1. Hawler Medical University
Molecular Basis of Mutation
Bashdar M. Hussen
MSc.Biotechnology
Hawler Medical University

2. What Are Mutations? Changes in the nucleotide sequence of DNA
May occur in somatic cells (aren’t passed to offspring)
May occur in gametes (eggs & sperm) and be passed to offspring

4. What Causes Mutations? There are two ways Mutations can be inherited.
Parent to child
Mutations can be acquired.
Environmental damage
Mistakes when DNA is copied

5. Are Mutations Helpful or Harmful?
Some type of skin cancers and leukemia result from somatic mutations
Some mutations may improve an organism’s survival (beneficial)

7. Types of Gene Mutations
Include:
Point Mutations
Base Substitutions (transitions and transversions)
Base additions or deletions
Frameshift Mutation

8. Frameshift Mutation Inserting or deleting one or more nucleotides
Changes the “reading frame” like changing a sentence
Proteins built incorrectly

13. Point mutations can also be categorized functionally
Silent substitutions: the mutation changes one codon for A.A into another codon for that same A.A
Missense mutations: the codon for one amino acid is replaced by a codon for another amino acid (code for a different amino acid).
Nonsense mutations: the codon for one amino acid is replaced by a translation termination (stop) codon.

15. Point Mutation
Sickle Cell disease is the result of one nucleotide substitution (GAG to GTG)
Occurs in the hemoglobin gene

17. New mutations are categorized as induced and spontaneous
Induced mutations are defined as those that arise after purposeful treatment with mutagens, environmental agents that are known to increase the rate of mutations.
Spontaneous mutations are those that arise in the absence of known mutagen treatment

18. Spontaneous mutations and human diseases
Muscular dystrophy (CTG repeats)
Fragile mental retardation (CGG repeats )
Becker muscular dystrophy (BMD)
Dystrophin is a rod-shaped cytoplasmic protein, and a vital part of a protein complex that connects the cytoskeleton of a muscle fiber to the surrounding extracellular matrix

19. Thank You
11/29/2018