2. DEFINE OF INSERTION
• An insertion, as related to genomics, is a type of mutation that
involves the addition of one or more nucleotides into a segment of
DNA. Insertion can involve the addition of any
• number of nucleotides, from a single nucleotide to an entire piece
of a chromosome
• • Insertion alters the genetic code and lead to change in resulting
protein or gene function.
3. CAUSE
➤ When the replicating strand “slips,” or wrinkles, which allows the extra nucleotide
to be incorporated.
➤ DNA repair mechanism (during repair of certain DNA lesions nucleotide may b
inserted to DNA sequence leading to insertion mutation)
➤ Transposable elements (jumping Genes when transposons inert themselves on
new location on genome they cause insertion).
➤ Exposure to certain mutagens.
4. OCCURRENCE
• How insertion occurs?
In DNA insertion mutation occurs When one or more nucleotides are added to
DNA sequence. This can happen during replication process of some other external
factors such as exposure to chemicals.
During replication process the DNA strands separate and each serve as template for
synthesis of new strand some times DNA polymerase may slip or stutter leading to
temporary dissociation or re- association of the template and newly synthesized
strand this can result to addition of extra nucleotide when the polymerase resume
synthesis
5. • Continue
Leading to insertion. Inserted nucleotide can be of any types such as
(A,T,C and G)that can occur on any location on DNA sequence.
Inserted nucleotide alters the genetic code for specific amino acids
that consequently alters the structure of resulting protein.
6. • Chromosomal insertion occurs when a segment of one chromosome is translocated
and inserted into an interstitial region of another non-homologous chromosome
(interchromosomal insertion), or into a different region of the same chromosome
(intrachromosomal insertion).
• For example;
• Fragile x syndrome is genetic mutation that is caused by insertion. It is caused by a
change to a gene on the X- chromosome called the FMR1 gene. This gene produces a
• protein that helps the brain to function normally. If this gene is changed or altered in
any way, it cannot produce its normal protein.
7. TYPES OF INSERTION
• There are 3 main types of insertion
1. Single nucleotide insertion
2. Short repeat insertion
3. Transposon insertion
8. SINGLE NUCLEOTIDE INSERTION
• In this type of insertion, a single extra nucleotide is inserted into the
DNA sequence. It can occur in various locations within the genome
and may result from DNA replication errors or repair processes.
• Single nucleotide insertions can cause frame shift mutations if they
disrupt the reading frame, leading to significant changes in the
resulting protein sequence.
9. 2.SHORT REAT INSERTION RA
• Short repeat insertions involve the insertion of a small sequence of repetitive
DNA elements into the DNA sequence. These repetitive sequences, also known as
microsatellites or short tandem repeats (STRs), can vary in length from a few
nucleotides to several dozen nucleotides.
•
• Short repeat insertions can occur due to slippage during DNA replication or
repair and are associated with certain genetic disorders and diseases
10. 3.TRANSPOSONS INSERTION
• Transposons insertion occurs due to the jumping Genes or
transposable elements.when these elements insert themselves on
new location in genome they cause the transposon insertion.
• This can disrupt Genes or regulatory sequence leading to genetic
mutation.
11. EFFECTS OF INSERTION
Some may cause no effect at all, whereas others, even single nucleotide insertions, can
completely disrupt the function of a gene and lead to a pathogenic variant associated
with a genetic disease.
Some genetic diseases that are caused by insertion are given below
i. Fragile X Syndrome.
Ii. Huntington’s Disease.
Iii. Myotonic dystrophy.
Iv. Cystic fibrosis.
12. ➤ Insertion mutations can change the shape of the protein made,
create a non-functional protein, or stop the protein from being made
entirely.
➤ Can effect the binding of transcription factor or other regulatory
molecules leading to abnormal gene expression pattern.
➤ If the inserted nucleotide cause a shift in leading frame of the DNA
sequence.it leads to frame shift mutation that often results in non
functional protein.
