Mutations

Mutations

Middle School

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Learning Objectives

• Define a mutation and identify where it occurs in the genetic material.

• Describe different types of mutations, like substitution, insertion, and deletion.

• Explain the impacts of mutations, using harmful genetic disorders as examples.

• Differentiate between mutations that can be inherited and those that cannot.

Key Vocabulary

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Mutation

A mutation is a change in the genetic information or the DNA sequence of an organism.

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Gene

A gene is a small section of DNA that holds instructions for building a specific protein.

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DNA

DNA contains the genetic instructions for an organism's development, functioning, growth, and reproduction.

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Substitution

This mutation happens when one nucleotide base is swapped out for a different one in the DNA.

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Deletion

A deletion mutation occurs when a nucleotide base is removed from the DNA sequence, causing a frameshift.

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Insertion

An insertion mutation adds an extra nucleotide base into the DNA sequence, resulting in a frameshift.

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What Are Mutations?

• A mutation is a change in an organism’s genetic information, or DNA.

• ​DNA is found in chromosomes, and a gene is a specific section of DNA.

• Mutations happen when errors are made during the DNA copying process.

• Their effects can be harmful, beneficial, or have no noticeable impact.

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Multiple Choice

According to the slide, what is the primary cause of mutations?

• Errors that happen when DNA is copied

• Changes in an organism's diet

• An organism's choice to change its traits

• The process of a chromosome winding up

Types of Gene Mutations

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Substitution

• One nucleotide base is replaced by another in the DNA sequence.

• This type of mutation only changes a single base in the gene.

• It can sometimes change the protein that is made from the gene.

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Insertion

• An extra nucleotide base is added into the DNA sequence.

• This addition shifts the entire reading frame of the gene.

• It is known as a frameshift mutation, altering the resulting protein.

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Deletion

• A nucleotide base is removed from the DNA sequence.

• This removal also causes a significant frameshift mutation.

• The gene is read incorrectly, changing the protein that is produced.

Multiple Choice

What do insertion and deletion mutations have in common?

• They both cause a frameshift mutation

• They both replace one nucleotide with another

• They both remove an entire gene from the sequence

• They are both always beneficial to the organism

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Impact and Inheritance of Mutations

Germline Mutations

• These mutations happen in reproductive cells, which are the sperm and egg cells of an organism.

• They are inheritable, meaning they can be passed on from a parent to their offspring.

• Inherited mutations can sometimes cause genetic disorders like Sickle Cell Anemia and Cystic Fibrosis.

Somatic Mutations

• These mutations occur in the body cells of an organism, such as skin or muscle cells.

• Somatic mutations are not inheritable and only affect the individual organism in which they occur.

• Because they are not in reproductive cells, they are not passed on to an organism's offspring.

Multiple Choice

Under what condition can a genetic mutation be passed from a parent to their offspring?

• When the mutation occurs in the parent's sperm or egg cells

• When the mutation affects the parent's body cells, like skin or muscle

• When the mutation causes a visible change in the parent

• When the mutation is acquired later in the parent's life

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Common Misconceptions

Misconception	Correction
All mutations are harmful.	Most are neutral, and some can even be beneficial.
Mutations result in dramatic, superhero-like changes.	Mutations are microscopic DNA changes and don't cause large, visible changes.
All mutations are passed on to the next generation.	Only mutations in sex cells (sperm and egg) can be inherited.

Multiple Choice

How does a mutation in a body cell differ in its impact from a mutation in a sex cell?

• A mutation in a body cell affects only the individual, while a mutation in a sex cell can be passed to offspring.

• A mutation in a sex cell affects only the individual, while a mutation in a body cell can be passed to offspring.

• Mutations in body cells are always harmful, while mutations in sex cells are always neutral.

• Mutations in sex cells are temporary, while mutations in body cells are permanent.

Multiple Choice

Why are insertion and deletion mutations also known as frameshift mutations?

• Because they shift the way the rest of the gene's nucleotide sequence is read.

• Because they only occur at the beginning or end of a gene sequence.

• Because they cause the entire chromosome to change its shape.

• Because they replace a single nucleotide with a different one.

Multiple Choice

A single nucleotide deletion at the beginning of a gene sequence results in a non-functional protein. What is the most likely reason for this major change?

• The deletion caused a frameshift, altering the entire sequence of the protein.

• The single missing base was not important to the gene's function.

• The cell's repair mechanism immediately created a substitution mutation.

• The deletion only affects the first amino acid in the protein chain.

Multiple Choice

Knowing that Sickle Cell Anemia is an inherited disorder caused by a mutation, what can you conclude about the original mutation?

• It must have been present in a sperm or egg cell of a parent.

• It must have occurred in the body cells of the child after birth.

• It is a result of environmental factors, not genetics.

• It only affects the parents and is not passed to the child.

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Summary

• Mutations are changes in DNA that create genetic variation.

• The main types are substitution, insertion, and deletion.

• The effects of mutations can be harmful, beneficial, or neutral.

• Only mutations in reproductive cells can be passed on to offspring.

Poll

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

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• 3

• 4