Examining Spider Genes

Examining Spider Genes

Middle School

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Learning Objectives

• Define key genetic terms like genotype, phenotype, dominant, and recessive.

• Explain the relationship between genes, proteins, and the traits they express.

• Describe what gene mutations are and their potential effects on organisms.

• Analyze how both genetics and the environment can influence an organism's traits.

Key Vocabulary

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Gene

A gene is a part of DNA that has the instructions for building a specific protein.

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Trait

A trait is a specific characteristic of an organism, such as your eye color or height.

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Genotype

The genotype is the specific combination of alleles that an organism has for a certain trait.

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Phenotype

A phenotype describes the observable traits of an organism, such as its appearance or development.

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Dominant Allele

A dominant allele is one that masks the effect of a different allele in the phenotype.

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Recessive Allele

A recessive allele is a gene variation that is only expressed if two copies are present.

Key Vocabulary

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Protein

Complex molecules that do most of the work in cells for our traits.

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Mutation

A permanent alteration in the nucleotide sequence of an organism's DNA.

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Genetic Vocabulary: The Basics

• Genotype is the genetic 'recipe' for a trait, shown with letters.

• Phenotype is the physical trait you can actually see, like eye color.

• A dominant allele always shows its trait, even with just one copy.

• A recessive allele only shows its trait when two copies are present.

Multiple Choice

What is the primary role of an organism's genotype?

• It is the physical trait that you can see.

• It provides the genetic instructions for a trait.

• It is a version of a gene from one parent.

• It is a trait that only appears if two copies are present.

Multiple Choice

What is the main difference between a dominant and a recessive allele?

• A dominant allele is represented by a lowercase letter, and a recessive allele by an uppercase letter.

• A dominant allele is the physical trait you see, while a recessive allele is the genetic code.

• A dominant allele will always show its trait, while a recessive allele may not.

• A dominant allele requires two copies to show its trait, while a recessive allele needs only one.

Multiple Choice

If a person's genotype for eye color is 'Bb', with 'B' being the dominant allele for brown eyes and 'b' being the recessive allele for blue eyes, what will their phenotype be?

• Brown eyes, because the dominant allele for brown eyes will be expressed.

• Blue eyes, because the recessive allele is stronger when paired with a dominant one.

• A mix of blue and brown eyes, because both alleles are present in the genotype.

• Blue eyes, because you need two copies of the dominant allele for it to show.

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From Genes to Traits: The Recipe of You

• Our genes act like recipes in a giant cookbook called DNA.

• Each gene recipe gives instructions to build a specific protein.

• Proteins are the workers that build our observable traits.

• This creates the path: Gene -> Protein -> Trait.

Multiple Choice

What is the primary role of a gene?

• To provide the instructions for building a specific protein.

• To create the observable traits directly.

• To act as the workers that build our bodies.

• To store all of our traits in a large cookbook.

Multiple Choice

What is the relationship between a gene, a protein, and a trait?

• A gene provides instructions to build a protein, and the protein then builds a trait.

• A protein provides instructions to build a gene, which then builds a trait.

• A trait provides the instructions for a protein, which then builds a gene.

• A gene, a protein, and a trait are all the same thing.

Multiple Choice

If a gene's instructions are like a recipe, what would likely happen if the recipe has a mistake?

• The protein for that trait might be built incorrectly or not at all.

• All of the other genes in the DNA cookbook would be changed.

• The DNA cookbook itself would disappear.

• The observable trait would build a new, correct protein.

When the Code Changes: Gene Mutations

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Harmful Mutations

• ​A harmful mutation is a change in DNA that can hurt an organism.

• ​​These can cause genetic disorders, such as the disease cystic fibrosis.

• ​They may result in a protein that does not function correctly.

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Beneficial Mutations

• ​A beneficial mutation is a DNA change that helps an organism survive.

• ​​For example, it could help an insect resist harmful pesticide chemicals.

• ​This mutation gives the organism a survival advantage in its environment.

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Neutral Mutations

• ​A neutral mutation is a DNA change that has no noticeable effect.

• ​​The organism's physical traits are not affected by this type of change.

• ​Many mutations are neutral and do not cause any harm or benefit.

Multiple Choice

What is a gene mutation?

• A change in an organism's DNA

• A type of genetic disorder

• A protein that does not function correctly

• A chemical that helps an insect survive

Multiple Choice

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

• One helps an organism survive, while the other can hurt it.

• One creates new proteins, while the other destroys them.

• One affects physical traits, while the other does not.

• One is caused by chemicals, while the other is not.

Multiple Choice

A mutation in a rabbit's DNA causes it to have one white foot instead of brown, but this change does not impact its survival. How is this mutation best classified and why?

• As a neutral mutation, because it has no noticeable effect on the organism.

• As a harmful mutation, because it causes a physical change.

• As a beneficial mutation, because it gives the organism a new trait.

• As a genetic disorder, because it is a change in the organism's DNA.

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Nature and Nurture: Genes and the Environment

• An organism's traits are not decided by its genes alone.

• The environment plays a crucial role in how genes are expressed.

• A plant with tall genes may grow short without enough sunlight and water.

• Flamingos get their pink colour from the food they eat, not their genes.

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Multiple Choice

What determines the traits of an organism?

• Only the genes of the organism

• Only the environment the organism lives in

• Both an organism's genes and its environment

• The age of the organism

Multiple Choice

A plant has the genes to grow tall, but it is planted in a location with very little sunlight and water. What is the likely outcome?

• The plant will grow extra tall to reach for sunlight.

• The plant's genes will not be affected by the environment.

• The plant may grow short because its genes for tallness are not fully expressed.

• The plant will change its genes to better suit the environment.

Multiple Choice

Two flamingos have identical genes, but one is bright pink while the other is white. What is the best explanation for this difference in color?

• The white flamingo must have a genetic difference.

• The pink flamingo is older than the white flamingo.

• The pink flamingo's diet is different from the white flamingo's diet.

• The white flamingo must have spent more time in the sun.

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Common Misconceptions About Genetics

Misconception	Correction
Dominant traits are always the most common in a population.	Dominance means it masks a recessive allele; recessive traits can be common.
All genetic mutations are harmful.	Mutations can be helpful, neutral, or harmful, creating genetic diversity.
You can inherit traits your parents acquired, like large muscles.	Only traits passed through genes can be inherited, not acquired ones.
An organism's traits are determined only by its genes.	The environment also influences how genes are expressed, affecting traits.

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Summary

• Genotype is the genetic code, while phenotype is the observable trait.

• Dominant alleles mask the effects of recessive alleles.

• The journey from gene to trait is completed by the creation of proteins.

• Mutations change DNA, and an organism's traits are shaped by genes and environment.

Poll

On a scale of 1-4, how confident are you about explaining the difference between genotype and phenotype?

• 1 - Not confident at all

• 2 - A little confident

• 3 - Mostly confident

• 4 - Very confident