This document discusses different types of mutations including: - Gene mutations such as point mutations (missense, nonsense, silent) and frameshift mutations (insertions, deletions). - Chromosomal mutations including numerical abnormalities (polyploidy, aneuploidy) and structural abnormalities (balanced like translocations/inversions, unbalanced like duplications/deletions). - Mutations can also be classified by the type of cell involved (somatic, germinal), mode of origin (spontaneous, induced), direction of mutation (forward, reverse), and phenotypic effects (morphological, lethal, conditional, biochemical).

1. Mutations
Ph student :Amel Mahrooz Abdullah
ÇANKIRI KARATEKİN ÜNİVERSİTESİ
FEN BİLİMLERİ ENSTİTÜSÜ

2. Mutation
 Is a process that
produces a gene or
chromosome that
differs from the wild
type.
 The mutation may
result due to changes
either on the gene or
the chromosome itself.

3. History
 The earliest record of
point mutation dates back
to 1791, when Seth
Wright noticed a lamb with
exceptionally short legs in
his flock of sheep.
 The first scientific study of
mutation started in 1910,
when Morgan started his
work on fruit fly
Drosophila melanogaster
after he observed white
eyed male individuals
among red eyed male
individuals.

4.  Mutations can be bad,
leading to cancer,
aging, birth defects, self
aborted embryos
 Be good, making an
organism survive better
in its environment
Example: bacteria
becoming antibiotic
resistant

5. Mutagens
 The substances or agents which induce mutations.
They may be physical, chemical or biological.
1.Physical i.Ionizing : Radiations- Xrays, gamma,
Alpha,Beeta, protons, nutrons etc ..
ii. Non Ionizig : Temperature
2.Chemical : Elements such as arsenic, nickel and
chromium. Some organic compounds like benzene are
also considered to be mutagenic in nature.

6.  3.Biological Mutagens: They may be viral or
 bacterial.
 H. Pylori- implicated in stomach cancer
 Hepatitis B virus- implicated in liver cancer
 H. papiloma virus-implicated in cervical cancer
 Human T-cell lymphocytic virus implicated in
lymphoma

7. Types of Mutation
Mutations can be grouped according to
 Their size
 The Type of Cell Involved
 Mode of Origin
 Direction of Mutation
 Phenotypic Effects

8. Mutations by their size
 Submicroscopic (micro mutations, gene
mutations a single base.
 Microscopic macro mutations , chromosomal
abnormalities.

9. Gene Mutations
 Change in the nucleotide sequence of a gene may only
involve a single nucleotide
Types of Gene Mutations
 Point Mutations
a) Missense
b) Nonsense
c) Silent
 Frameshift
a) Insertions
b) Deletions

10. Point Mutations
 Point Mutations or substitution is a genetic mutation
where a single nucleotide base is changed

11. a. Missense Mutation
This type of mutation is a change in one DNA base
pair that results in the substitution of one amino acid
for another in the protein made by a gene. Example is
Sickle cell anemia

12. b. Nonsense Mutation
 Is also a change in one DNA base pair. Instead of
substituting one amino acid for another, however, the
altered DNA sequence prematurely signals the cell to
stop building a protein. This type of mutation results in a
shortened protein that may function improperly or not at
all. Examples include duchenne muscular dystrophyand
thalassemia

13. c. Silent Mutations
 Are mutations in DNA that do not have an
observable effect on the organism's phenotype.
 For example ,if the codon AAA is altered to
become AAG, the same amino acid –lysine–will
be in corporated into the peptide chain

14. Frame Shift Mutations
1. Insertion Mutations : An insertion changes the
number of DNA bases in a gene by adding a piece of DNA.
As a result, the protein made by the gene may not function
properly. Examples Cystic fibrosis.
 Example
UUU UUA UCU Phe-Leu-Ser
UUU UUA UUU UCU Phe-Leu-Phe-Ser

15. 2. Deletion
A deletion changes the number of DNA bases by removing
a piece of DNA. Small deletions may remove one or a few
base pairs within a gene, while larger deletions can remove
an entire gene or several neighboring genes.
Example
UUU UUA UUU UCUPhe-Leu-Phe-Ser
UUU UUA UCUPhe-Leu-Ser

16. Chromosomal mutation
Types of chromosomal abnormalities
 Numerical abnormalities : polyploidy : triploidy , tetraploidy
aneuploidy : trisomy , monosomy
 Structural abnormalities
1 .Balanced : if there is no gain or loss of chromosomal
material
• Translocations
• Inversions
2. Unbalanced if there is gain or loss of chromosomal
material
• Duplication
• Deletion
• Insertion
• Ring chromosome
 Polyploidy:occurs when there are more than two paired
(homologous) sets of chromosomes(triploidy, tetraploidy,
etc.).

17. Balanced Structural chromosomal
abnormalities
 Translocations
Movement of a gene
may take place to a
non-homologous
chromosome and this
is known as
translocation

18.  Inversion
The movement of a
gene within the same
chromosome is
called inversion.

19. Unbalanced Structural chromosomal
abnormalities
 Duplication occurs
when a segment of the
chromosome is
repeated, once or
several times.
 Deletion -loss of a
segment of the
chromosome

20. Unbalanced Structural chromosomal
abnormalities
 Ring chromosome
Two ends of the
segment between
break points are
joined to form a
circular structure.

21.  Mutations can be grouped according to
 Their size
 The Type of Cell Involved
 Mode of Origin
 Direction of Mutation
 Phenotypic Effects

22. 1. Somatic mutations
 Mutations that are in the somatic tissues of the body.
 Mutations are not transmitted to progeny
 caused by environmental factors, such as exposure to
ultraviolet radiation
2. Germinal mutations
 Mutations that are in the germ tissues of the body.
 Mutations may be transmitted to progeny
 can be caused by radiation or chemical mutagens

23.  Mutations can be grouped according to
 Their size
 The Type of Cell Involved
 Mode of Origin
 Direction of Mutation
 Phenotypic Effects

24.  1. Spontaneous mutations The spontaneous mutations
occur suddenly in the nature and their origin is unknown.
They are also called “background mutation” and have
been reported in many organisms such as, Oenothera,
maize, bread molds, microorganisms (bacteria and
viruses), Drosophila, mice, man, etc.
2. Induced mutations Besides naturally occurring
spontaneous mutations, the mutations can be induced
artificially in the living organisms by exposing them to
abnormal environment such as radiation, certain physical
conditions (i.e., temperature) and chemicals.

25.  Mutations can be grouped according to
 Their size
 The Type of Cell Involved
 Mode of Origin
 Direction of Mutation
 Phenotypic Effects

26. 1. Forward mutations In an organism when
mutations create a change from wild type to abnormal
phenotype, then that type of mutations are known as
forward mutations..A forward mutation takes place in
the in E. coli, inactivates the gene and makes it unable
to grow in a medium containing lactose
2. Reverse or back mutations The forward
mutations are often corrected by error correcting
mechanism, so that an abnormal phenotype changes
into wild type phenotype.

27.  Mutations can be grouped according to
 Their size
 The Type of Cell Involved
 Mode of Origin
 Direction of Mutation
 Phenotypic Effects

28. 1. Morphological mutations
Mutations that affect the visible form properties of an
organism change in size, shape (normal wing vs. curly wing
in fruit flies)
2. Lethal mutations
Are mutations that affect the viability of the organism (i.e.
Manx cat).
3. Conditional mutations
Are mutations in which the mutant allele causes the
mutant phenotype only in certain environments (called the
restrictive condition).

29. 4. Biochemical mutations
Are mutations that may not be visible or affect a
specific morphological characteristic but may have
a general affect on the ability to grow or proliferate.

30. Thank you