5. ¤ Introduction of mutations
¤ Types of mutations
¤ Chromosomal mutation
¤ Point mutation
¤ Types of point mutations
¤ Causes of mutations
Contents
6. 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
8. Chromosome Mutations
• May Involve:
• Changing in the number of
chromosomes Lose or se
gain of chromosomes e.g.
• Down’s syndrome .
• Change in the structure of
chromosomes
–gfgfgfggfgfgfgfghgfgvggfff
9. Chromosome Mutations
• Down Syndrome
– Chromosome 21 does not separate
correctly.
– They have 47 chromosomes in
stead of 46.
– Children with Down Syndrome
develop slower, may have heart
and stomach illnesses and vary
greatly in their degree of
inteligence.
10. Chromosome Mutations
• Due to change in structure.
–Deletion
–Inversion
–Translocation
–Nondisjunction
–Duplication
17. Point Mutations
• Silent mutation = no change to protein
AUGCGUGUAUACGCAUGCGAGUGA
MetArgValTyrAlaCysGluStop
AUGCGUGUAUACGCUUGCGAGUGA
MetArgValTyrAlaCysGluStop
18.
19. Point Mutation
• Sickle Cell disease is
the result of one
nucleotide
substitution
• Occurs in the
hemoglobin gene
23. Sickle cell anemia
• Hemoglobin protein in red blood cells
– strikes 1 out of 400 African Americans
– limits activity, painful & may die young
Normal
round cells
Misshapen
sickle cells
Only 1 out of
146 amino acids
24. Point Mutations
• Nonsense mutation = change to STOP
AUGCGUGUAUACGCAUGCGAGUGA
MetArgValTyrAlaCysGluStop
AUGCGUGUAUAAGCAUGCGAGUGA
MetArgValStop
Really destroyed
that protein!
25.
26. Frameshift Mutations
• Add or delete one or more bases
– changes the meaning of the whole protein
THEFATCATANDTHEREDRATRAN
THEFATCANTANDTHEREDRATRAN
THEFATCAANDTHEREDRATRAN
OR
Add one!Delete one!
Does this change
the sentence?
A LOT!
27. Frameshift Mutations
• Addition = add one or more bases
AUGCGUGUAUACGCAUGCGAGUGA
MetArgValTyrAlaCysGluStop
AUGCGUGUAUACGUCAUGCGAGUGA
MetArgValTyrValMetArgValA
28. Frameshift Mutations
• Deletion = lose one or more bases
AUGCGUGUAUACGCAUGCGAGUGA
MetArgValTyrAlaCysGluStop
AUGCGUGUAUACGAUGCGAGUGA
MetArgValTyrAspAlaSerGA
30. Causes of Mutations
• Chemical cause the mutations are called
Mutagens. like
• Ionizing radiation
• Alpha, beta, gamma and cosmic rays.
• Nonionizing radiation
• Uv light,
• Chemical mutagens
• Nitrous acid, Hydroxylamine
31. Example of chemical mutations
30/10/2015
Mrs Smith: Ch13: Mutations an
Chromosomal Abnormalities
31