.

• Only the male puppies will be born knowing how to fetch.

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How Genes Create Traits

• Your body's cells have a nucleus with chromosomes that hold your genes.

• Genes are instructions for building specific protein molecules inside the cell.

• A protein’s unique shape, or structure, determines its job, or function.

• The function of these proteins creates your observable traits, like eye color.

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Multiple Choice

What is the primary function of a gene?

• To act as instructions for building specific proteins.

• To create energy for the cell's nucleus.

• To hold the chromosomes together inside the nucleus.

• To directly form an organism's observable traits.

Multiple Choice

What is the relationship between a protein's structure and an organism's traits?

• A protein's specific structure determines its function, which creates a trait.

• A protein's function is to copy the gene's instructions for storage.

• A protein's structure is determined by the trait an organism has.

• A protein's function is to combine with chromosomes to form new genes.

Multiple Choice

If a gene's instructions were changed, causing a protein to be built with a different shape, what would be the most likely outcome?

• The protein's function would change, leading to a different trait.

• The protein would attach to a different chromosome in the nucleus.

• The nucleus would create a new gene to fix the mistake.

• The cell would use a different protein that has the correct shape.

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Asexual vs. Sexual Reproduction

Asexual Reproduction

• This type of reproduction involves only one parent passing on its genes.

• The offspring are genetically identical to the parent, much like a clone.

• A bacterium splitting into two identical cells is an example of this.

Sexual Reproduction

• This form of reproduction requires genetic material from two different parents.

• Each parent contributes half of the genetic information to create the offspring.

• The offspring has a unique combination of traits from both of its parents.

Multiple Choice

What is the primary difference between asexual and sexual reproduction?

• The number of parents involved in the process.

• The speed at which the offspring are created.

• The environment where the parents live.

• The size of the offspring that are produced.

Multiple Choice

How does the genetic makeup of offspring differ between asexual and sexual reproduction?

• Asexual reproduction results in identical offspring, while sexual reproduction results in unique offspring.

• Asexual reproduction requires genetic material, while sexual reproduction does not.

• Asexual reproduction creates a clone, while sexual reproduction creates a copy.

• Asexual reproduction involves genes from two parents, while sexual reproduction involves genes from one.

Multiple Choice

A single bacterium divides and produces two new cells. What can you conclude about this process and its offspring?

• It is a form of asexual reproduction because the offspring is genetically identical to the single parent.

• It is a form of sexual reproduction because it involves genetic material from two different bacteria.

• It is a form of asexual reproduction because bacteria are very simple organisms.

• It is a form of sexual reproduction because it results in two cells instead of one.

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Genetic Variation and Alleles

• Genetic variation is the diversity of traits that helps species adapt.

• You get different gene versions, called alleles, from each of your parents.

• If you inherit two identical alleles, you are homozygous for that trait.

• If you inherit two different alleles, you are heterozygous for that trait.

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Multiple Choice

What is the primary role of genetic variation within a species?

• It helps the species adapt to its environment.

• It makes all members of a species look identical.

• It prevents parents from passing genes to their offspring.

• It ensures that traits within a species never change.

Multiple Choice

What does it mean if an individual is described as heterozygous for a trait?

• The individual has inherited two different alleles for the trait.

• The individual has inherited two identical alleles for the trait.

• The individual has not inherited any alleles for the trait.

• The individual has only one version of the gene for the trait.

Multiple Choice

If an organism is homozygous for a specific trait, what can be concluded about the alleles it inherited?

• The alleles it received from both parents for that trait are identical.

• The alleles it received from both parents for that trait are different.

• The organism is able to create its own unique alleles.

• Only one parent provided an allele for that trait.

Mutations: The Source of New Traits

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Harmful Mutations

• A mutation is a permanent and random change in a gene's sequence.

• This can change a protein's structure and function in a negative way.

• A harmful mutation can cause problems for an organism, like a disease.

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Beneficial Mutations

• Sometimes, a mutation can give an organism a surprising survival advantage.

• It can change a protein's function in a way that is helpful.

• Better camouflage helps a moth avoid being eaten by hungry predators.

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Neutral Mutations

• Many mutations do not have any noticeable effect on an organism's traits.

• The change in the protein does not cause any harm or benefit.

• It does not affect the organism's ability to survive and have offspring.

Multiple Choice

What is a mutation?

• A temporary change in an organism's behavior

• A permanent and random change in a gene's sequence

• A health problem caused by the environment

• A predictable change that helps an organism grow

Multiple Choice

What is the primary difference between a beneficial mutation and a harmful mutation?

• One type changes a gene's sequence while the other changes a protein's structure.

• One type is always permanent while the other is temporary.

• One type provides a survival advantage while the other causes problems.

• One type affects an organism's traits while the other has no effect.

Multiple Choice

A cat is born with a mutation that gives it a small white spot on its fur, but this spot does not help it hide or affect its health. Which of these best explains what kind of mutation this is?

• A harmful mutation, because any change to a protein is negative.

• A beneficial mutation, because the new trait is an advantage.

• A neutral mutation, because it does not affect the organism's ability to survive.

• A temporary mutation, because it did not cause a disease.

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Common Misconceptions

Misconception	Correction
All traits are inherited.	Learned skills are acquired, not inherited through genes.
Offspring are an even blend of their parents' traits.	Offspring inherit a random mix of genes, not a perfect blend.
All mutations are harmful.	Mutations can be harmful, neutral, or even helpful to a species.

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Summary

• Traits can be inherited from genes or acquired through life experiences.

• Genes contain the instructions for proteins that determine our traits.

• Asexual reproduction creates identical offspring, while sexual reproduction creates unique offspring.

• Mutations are random changes in genes that can create new traits.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1 - Not confident at all

• 2 - A little confident

• 3 - Mostly confident

• 4 - Very confident