Chromosomal Mutations Flashcards
Name three types of chromosomal abnormalities and what they do
Numerical means the wrong number of chromosomes
Structural means large scale rearrangements
Mutational means small scale, base level changes
What chromosome is affected by Down syndrome and what are he effects of this?
Autosomal aneuploidy syndrome Trisomy 21 Characteristic face dysmorphologies Lower IQ Lower life expectancy Alzheimer’s disease in later life
What chromosome is affected in Patau’s syndrome and what are the effects of this?
Autosomal aneuploidy syndrome Trisomy 13 Dysmorphic features Mental retardation 5% die in first month of life, rest die under a year
What chromosome is affected in Edwards syndrome and what are the effects of this?
Autosomal aneuploidy syndrome
Trisomy 18
Severe developmental problems
Most die within first year of life
What chromosome is affected in Turner syndrome and what are the effects of this?
Sex chromosome aneuploidy syndrome 45 X 97% conception result in spontaneous loss Females of short stature and infertile Neck webbing and wide spaced nipples Intelligence and lifespan is normal
What chromosome is affected in Klinefelter syndrome and what are the effects of this?
Sex chromosome aneuploidy syndrome 47 XXY Tall stature and long limbs Infertile makes with small testes 50% chance of gynaecomastia Mild learning difficulties
What is balanced translocation and how is it different to unbalanced translocation?
The correct number and identity of the chromosomes is the same but the arrangement is different.
Unbalanced is the incorrect number and identity of chromosomes.
They are both reciprocal translocation.
What is robertsonian translocation?
Occurs in acrocentric chromosomes and leaves one chromosome with all the functional DNA (two long arms) and one with no functional DNA (two short arms).
Usually results in trisomy and 1 in 6 chance of Down syndrome.
What are three other mutations of chromosomes?
Deletion is deleted generic material.
Inversions are DNA turned around (balanced rearrangement) and can involve the centromere.
Insertions are addition of chromosomal information.
What types of genetic mutations are there?
Non coding
Coding such as
Silent which means there is no change in the encoded amino acid
Missense which means there is a change in the encoded amino acid
Nonsense means an amino acid is replaced with a stop codon.
Frameshift mutations are deletions and insertions and usually lead to a stop codon.
What are two types of point mutations?
Transitions Purine to purine (A-G) Pyrimidine to pyrimidine (C-T) Transversions Purine to pyrimidine (A-C) Pyrimidine to purine (C-G)
What does the name Cys64Arg tell you?
The amino acid is meant to be Arg but 64th is now Cys.
What does the name M252X mean?
Methionine at 252 has been replaced by a stop codon.
What are five ways of detecting mutations?
PCR Gel electrophoresis DNA sequence Restriction fragment length polymorphism Amplification Refractory Mutation system
What are three steps of PCR?
DNA denatured at 93-95 degrees
Annealed at 50-70 degrees
DNA extended by DNA polymerase at 70-75 degrees
This is repeated 20-30 times.
