Frameshift mutation is a type of genetic mutation that occurs when the addition or deletion of one or more bases in a DNA sequence, which causes a reading shift of the codon and results in a drastic change in the sequence of the encoded amino acids.
Normally, DNA bases are read in codon triplets, and each codon codes for one amino acid. However, when bases are added or removed in a DNA sequence, this disrupts the reading frame change, so that the codon sequence after the change will be shifted. As a result, the codon read after a frameshift mutation will be different from the previous codons, and usually produces a different amino acid sequence.
The following are the steps in explaining frameshift mutations:
What’s that
Frameshift mutation is a type of genetic mutation that occurs when one or more bases are added or removed in a DNA sequence, which results in a shift in the codon reading frame during protein synthesis.
DNA Structure:
DNA consists of two strands linked together to form a double helix. Each DNA strand consists of the base sequences adenine (A), thymine (T), guanine (G), and cytosine (C).
Codon:
A sequence of three bases in DNA is called a codon. Each codon represents one particular amino acid in the protein to be synthesized.
Addition or deletion of bases:
Frameshift mutations occur when one or more bases are added or deleted from a DNA sequence. This changes the reading of the next codon and shifts all codons that follow it.
Reading shift:
Because of this shift, the sequence of encoded codons will be different. For example, if there is a deletion of one base, all codons after the deletion point will change. This results in major changes in the sequence of the resulting amino acids.
Impact on protein:
Frameshift mutations can have a very significant impact on protein synthesis, because changes in the reading frame cause drastic changes in the amino acids produced. These mutations can disrupt the structure and function of proteins, potentially causing genetic disorders or diseases.
Changes in the amino acid sequence produced by frameshift mutations can disrupt the structure and function of the protein formed. Because encoded amino acids depend on precise codon reading, changes in the amino acid sequence can result in a non-functional protein or even none at all.
Some diseases known to be caused by frameshift mutations include HNPCC (Hereditary Nonpolyposis Colorectal Cancer) syndrome and Duchenne muscular dystrophy.
Frameshift mutations can occur spontaneously or be caused by factors such as radiation or chemicals. These mutations can have serious consequences in human health, because they can cause certain genetic disorders or genetic diseases.
Frequently Asked Questions about Frameshift Mutation
1. What is a frameshift mutation?
A frameshift mutation is a type of genetic mutation that occurs when the addition or deletion of nucleotides in DNA disrupts the normal reading frame during protein synthesis. This disruption shifts the entire “reading frame” of the genetic code and can lead to significant changes in the resulting protein structure and function.
2. How does a frameshift mutation occur?
Frameshift mutations can occur through two main mechanisms:
– Insertion: This happens when one or more nucleotides are inserted into the DNA sequence, causing a shift in the reading frame.
– Deletion: This occurs when one or more nucleotides are deleted from the DNA sequence, also causing a shift in the reading frame.
3. What are the effects of frameshift mutations?
Frameshift mutations can have profound effects on the resulting protein. Since they disrupt the reading frame, the entire sequence of amino acids may be altered from the point of mutation. This can lead to the production of a non-functional protein or a protein with a completely different structure and function. Frameshift mutations are often deleterious and can cause genetic disorders or diseases.
4. Can frameshift mutations be inherited?
Yes, frameshift mutations can be inherited. If a frameshift mutation occurs in the DNA of germ cells (sperm or egg cells), it can be passed on to offspring. Inherited frameshift mutations can lead to genetic disorders or an increased risk of certain diseases in future generations.
5. What are some examples of genetic disorders caused by frameshift mutations?
Some examples of genetic disorders caused by frameshift mutations include:
– Duchenne muscular dystrophy: This is a severe form of muscular dystrophy caused by frameshift mutations in the dystrophin gene.
– Tay-Sachs disease: It is a neurodegenerative disorder caused by frameshift mutations in the HEXA gene.
– Cystic fibrosis: This is a genetic disorder caused by frameshift mutations in the CFTR gene.
6. Can frameshift mutations occur in non-coding regions of DNA?
Yes, frameshift mutations can occur in non-coding regions of DNA as well. While non-coding regions do not encode proteins, they play important roles in gene regulation and other cellular processes. Frameshift mutations in non-coding regions can disrupt these processes and have significant effects on gene expression and cellular function.
7. Are frameshift mutations reversible?
Frameshift mutations are generally considered irreversible. Once the reading frame is shifted, subsequent codons and amino acids will be altered. However, in rare cases, certain compensatory mutations or genetic mechanisms may restore the reading frame and partially mitigate the effects of the frameshift mutation.
8. How are frameshift mutations detected?
Frameshift mutations can be detected through various genetic testing methods, such as DNA sequencing or targeted mutation analysis. These techniques involve analyzing the DNA sequence for insertions or deletions of nucleotides that disrupt the reading frame. Genetic testing can be performed on blood samples, tissue samples, or other biological samples, depending on the specific mutation being investigated.
9. Can frameshift mutations be corrected or treated?
Currently, there are limited direct methods to correct frameshift mutations. However, researchers are exploring potential therapeutic approaches, such as gene editing technologies like CRISPR-Cas9, to correct or mitigate the effects of frameshift mutations. Additionally, some genetic disorders caused by frameshift mutations may be managed or treated symptomatically to improve quality of life.