Mutations are changes in DNA sequences that can occur due to errors in DNA replication or exposure to mutagens. There are several types of mutations including point mutations, which involve a single nucleotide change, and chromosomal mutations, which involve changes in larger chromosome structures. Point mutations can be further classified as transitions, transversions, frameshifts, insertions, and deletions. Chromosomal mutations include aneuploidy, which is an abnormal number of chromosomes, and polyploidy, which involves multiple sets of chromosomes. Mutations can be beneficial by creating genetic variation for evolution, but can also cause genetic disorders. Hugo de Vries originally coined the term mutation in the late 19th century and early studies helped uncover the mechanisms

1. MUTATION
Mrs. Praveen Garg
VITS College, Satna

2. INTRODUCTION
• A mutation is a change in a DNA sequence or nucleotide
sequence.
• A change occurs in a number or structure of a gene or a
chromosome is referred to as a genetic mutation.
• Mostly DNA as nucleic acid present in almost every
organism and made up of the long chain of nucleotides- a
polynucleotide chain.
• A mutation can also change gene expression. Change or
mutation in the structure or number of chromosomes also
results in genetic abnormalities.
• Mutations can result from DNA copying mistakes made
during cell division, exposure to ionizing radiation, exposure
to chemicals called mutagens, or infection by viruses.

3. • The mutation is an important biological process in nature.
• It can be helpful or harmful.
• The mutation creates variations in nature by providing new
alleles and hence helps in evolution.
• A sudden or undesirable mutation can cause cancer and
other harmful genetic disorders.
• Definition:
“Due to the replication errors, exposure to
mutagens and viral infections changes or alterations
occur in a DNA sequence which causes genetic
abnormalities, is known as mutation.”

4. HISTORY
• The “mutation” world was
originally derived from the Latin
word “mutare”. The meaning of this
is “to change.”
• The term “mutation” was coined
by Hugo De Vries in 1890.
• The mechanism of mutation was
studied by Morgan in 1910.
• In 1927, H. J. Muller performed
experiments of artificial
mutagenesis.
• He introduced mutation in
Drosophila and awarded the Nobel
Hugo De Vries

5. • On the basis of Types of cells:
 Somatic mutation
 Gametic mutation
• On the basis of Origin:
 Spontaneous Mutation
 Induced Mutation
• On the basis of Size and Quality of mutation:
 Gene mutations
 Chromosomal mutations
•
Kinds of Mutation

6.  On the basis of Types of cells:
 Somatic Mutation:
This type of mutation found in
somatic cells or non-reproductive cells of body, are known
as somatic mutation. They never inherit.
 Gametic Mutation:
This types of mutation found
in germ cell or reproductive cells, are known as gametic
mutation. They always inherit one generation to next
generation.

7.  On the basis of Origin:
 Spontaneous Mutation:
This type of mutation is
spontaneously produced in the organisms by the effect of
various factors of environment like radiation, temperature
and pressure.
 Induced Mutation:
This type of mutation are
artificially produced in the organisms by some chemicals,
X-ray and gamma rays. The factors inducing mutation are
called mutagen or mutagenic agents.

8.  On the basis of Size and Quality of mutation:
1. Gene or Point mutation:
• Mutation or series of mutations occur in the polynucleotide
sequence of a gene or single bas of DNA, that changes the
function of it, is referred to as gene mutations or point
mutation or base pair substitution.
• Point mutation are of two types:
 Substitution mutation- When one type of nucleotide base
is substituted by other type of nucleotide base, called as
substitution mutation.
 Frame shift mutation- It is a type of point mutation. Base
pair alteration causes abnormal reading frames which
ultimately results in an abnormal protein formation. With
one or two bases added or deleted, all of the three-base
codons change.

9. There are two types of Substitution mutations:
 Transition mutations
 Transversion mutations.
Transition mutations: It occur when a pyrimidine base
(i.e., thymine [T] or cytosine [C]) substitutes for another
pyrimidine base or when a purine base (i.e., adenine [A]
or guanine [G]) substitutes for another purine base.
Transversion mutations: It occur when a purine base
substitutes for a pyrimidine base, or vice versa; for example,
when a TA or CG pair replaces the wild type AT pair.

10. • Substitution– When some bases of a gene sequence are
replaced by other bases.
• There are three types of substitution mutations:
 Non-sense mutation
 Mis-sense mutation
 Silent mutation
POINT MUTATION

11. • A non-sense mutation occurs when one nucleotide is
substituted and this leads to the formation of a stop
codon instead of a codon that codes for an amino acid.
• A mis-sense mutation occurs when one nucleotide is
substituted and a different codon is formed; but this time,
the codon that forms is not a stop codon. Instead, the codon
produces a different amino acid in the sequence of amino
acids.
• In a silent mutation, a nucleotide is substituted but the
same amino acid is produced anyway. This can occur
because multiple codons can code for the same amino acid.

12. • Duplication– when some bases or a base duplicated in a gene
sequence.
• Inversion– When some gene sequences inverted and inserted
back into the original sequence.

13. FRAME SHIFT MUTATION
• A frame shift mutation occurs when an entire reading frame
is altered due to the single base substitution i.e, point
mutation.
• A reading frame is a sequence of all the codon between start
codon (AUG) to stop-codon.
• A point mutation (insertion or deletion) in the reading frame
changes the codon within it and thus the protein synthesis
altered, this type of point mutations are called frame shift
mutations.
• Frame shift mutations are apparent in severe genetic diseases
such as Tay–Sachs disease, Cancer, Sickle cell anemia. This
type of mutation is very harmful.
• Tay- Sachs disease is a fatal disease affecting the central

14. • Insertion– insertion or addition of a base into the gene
sequence. Often known as addition mutation 22.
• Deletion– When a base or some bases deleted from the gene
sequence.

15. 2. Chromosomal mutation or Aberration;
• Mutations that occur more than one gene are
called chromosomal mutations because they affect the
structure, function, and inheritance of whole DNA
molecules.
• These chromosome mutations result from one or more
breakage in the DNA molecules of the genome (from
exposure to radiation), and wrong rejoining.
Types of Chromosomal mutation according to change in
Number
 Aneuploidy- Loss or gain of one or more than one
chromosomes results in a condition called aneuploidy. Ex.-
Down syndrome.
 Polyploidy- It is another type of chromosome mutation is
the gain or loss of whole chromosome sets. That means,

16. o
translocation

17. A karyotypes of a human male with Down syndrome, showing a
full chromosome complement plus an extra chromosome 21.

18. ANEUPLOIDY
• Aneuploidy is the presence of an abnormal number of
chromosomes in a cell, for example a human cell having 45 or
47 chromosomes instead of the usual 46.
• It does not include a difference of one or more complete sets of
chromosomes. A cell with any number of complete
chromosome sets is called a euploid cell.
• It can be divided into following categories:
 Monosomy- There is a deficiency of one complete
chromosome (2n-1). These change are generally not found in
diploids.
 Nullisomy- There is a deficiency of one pair of one pair of
homologous chromosome (2n-2).
 Trisomy- There is an addition of one chromosome (2n+1). It
can occur in haploid set of chromosome.
 Tetrasomy- There is an addition of one set of chromosome

19. • Organisms are diploids (2n), they have two sets of
chromosome. When more than two sets of normal
chromosome are found in any organisms, then such organism
are known as polyploids and methods known to polyploidy.
• It can be divided into different types;
 Triploids: Organisms having three sets of chromosome (3n)
are known as triploids. This formation take place by the
fusion of diploid ovum with a haploid sperm.
 Tetraploids: Organisms have four sets of chromosomes (4n).
It take place by the union of diploid ovum and diploid sperm.
 Pentaploids: These have five sets of chromosome (5n).
 Hexaploids: These organism have six sets of chromosome
(6n).
 Decaploids: These organisms have ten sets of chromosomes
(10n).
POLYPLOIDY

20. Types of Chromosomal mutation according to change in
Structure:
• Changes in the structure of chromosome occur due to change in
the arrangement of genes lying on the chromosome.
• This process also known as Chromosomal aberration.
• It may be four types.

21.  Deletion: During
crossing over of
chromosome, few parts
of fragmented
chromosome do not
join at right position
and become deleted
and disappear on
cytoplasm.
 Thus chromosomal
mutation occur by the
deletion of nucleotides.

22.  Translocation: In
this, one or more
broken pieces of
chromosome joined
together at wrong
place which cause
changes in the
structure of
chromosomes.

23.  Inversion: There is
no change in no. of
genes. But ends of
one or more parts of
chromosomes during
union are changed
due to which only the
sequence of genes on
the chromosome is
changed.

24. • Duplication: One or
more part of
chromosome get united
with another
chromosome, due to
which there is
deficiency of genes in
one chromosome but
duplication of genes in
another chromosome.

25. • Most genomes contain mobile DNA elements that move
from one location to another. These are called transposoble
element.
• The movement of these elements can cause mutation, either
because the element arrives within a gene, or
recombination between pairs of mobile elements in different
locations.
Roles of Mutation:
• Mutation is very important for evolution, it provide heredity
variation.
• The variation produced by mutations, accumulated over a
long time period, and gives to the development of new
species.
• Mutation help in the survival of the species in changing
environment.
• Mutation help the organisms to adopt itself according to
environmental changes.

26. THANK YOU