1. Mutation Lecture 11 By Ms. Shumaila Azam
Genomics
Mutation
Lecture 11
By Ms. Shumaila Azam

2. Mutation Changes in the nucleotide sequence of DNA
May occur in the somatic cells
These mutations may not pass to the off springs
May occur in gametes (ova and sperm)
These mutations may pass to the off springs

3. Are mutations helpful or harmful???
Mutations happen regularly
Almost all mutations are neutral
Chemicals and UV radiations can cause mutations
Many mutations are repaired by enzymes

4. Some type of skin cancer and leukemia result from somatic mutations.
Some mutations may improve an organism’s survival(beneficial).

5. Classes of mutation
Spontaneous mutation
Induced mutation

6. Spontaneous mutation
They are caused during the DNA replication or by incorporation of incorrect nucleotide in the growing DNA chain.
They occur naturally by changes in DNA sequences during replication.

7. Induced mutations
These mutations are caused by the changes in the DNA brought about by some environmental factor called mutagens.
E.g. UV rays, X-rays, gamma rays etc.

8. Types of mutation
Chromosome mutation
Gene mutation

9. Chromosomal mutation Changing the structure of chromosome
The loss or gain a part of a chromosome

10. Types
Deletion
Inversion
Translocation
Non disjunction
Duplication

14. Translocation It involves two chromosomes that are not homologous.
Part of one chromosome is transferred to another chromosome.

15. Non disjunction Failure of chromosomes to separate during meiosis.
Causes the gametes to have too many or too few chromosomes.
Disorders
Klinefelter’s syndrome-XXY chromosomes
Down syndrome- three 21st chromosomes
Turner syndrome- single X chromosome

22. Gene mutation Change in the nucleotide sequence of a gene
May only involve a single nucleotide
May be copying errors, chemicals, viruses

23. Types of gene mutation Point mutations Substitution Insertion Deletion
Frameshift

24. Point mutation Change of a single nucleotide
Include insertion deletion, substitution of one nucleotide in a gene.

25. Point mutation
Sickle cell disease is the result of one nucleotide substitution
Occurs in the hemoglobin gene

26. Frameshift mutation Inserting or deleting one or more nucleotides
Changes the reading frame like changing a sentence
Proteins built incorrectly