BOTECHNOLOGY IS CHALLENGING SUBJECT TO TEACH AND UNDERSTAND ALSO .....THEIR INTERESTING PART IS TO LEARN ABOUT MUTATION

1. By
TEJASWINI L. ASAWE
ASSISTANT PROFESSOR
SIDHHIS INSTITUTE OF PHARMACY
THANE

2.  Sudden heritable change in genetic material
or character of an organisms known as
mutation .
 Individuals showing these changes are known
as mutants .
 Factor or agents causing mutation are known
as mutagens
 Mutation which causes changes in base
sequence of a gene are known as gene
mutation or point mutation

3.  English farmer Seth Wright recorded case of
mutation first time in 1791 in male
lamb(young sheep) with unusual short legs
 The term mutation is coined by Hugo de Vries
in 1900.
 Systematic study of mutation was started in
1910 when Morgan genetically analyzed
white eye mutant of Drosophila (flies )
 H. J. Muller induced mutation in Drosophila
by using X- rays in 1927 ; he was awarded
with Nobel prize in 1946

4.  Most mutations have harmful effect, but
some mutations are beneficial.
 Spontaneous mutations occurs at very low
rate
 Some genes shows high rate of mutation
such genes are called as mutable gene
 Highly mutable sites within a gene are known
as hotspots.
 Mutation can occur in any tissue/cell
(somatic or germinal) of an organism

5.  Based on the survival of an individual
 1. Lethal mutation – when mutation causes death
of all individuals undergoing mutation are known
as lethal
 2. Sub lethal mutation - causes death of 90%
individuals
 3. Sub vital mutation– such mutation kills less
than 90% individuals
 4. Vital mutation -when mutation don’t affect
the survival of an individual are known as vital
 5. Super vital mutation – This kind of mutation
enhances the survival of individual

6. 1.Somatic mutation-
 A mutation occurring in somatic cell is called
somatic mutation.
2. Germinal Mutation-
When mutation occur in gametic cells or
reproductive cells are known as germinal
mutation.

7.  1.Forward mutation-
 When mutation occurs from the normal/wild
type allele to mutant allele(two or more
version of DNA sequence) are known as
forward mutation.
 2.Reverse mutation-
 When mutation occurs in reverse direction
that is from mutant allele to the normal/wild
type allele are known as reverse mutation.

8.  1.Spontaneous mutation-
 Spontaneous mutation occurs naturally
without any cause.
 The rate of spontaneous mutation is very
slow
 eg- Methylation followed by deamination of
cytosine.
 Rate of spontaneous mutation is higher in
eukaryotes than prokaryotes
 E.g. UV light of sunlight causing mutation in
bacteria

9.  Mutations produced due to treatment with
either a chemical or physical agent are called
induced mutation .
 The agents capable of inducing such
mutations are known as mutagen .
 use of induced mutation for crop
improvement program is known as mutation
breeding.
 E.g.. X- rays causing mutation in cereals or
grains .

10.  Physical agent –
 Physical agents like ultraviolet light , X- rays ,
gamma radiation , heat etc are commonly
used to induce mutation.
 Chemical agents –
 Nitrous acid , hydroxylamine , sulfur
mustard, hypoxanthine .

11.  Mutation that occurs in the absence of all
mutagenic agents are called spontaneous
mutations.
 Spontaneous mutation independent of the
environment was first produced by Salvador
Luria and Max Delbruck in 1943 by
`fluctuation test `.

12.  The bactriophage resistance E-Coli colonies
shows fluctuations When samples are plated
from separate small volume cultures
compared with test sample from single large
volume culture.
 In fluctuation test tube containing 0.5 ml cells
are incubated without phage until a certain
population size 108 cells / ml is reached.
 The cultures are then exposed to phage by
pouring each tube into agar plate containing
phage .
 The colony counts from 0.5ml cultures
compared with 10 ml sample test tube .

13.  The result shows that resistance bacteria arise
spontaneously prior to exposure to phage .
 sample cultures result is different than test
culture.
 Luria and Delbruck found that resistant mutant
fluctuated from sample to sample indicating
that mutant existed in the population prior to
exposure to the phage .
 They concluded that mutation in bacteria occur
spontaneously.

14. 18 – 24 hr old bacterial
culture with 104 cells / ml .
10ml
0.5 ml into each
tube
Incubated all test population reached to 108 cells / ml and then
exposed to the phage (bacteriophages )

15. 0.5 ml samples on each plate having phage
10 ml culture shows phage

16. •Josua Lederberg and Esther Lederberg used replica
plate technique for spontaneous mutation .
•In this technique a small number bacteria are plated on
master plate and incubated it until growth occurred.
•A sterile velvet pad on a transfer block is then used to
inoculate (infuse) each colonies from the master plate
•(inoculation is method of artificially inducing immunity
against disease)
•and on other plate which contains inhibitor or
selective agent to detect resistant (stop ) mutants.
•If mutant developed on master plate before inhibitor
exposure then resistant colonies should be at located at
same position on each replica plate .
Replica plate technique

17. • While if mutation occurred at after exposure
to inhibitor then the resistant colonies
should be at different replica plate .
• Josua and Esther Lederberg found that
spontaneous mutation occur in bacteria in
absence of a selective agent.
• After this conclusion the replica plate
technique has been extensively used as a
basic technique for mutant detection .

18. Agar plate
Sterile velvet plate
Master plate Replica plate