Insertion Mutation: Diseases & Examples

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  • 0:01 What Are Mutations?
  • 0:26 What Are Insertion Mutations?
  • 2:29 Diseases Caused by…
  • 3:47 Lesson Summary
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Lesson Transcript
Angela Lynn Swafford

Lynn has a BS and MS in biology and has taught many college biology courses.

Expert Contributor
Amanda Robb

Amanda holds a Masters in Science from Tufts Medical School in Cellular and Molecular Physiology. She has taught high school Biology and Physics for 8 years.

Insertion mutations occur when extra genetic material is added to a DNA sequence. Learn about insertion mutations and some of the diseases they can cause in this lesson.

What Are Mutations?

Any permanent change in a DNA sequence is called a mutation. DNA is found in all organisms and is the unit of heredity. This means that mutations can sometimes be passed on to offspring. Mutations can be beneficial, neutral (have no effect), or detrimental. While there are many different kinds of mutations, we will focus on just one type called an insertion mutation.

What Are Insertion Mutations?

Insertion mutations occur when extra nucleotides are put into a DNA sequence, making it longer than it should be. So, what are nucleotides? They are the repeating units of a DNA sequence. There are four nucleotides, and each has a different nitrogenous base:

  1. Thymine (T)
  2. Adenine (A)
  3. Guanine (G)
  4. Cytosine (C)

We write DNA sequences using strings of these four bases. Let's say a DNA sequence reads CAGC. If a T was accidentally inserted between the G and C when this sequence was being copied, it would now read CAGTC. An insertion mutation has occurred. If this mutation was in a gene, or the part of a DNA sequence that codes for a protein, it could be detrimental and result in the production of a nonfunctional protein.

Insertion mutations can be small, like in the CAGTC example in which only one nucleotide was inserted, or they can be large, with many nucleotides being added. If the number of bases inserted is not a multiple of three, then the insertion mutation is also considered a frameshift mutation. Frameshift mutations change all of the codons following the location of the DNA change, in this case an insertion. A codon is a 3-base sequence that codes for one amino acid. Amino acids are the building blocks of proteins, and changes in the sequence of amino acids can result in proteins that don't work properly.

Two examples of insertion mutations; one is a frameshift mutation, the other is not.
Insertion Mutation Examples

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Additional Activities

A Day in the Life

In this writing activity, students will research what it is like to live with a disease caused by an insertional mutation. Students will choose an insertional mutation from the lesson or from their own research and learn about what the symptoms and challenges are that patients face. Then, they will write a short story of 2,000 words that describes what life is like with the condition.

For example, a student might choose to write a story about someone with cystic fibrosis. They would use academic websites like Mayo Clinic or NHS to learn about the symptoms of cystic fibrosis. They could also use support websites, such as the American Lung Foundation, to learn what life is like with cystic fibrosis. They can develop a character and write a story about living with the disorder. For example, they might write what it feels like in day to day life, what it is like interacting with doctors or managing relationships with the disease.

Student Instructions

Now that you're familiar with the science behind insertional mutations, it's time to dig deeper into the diseases that insertional mutations can cause. In this writing activity, you'll be writing a short story about what it's like to live with one of the insertional mutations explained in the reading. For example, you might write a paper about a person with cystic fibrosis or Huntington's disease. To make sure your story meets all the requirements, check out the criteria for success below.

Criteria For Success

  • Short story is at least 2,000 words
  • Story focuses on an individual with a disease caused by an insertional mutation
  • Story includes details about the science behind the mutation, as well as scientifically accurate information about the patient's symptoms, treatment and prognosis
  • Story includes details about the person's life living with the disease

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