1.
MOLECULAR NATURE OF
MUTATION
PRESENTED BY PRANZLY

2.
MUTATION
A mutation is a change in the DNA’s nucleotide sequence.
An abrupt shift in the nucleotide sequence causes an organism’s
morphological traits to change. Such a change is referred to as a
mutation if it is heritable.
So, mutation is defined as any heritable change in the sequence of
nucleotide of DNA.
Organism with mutation is called MUTANT, while the organism
without mutation is WILD TYPE.
The term mutation was coined by Hugo de Vries in 1890

3.
FEATURE OF MUTATION
•Change in number- it is the change in the number or arrangement
of nucleotide sequence of a gene.
•It is heritable change in the DNA sequence.
•Permanent structural change inherited material DNA effects
•Can be harmful/beneficial or have no effects.
•Can be sometimes attributed to random chance events.
•Can be caused by mistakes during cell division or
•May be caused by exposure to DNA damaging agents to the
environment such as radiation and Mutagenic chemicals.

4.
TYPES OF MUTATION
POINT MUTATION
It happens as a result of a
nucleotide in a gene's specific
nucleotide sequence being replaced
(SUBSTITUTION) by another
nucleotide.
could involve the addition or deletion
of a base, a change to the base pair,
or both
FRAMESHIFT MUTATION
Addition or Deletion of nucleotide
causes shift of the reading frame of
mRNA
Insertion or deletion of a nucleotide
changes the entire frame.
So frame shift mutation bring greater
phenotypic change than point mutation.

5.
Based on transcriptional
property point mutation are
SILENT MUTATION
MISSENSE MUTATION
NON-SENSE MUTATION
TRANSITION:
It is the point mutation
occur by substitution of
one purine by another
purine or one pyrimidine
by another pyrimidine.
TRANSVERSION:
It is the point mutation
occur by substitution of
purine by pyrimidine and
vice versa

6.
SILENT MUTATION
 also known as neutral mutation
 This type of mutation results in codons that code for the
same amino acids as their original codon.
 Since the amino acid is identical to the original, the
structure and composition of the protein are unaffected.
 Phenotype remain same

7.
NON SENSE MUTATION:
• Mutation in which altered codon is stop codon or chain
terminating codon, such mutation is called non-sense mutation.
• Causes incomplete synthesis. Such incomplete protein is
always non-functional.
• Non-sense mutation bring greatest change in phenotype of an
organism.

8.
MIS-SENSE MUTATION
•The altered codon in this mutation codes for a different amino acid
(other than original).
•The protein produced from the new amino acid that the mutation
codon codes for is changed.
•Such proteins may have reduced activity or no activity at all.
• If altered amino acids lie on active site of protein then such protein
become completely non-functional.
• causes phenotypic change in organism

9.
FRAMESHIFT MUTATION

10.
SUBSTITUTION is an exchange between two bases
( change in a single chemical letter such as substituting AT to AC)
Example of substitution mutation is caused by substitution mutation
where in sickle cell anemia
(GAG mutates to GTG and lead to Glutamine -Valine) change
which leads to the production of sickle shaped RBCs.
Point mutation –involves change in single base pair of DNA

11.
MUTAGENS
Any physical, chemical or
biological substance that
can change the genetic
makeup of the organism
thereby causing mutation.
PHYSICAL MUTAGENS
Ultraviolet (UV) light is a
physical mutagen whose
energy causes adjacent
thymine (or cytosine)
bases in the DNA to
covalently link together
forming dimers
Ionizing radiations, such as
gamma rays and X-rays,
can cause physical breaks
in the double-strand DNA
CHEMICAL MUTAGENS
Nitrous acid is an
example of a chemical
mutagen that converts
DNA’s adenine bases to
hypoxanthine bases
Elements like Arsenic,
Nickel, Chromium
Organic compounds like
benzene
BIOLOGICAL
MUTAGENS
Transposons , viruses
Bacteria like helicobacter
pylori can increase risk of
stomach cancer