m u t a t i o n
TRANSCRIPT
M U T A T I O N
Sub-Topics
Mutation classification and types
Gene mutation
Chromosomal mutation
7.1
7.2
7.3
7.1Mutation
Classification and Types
Learning Outcomes
• Define mutation (C1)
• Classify mutation to (C1)
– Gene/point mutation
– Chromosomal mutation
• State two types of mutation (C1)– Spontaneous mutation
– Induced mutation
• Define mutagen (C1)
• State types of mutagen (C1)– Physical
– chemical
Mutation classification and types7.1
What is
mutation
?
• A sudden random change in
genetic material of a cell that
potentially can cause differ in
appearance or behavior from
normal type.
What is mutation?
● This alteration can be pass from mother
to daughter cell during cell division.
● If mutation occur in reproductive cell,
it may be passed from parent to
offspring.
Classification of mutation
Types of mutation
SPONTANEOUS MUTATION
INDUCED MUTATION
A mutation occurring in
the absence of mutagens,
usually due to errors in the
normal functioning of cellular
enzymes.
e.g. non-disjunction
A mutation caused by
exposure to mutagens.
What is
mutagen?
Mutagen?● An agent that
cause an increase
in number of
mutants in a population.
● A mutagen is anything
that changes the genetic
material of an organism.
Types of
mutagen
•PHYSICAL MUTAGEN•UV rays
•Gamma rays•X-rays
•CHEMICAL MUTAGEN•Colchicine
•Ethidium bromide
7.2Gene Mutation
Learning Outcomes
• Define gene mutation (C1)
• State the four types of gene mutation (C1)
• Explain four types of gene mutation (C2)
- Base substitution
- Base insertion
- Base deletion
- Base inversion
Gene mutation7.2
Learning Outcomes
• Explain base substitution (e.g. sickle cell anaemia as missense mutation) (C2)
• State the effect of base substitution (missense, nonsense and silent mutation) and base insertion and base deletion (frameshift mutation) (C1)
• Explain base insertion and base deletion as a frameshift mutation (C2)
Gene mutation7.2
Gene Mutation
• Caused by change in nucleotide sequence of DNA within a gene.
Thymine
Cytosine
Gene Mutation
RESULT => change in amino acid sequence of polypeptide and thus different type of protein produced with abnormal function
Types of gene mutation
Base substitution may lead to missense mutation.It can cause disease such as sickle cell anaemia
Effect of base substitution
Base insertion and base deletion can
cause FRAMESHIFT mutation
What is frameshift mutation?
A type of gene mutationwhere in the addition (insertion) or deletion
of (a number of) nucleotide(s)causes a shift in the reading frame of the codons
in the mRNA,thus, may eventually lead to the alteration
in the amino acid sequence at protein translation.
M U T A T I O N
7.3Chromosomal
Mutation
Learning Outcomes
• Define chromosomal mutation (C1)
• State two types of chromosomal mutation (C1)
– Changes in chromosomal structure
– Changes in chromosomal number
• Explain changes in chromosomal structure / chromosomal aberration (C2)
• Explain types of chromosomal aberration (C2)- Translocation- Deletion (segmental
deletion) (eg. cri du chat)- Inversion- Duplication
Chromosomal mutation7.3
Learning Outcomes
• Explain alteration of chromosome number (C2)
• State the types of the alteration (C1)– Aneuploidy– Euploidy / polyploidy
• Explain aneuploidy (C2)• State aneuploidy effect on
autosomal chromosome (Monosomy 21 and Trisomy21) and sex chromosome (Klinefelter and Turnersyndrome) (C1)
• Explain autosomal abnormalities and their effects: (C2)
⮚ Monosomy (monosomy 21)
⮚ Trisomy (Down syndrome / trisomy 21)
• Explain sex chromosomalabnormalities: (C2)
⮚ Klinefelter syndrome (47, XXY)
⮚ Turner syndrome (45, XO)
• Explain euploidy/polyploidy: (C2)
⮚ Autopolyploidy
⮚ Allopolyploidy
Chromosomal mutation7.3
Chromosomal mutation?
• is any change or error that occurs within thechromosome.
• occur and change the entirety of the chromosomeitself.
Classification of Chromosomal Mutation
chromosomal
mutations
polyploidy
(euploidy)
aneuploidy
change in
structure(chromosomal aberration)
change in DNA
involving
more than one locus
change in
number
allopolyploid
y
autopolyploi
dy
translocati
on
duplication
deletion
inversion
Any changes in the normal structure of
chromosomes; often results in physical or
mental abnormalities
Types of chromosomal aberration:
- Translocation
- Deletion (segmental
deletion)
- Inversion
- Duplication
Chromosomal aberration
Types of Chromosomal aberration
Alteration of chromosome number
▪ Due to the changes in the number of chromosomes
▪ Results of errors/non-disjunction occurringduring meiosis
▪ Also may occur during mitosis
▪ May involved loss or gain of single chromosomes🡪 aneuploidy (2n+1 or 2n-1)
▪ Or increased in entire haploid sets of chromosomes🡪 euploidy (3n, 4n, 5n…)
Normal Karyotype
Effect of aneuploidy on autosomal chromosome
Monosomy 21
Effect of aneuploidy on autosomal chromosome
Trisomy 21 / Down syndrome
Effect of aneuploidy on sex chromosome
Klinefelter syndrome
Effect of aneuploidy on sex chromosome
Turner syndrome
Condition when a cell or an organism has extra one or more than one complete set of chromosomes.
Euploidy/polyploidy
2n
3n
= 6 chromosomes
= 12 chromosomes
Autopolyploidy
Allopolyploidy
Autopolyploidy vs Allopolyploidy
Autopolyploidy Allopolyploidy
Autopolyploidy occurs when an individual has more than two sets of chromosomes, both of which derived from the same parental species
Allopolyploidy occurs when an individual has more than two sets of chromosome which derived from different species