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changes in the genetic
material (DNA).
1.Gene Mutations
2.Chromosomal Mutations
Point Mutations: Changes in
one or more nucleotides
Examples
:
a. Substitutions
b. Insertions
c. Deletions
Substitutions
switch 1/few base(s) for
another
Insertions
add in an extra base
Deletions
loses a base
**Insertions and deletions
can cause a…
Frame shift when a base is
added or deleted, the bases are still
read in groups of 3 (mRNA codons),
BUT now the grouping is
shifted for every codon that
follows.
It’s like cutting in line (insertion) or
getting out of line (deletion)- everybody
else moves forward or backward
** A frame shift mutation can
alter a protein so much that it
is unable to function normally.
changes in the number or structure
of chromosomes.
Examples:
Deletion
Duplication
Inversion
Translocation
Deletion
losing a gene (AB*DEF)
genes of a chromosome are permanently lost
as they become unattached to the
centromere and are lost forever
Duplicationadding an extra copy of a gene (ABBC*DEF)
In this mutation, the mutants genes are displayed
twice on the same chromosome due to duplication of
these genes.
Inversion
flipping backwards the genes within a
chromosome (FED*CBA)
This is where the order of a particular order
of genes are reversed as seen below
Translocation-
moving genes from 1 chromosome to another
(ABC*DEF and GHI*JKL become ABC*JKL and
GH*IDEF).
This is where information from one of two
homologous chromosomes breaks and binds to the
other. Usually this sort of mutation is lethal
** Significance of Mutations:
Some have little to no effect on gene
expression or protein function.
(Example: a substitution that doesn’t
change the amino acid).
Harmful changes- disrupt normal
activities (many related to cancer).
Some are actually useful/beneficial
(example- crop plants).
A gourd-shaped tortoise is seen in Huaibei,
east China's Anhui Province, June 24, 2007.
Residents say a gene mutation contributed to
the aberration, local media reported.
(China Daily/ Reuters )