Molecular Biology - Mutation and its types...........

1. MUTATION
PRESENTATION BY:
AZMATHULLAH.R.
M.Sc.MGMD – I Yr
Sub-Medical Genomics

2. DEFINITION – MUTATION
 Mutation, an alteration in the genetic material (the
genome) of a cell of a living organism or of a virus
that is more or less permanent and that can be
transmitted to the cell’s or the virus’s descendants.
 Mutation is a change in a DNA sequence.
 It can result from DNA copying mistakes made during
cell division, exposure to ionizing radiation, exposure
to chemicals called mutagens, or infection by viruses.

4. TYPES OF MUTATION– @ DNA LEVEL
• Substitution: base is replaced by one of the other three bases
• Deletion: block of one or more DNA pairs is lost
• Insertion: block of one or more DNA pairs is added
• Inversion: 180˚ rotation of piece of DNA
• Reciprocal translocation: parts of nonhomologous
chromosomes change places.
•Chromosomal rearrangements: affect many genes at one time.

6. TYPES OF MUTATION– @ PROTEIN LEVEL
Missense mutation : changes an amino acid to another
amino acid. This may or may not affect protein function,
depending on whether the change is “conservative” or
“nonconservative,” and what the amino acid actually does.
Silent mutation: does not change an amino acid, but in
some cases can still have a phenotypic effect, e.g., by
speeding up or slowing down protein synthesis, or by
affecting splicing.
Frameshift mutation: Deletion or insertion of a number of
bases that is not a multiple of 3. Usually introduces
premature STOP codons in addition to lots of amino acid
changes

9. WHAT IS A MUTAGEN?
 In simple language, we will say that
mutagens are the agents that damage
our genetic material, usually DNA,
and result in genetic abnormalities–
either inherited or non-inherited.

10. TYPES OF MUTAGENS:-
Three different types of common mutagens:-
Physical Agents: It includes high energy radiations such as gamma
rays, X- rays and alpha particles and increase in temperature.
Chemical Agents: They are of various types such as nitrous acid,
alkylating agents, acridines, and base analogues.
Biological Agents: It includes viruses, bacteria, and transposons.

11. Physical Mutagenic Agents:-
 High Energy Radiation:-
UV rays, X-rays, alpha rays, neutrons, and other ionising
and non-ionizing radiations are mutagenic
 Temperature:-
The rise in temperature results in the breakage of hydrogen
bonds present in the DNA and it becomes denatured- two single-
stranded DNA. Also, extreme heat damages DNA and breaks the
phosphodiester bonds

12. Chemical Mutagenic Agents:-
 Base Analogs
The base analogs are chemicals like the bases of DNA-
purine, and pyrimidines or structurally resemble the DNA bases.
 Alkylating Agents
Ethyl nitrosourea, poison gas, diethyl sulphate (DES),
dimethyl nitrosamine(DMN), methylhydrazine, temozolomide,
dacarbazine, busulfan, Ethyl ethane sulfate (EMS) and vinyl
chloride are common alkylating agents

13. Biological Mutagenic Agents :-
 Virus
 Bacteria
 Transposons

14. CAUSES
OF
MUTAGENS:-

15. Mutagenic Effect:-
 The mutagens are genotoxic- harmful to our DNA in some
ways; some directly affect the DNA some indirectly.
 The mutagens can alter the structure or number of
chromosomes. As deletion, insertion, duplication,
translocation, monosomy, & nondisjunction are a number of
the chromosomal abnormalities produced by mutagens.
 The mutagens also affect or dysregulate the molecular central
dogma process- replication, transcription, & translation.
 At the molecular level, the mutagens create different gene
mutations that end up in the loss of function, altered function,
or non-functional protein.