Mutations are changes in the nucleotide sequence of DNA that can ultimately change phenotypes. Mutations can occur in somatic cells or gametes and be passed to offspring. Most mutations are neutral or repaired by enzymes, but some can be harmful, like those that cause cancers, or beneficial by improving survival. There are two main types of mutations: chromosomal mutations, which involve changes in chromosome structure like deletions or duplications; and point mutations, where a single nucleotide is changed, as in sickle cell disease. Point mutations can be missense, nonsense, or frameshift, all of which can result in defective proteins if they occur in genes.

1. Subject: Advances in Molecular Genetics.
Presented To: Dr. Ali Raza Awan.
Presented By: Rimsha Khan.
(Ph.D Molecular Biology & Biotechnology)
MUTATIONS

2. WHAT ARE MUTATIONS?
• Changes in the nucleotide sequence
of DNA that ultimately reflects
the changes in phenotype.
• May occur in somatic cells (aren’t
passed to offspring)
• May occur in gametes (eggs &
sperm) and be passed to offspring

3. ARE MUTATIONS HELPFUL OR
HARMFUL?
• Mutations happen regularly
• Almost all mutations are neutral
• Chemicals & UV radiation cause
mutations
• Many mutations are repaired by
enzymes
• Variances help in natural selection
and survival

4. 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)

5. CENTRAL DOGMA
Transcription Translation
DNA m RNA PROTEINS

6. TYPES OF MUTATIONS
1. CHROMOSOMAL MUTATIONS
2. POINT MUTATIONS

7. CHROMOSOME MUTATIONS
• May Involve:
• Changing the
structure of a
chromosome
• loss or gain of
part of a
chromosome

8. CHROMOSOME MUTATIONS
Five types exist:
• Deletion
• Inversion
• Translocation
• Nondisjunction
• Duplication

9. DELETION
• Due to breakage
• A piece of a chromosome is lost

10. INVERSION
• Chromosome segment breaks off
• Segment flips around backwards
• Segment reattaches

11. DUPLICATION
• Occurs when a gene sequence is repeated

12. TRANSLOCATION
• Involves two chromosomes
that aren’t homologous
• Part of one chromosome is
transferred to another
chromosomes

13. TRANSLOCATION

14. NONDISJUNCTION
• Failure of chromosomes to
separate during meiosis
• Causes gamete to have too
many or too few chromosomes

16. CHROMOSOME MUTATION
ANIMATION

18. GENE MUTATIONS
• Change in the nucleotide
sequence of a gene
• May only involve a single
nucleotide. So these are also
called Point Mutations.
• Occurs due to copying errors,
chemicals, viruses, etc.

19. POINT MUTATION
• Change of a single nucleotide
• Includes the deletion,
insertion, or substitution of
ONE nucleotide in a gene

20. EXAMPLE OF POINT MUTATION
• Sickle Cell disease
is the result of one
nucleotide
substitution
• Occurs in the
hemoglobin gene

21. TYPES OF POINT MUTATIONS
Include:
• Missense Mutations
• Nonsense Mutations
• Frame shift Mutations

22. MISSENSE MUTATIONS
• Sense of codon is missed.
• Misfolded proteins.
• Affects folding structures of proteins
• Protein degradation/ Malfunctioning
• CAT CAT CAT CAT (histidine)
• CAT CGT CAT CAT
(pro)

23. NONSENSE MUTATIONS
• It produces Shorter/Truncated Proteins
• Results in defected proteins
• Stop codons are involved
• Signals of protein formations to ribsosomes blocks.
• Protein degradation/ Malfunctioning
• Sense of codons is completely blocked
• CAG CAG CAG CAG (glutamin)
• CAG TAG CAG CAG
• UAG

24. FRAMESHIFT MUTATION
• Inserting or deleting one or more
nucleotides
• Changes the “open reading frame”
(ORF) like changing a sentence.
• Proteins built incorrectly.
• Most dangerous.

25. FRAMESHIFT MUTATION
• Original:
• The fat cat ate the wee rat.
• Frame Shift (“a” added):
• The fat caa tet hew eer at.

26. AMINO ACID SEQUENCE
CHANGED

27. GENE MUTATION ANIMATION

28. ANY QUESTION?