3. The term “MUTATION” was first coined by scientist
Hugo DeVries in 1901.
A mutation is a change in the genetic material.This
means changes to the DNA or to the chromosomes
which carry the DNA.These changes are heritable (can
be passed on to the next generation) unless they have
4. ROLE OF MUTATION
Ultimate source of all genetic variation and it provides
the raw material for Evolution
Some mutations lead to newer versions of proteins and
help the organisms to adapt to changes in the
environment. As the first step of evolution, the mutation
is important as it creates a new DNA sequence for a
specific gene which creates a new allele.
5. CHANGE INTHE STRUCTURE OF A
• May Involve:
– Changing the
structure of a
– The loss or gain
of part of a
Euploidy is a chromosomal variation that involves the entire
set of chromosomes in a cell or an organism. Euploidy is more
tolerated in plants than in animals.
There may be a single set (monoploidy), two sets (diploidy), or
multiple sets (polyploidy, i.E.Triploid, tetraploid, pentaploid,
Monoploids have a single basic set of
E.G.-Barleyand 10in corn.
Monoploidy is common in plant and raer in
Monoploids can be produced by artificial mean by the
1. X-rays treatment
2. Delayed pollination
3. Temperature shock (cold treatment)
4. Colchicine treatment
5. Distinct hybridization
Polyploidy occurs in cells and organisms when there are
more than two homologous sets of chromosomes.
Very common in plants – associated with origin of new
species – may positively correlate to size of individual.
There are two classes of polyploids based on the number
of chromosome sets: • . Even-number polyploids are more
likely to be at least partially fertile, because the potential
exists for equal segregation of homologs during meiosis. .
Odd-number polyploids will always have unpaired
chromosomes. Balanced gametes are rare and these
organisms are usually sterile or have increased zygote
Triploids, pentaploids (all with odd number of
chromosome sets) are often sterile due to pairing problems
15. Types of polyploidy in plants..
1.Autopolyploidy-Autopolyploids results when all sets of
chromosomes are from the same species, usually due to
Examples include: – (1) “Seedless” fruits like bananas (3n =
33), grapes and watermelons. – (2) Grasses, garden flowers,
crop plants and forest trees
2.Allopolyploidy– hybrid of two or more closely related
species – partially homologous chromosomes
(homeologous) Allopolyploidy is caused by the presence of
several genomes of different species in a cell, a tissue or a
This is a condition where the chromosome number is
not an exact multiple of the normal diploid number,
with either fewer or more than the normal number of
chromosome in the cell.
A condition of aneuploidy may occur due to loss of
one or more chromosomes during mitosis or meiosis.
18. In diploid organisms aneuploid variations take
four main forms that can be classified under
two main groups:
1. Hypoploidy: loss of one or more
chromosomes from basic set.(called
monosomy).(2n-1) or due to the lose of
one pair of chromosome called nullysomy
2. Hyperploidy: presence of one or more
chromosomes in the basic set.(called
trisomy).(2n+1).or a pair of chromosomes
19. • Change in the nucleotide sequence
of a gene
• May only involve a single nucleotide
• May be due to copying errors,
• chemicals, viruses, etc.
20. Point mutations are the most common type of
Also known as base pair substitution.
Change in a single nucleotide base pair.
Point mutation can be categorized into three
1) SILENT MUTATION
2) MISSENSE MUTATION
3) NONSENSE MUTATION
21. a.SAILENT MUTATION
A silent mutation is a change in the sequence of
nucleotide bases which constitutes DNA, without a
subsequent change in the amino acid or the function of the
overall protein. Sometimes a single amino acid will change,
but if it has the same properties as the amino acid it
replaced, little to no change will happen.
22. b.MISSENSE MUTATION: a base is substituted
that alters a codon in the mRNA resulting in a
different amino acid in the protein product
23. c.NONSENSE MUTATION: changes a sense codon
into a nonsense codon. Nonsense mutation early in the
mRNA sequence produces a greatly shortened &
usually nonfunctional protein
24. A frameshift mutation is a genetic mutation
caused by a deletion or insertion in a DNA
sequence that shifts the way the sequence is
27. According to the survival (effects),
mutations are classified into
following four types:
Lethal: A mutation which kills the individual that
Sub-lethal: When mortality is more than 50% of
individuals that carry mutation
Sub-vital: When morality is less than 50% of individuals
that carry mutation
Vital: When all the mutant individual survives
28. According to the mode of origin
mutation may be…
A. SPONTANEOUS MUTATION: The
mutation that occurs spontaneously is termed as
spontaneous mutation. Most of the mutation that
originally studied occurs spontaneously.
B. INDUCED MUTATIONS: When mutations occur
by treating an organism with mutagenizing agent
is termed as induced mutation.
29. A mutagen is any substance or agent
that can cause a mutation, or change in
the sequence or structure of DNA.
Physical mutagens • Ionizing radiations such
as X-rays, gamma rays causes DNA breakage
and other damages. • Ultraviolet radiations with
wavelength above 260 nm are absorbed strongly
by bases, producing pyrimidine dimers, which
can cause error in replication .