Types of mutations
Transcript of Types of mutations
Point Mutations
Presented by:
Muzhar Ali 4028
Ali raza 4029
Presented To:
DR.M.Javed Iqbal
Siddiqui
¤ Introduction of mutations¤ Types of mutations¤ Chromosomal mutation ¤ Point mutation¤ Types of point mutations¤ Causes of mutations
Contents
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
Types of Mutations
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
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.
Chromosome Mutations
• Due to change in structure.–Deletion–Inversion–Translocation–Nondisjunction–Duplication
Chromosome Mutation Animation
Point Mutation
• Change of a single nucleotide• Includes the deletion,
insertion, or substitution of ONE nucleotide in a gene
–Point Mutations– Base Substitution–Silent mutation– Sense mutation –Nonsense mutation
Mutations: SubstitutionsSubstitution mutation
GGTCACCTCACGCCA ↓
CCAGUGGAGUGCGGU
↓Pro-Arg-Glu-Cys-Gly
Substitutions will only affect a single codonTheir effects may not be serious unless they affect an amino acid that is essential for the structure and function of the finished protein molecule (e.g. sickle cell anaemia)
Normal geneGGTCTCCTCACGCCA
↓CCAGAGGAGUGCGGU
Codons ↓
Pro-Glu-Glu-Cys-GlyAmino acids
© 2010 Paul Billiet ODWS
Point Mutations • Silent mutation = no change to protein
AUGCGUGUAUACGCAUGCGAGUGA
MetArgValTyrAlaCysGluStop
AUGCGUGUAUACGCUUGCGAGUGA
MetArgValTyrAlaCysGluStop
Point Mutation
• Sickle Cell disease is the result of one nucleotide substitution• Occurs in the
hemoglobin gene
Fig 4.4
Point Mutations • Missense mutation = changes amino acid
AUGCGUGUAUACGCAUGCGAGUGA
MetArgValTyrAlaCysGluStop
AUGCGUGUAUACGUAUGCGAGUGA
MetArgValTyrValCysGluStop
Sickle cell anemia• Hemoglobin protein in red blood cells– strikes 1 out of 400 African Americans– limits activity, painful & may die young
Normalround cells
Misshapensickle cells
Only 1 out of146 amino acids
Point Mutations • Nonsense mutation = change to STOP
AUGCGUGUAUACGCAUGCGAGUGA
MetArgValTyrAlaCysGluStop
AUGCGUGUAUAAGCAUGCGAGUGA
MetArgValStop
Really destroyedthat protein!
Frameshift Mutations • Add or delete one or more bases– changes the meaning of the whole protein
THEFATCATANDTHEREDRATRAN
THEFATCANTANDTHEREDRATRAN
THEFATCAANDTHEREDRATRANOR
Add one!Delete one!
Does this changethe sentence?A LOT!
Frameshift Mutations • Addition = add one or more bases
AUGCGUGUAUACGCAUGCGAGUGA
MetArgValTyrAlaCysGluStop
AUGCGUGUAUACGUCAUGCGAGUGA
MetArgValTyrValMetArgValA
Frameshift Mutations • Deletion = lose one or more bases
AUGCGUGUAUACGCAUGCGAGUGA
MetArgValTyrAlaCysGluStop
AUGCGUGUAUACGAUGCGAGUGA
MetArgValTyrAspAlaSerGA
Gene Mutation Animation
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
Example of chemical mutations
02/05/2023 Mrs Smith: Ch13: Mutations an Chromosomal Abnormalities 31