Mutations and Kinds of Mutations

1. Mutations
BSBT107
Presented By:
Gunjit Setia
(Integrated Btech + Mtech in Biotechnology)
Presented To:
Dr. Zeeshan Khan

2. Introduction
Mutation-
It is a change of the nucleotide sequence of the genome of an
organism, virus, or extra chromosomal genetic element.
Classes of Mutation-
 Spontaneous Mutation
These are mainly caused during DNA replication or they can naturally occur by
changes in DNA sequence during replication.
 Induced Mutation
These are caused by the changes in DNA brought by some environmental factors
(mutagens).E.g. UV light, X rays, Gamma rays, etc..
Chromosome Mutation may involve due to changing in the structure
of a chromosome or due to loss or gain of part of a chromosome.

3. Kinds of Mutation
There are 2 kinds of Mutations:
1. Chromosomal Mutation
2. Gene Mutation

4. 1. Chromosomal Mutations
• An abnormal change in
the structure of all or part
of a chromosome, OR in
the number of
chromosomes an
organism has
• Ex: normal humans have
46 chromosomes
• Humans with Down
Syndrome have 47

5. Trisomy 21

6. Down syndrome (Trisomy 21)
• Extra 21 chromosome
• Effects 1/700
• Alters child’s
phenotype–
characteristic facial
features, short stature
• Usually some degree of
mental retardation

7. 2. Gene Mutation
• A change that affects a
gene on a chromosome
• Causes the cell to
produce abnormal
proteins
• There are 2 types of
gene mutations:
1. Point Mutation
2. Frame Shift Mutation

8. Point Mutation
• A gene mutation involving only a single nucleotide
• Ex: ACA mutates to read ACT
• mRNA codes ACT to be UGA which is a stop
codon!
• This will cause the necessary protein to not be made

9. Frame Shift Mutation
• This is the insertion or deletion of one or
more nucleotides
• Ex: THE CAT ATE
• In a frame shift mutation it would read
THE ATA TE which is meaningless!
• Which letter was deleted?
• C

10. Genetic Disorders
There are 3 different types of Human
Genetic Disorders
1. Sex-linked Disorders
2. Autosomal Genetic Disorders
3. Chromosomal Genetic Disorders

11. Sex-linked Traits
• A trait that is
controlled by a gene
found on the sex
chromosome

12. Why are Males more likely to
inherit sex-linked genetic disorders?
• On the other hand, men are
more likely to inherit sex-
linked disorders because they
only have one X Chromosome
• They lack the protection of
having 2 X’s as females do.
• Each male child of a mother
who carries the defect has a
50 % risk of inheriting the
faulty gene and the disorder.
• Each female child has a 50%
chance of being a carrier like
her mother.

13. The two sex-linked disorders we
will be discussing are:
1. Color Blindness
2. Hemophilia

14. 1. Color Blindness
• Color blindness is a condition
in which the individual
cannot perceive certain colors
• Found mostly in males
• Females can carry the gene
for color blindness and are
called carriers
• Carriers have the gene for
color blindness on one X
chromosome

15. This is what a strawberry patch would
look like to a color blind person

16. 2. Hemophilia
• Hemophilia is a genetic disorder
that affects the ability of blood to
form an effective clot and thereby
results in prolonged bleeding.
• Occurs almost exclusively in males.

17. What are Autosomal Genetic
Disorders?
• Humans have 23 pairs of chromosomes
• 22 pairs are called Autosomes
• The last pair are called sex chromosomes
because they determine your gender
• Autosomal genetic disorders therefore are
mutations that occur on the first 22 pairs of
autosomes

18. An Example of an Autosomal
Genetic Disorder is:
1.Sickle Cell Anemia
• The genetic defect that causes
sickle cell anemia affects
hemoglobin, a component of red
blood cells.
• What causes this defect is a
mutation when making a certain
amino acid

19. How to Detect Genetic Disorders
During pregnancy
1. Amniocentesis

20. 1. Amniocentesis
• A long needle is inserted
into the amniotic sac of a
pregnant woman to
obtain a sample of
amniotic fluid
• The cells of the fetus that
are contained within the
fluid are then examined
to see if there are any
abnormalities