Flashcards in Chromosome Abnormalities/Mutations/Analysis Deck (29)
Give the three main types of chromosome abnormalities
Give types of numerical chromosome abnormalities
Sex linked aneuploidy
Describe the mechanism of non-disjunction
Problem in meiosis to give a disomy (two copies of a chromosome in a daughter cell/gamete)
What does non-disjunction give rise to in offspring?
Trisomy (an extra chromosome in a cell)
What is caused by trisomy in chromosome 21?
Trisomy in chromosome 13?
Give some features of Patau syndrome
- dysmorphic features
- mental retardation
Features of Edwards syndrome?
- developmental problems
Features of Turner syndrome?
- short stature
- neck webbing
- widely spaced nipples
Features of Klinefelter syndrome?
- small testes
- long limbs
Give types of structural chromosome abnormalities
Balanced/unbalanced reciprocal translocation
What is reciprocal translocation?
Chromosome breaks in two and forms two new derivatives
Balanced - same amount of each at the end; phenotypically normal
Unbalanced - from normal parent and another with balanced translocation; gives rise to trisomy/monosomy in offspring
What is Robertsonian translocation?
Occurs in acrocentric chromosomes;
- long arms (q) attach to long arms
- short arms (p) attach to short arms
Gives rise to abnormalities in offspring if they receive unequal amounts of a chromosome
Give two types of inversion
Paracentric inversion - abnormal fixing, no centromere involvement
Pericentric inversion - abnormal fixing in the centromere region
Give the four types of mutational coding abnormalities
What is the difference between transitions and transversions?
Transitions - purine mutates to purine, pyrimidine mutates to pyrimidine
Transversions - purine mutates to pyrimidine, pyrimidine mutates to purine
Give types of mutational chromosome abnormalities
*All may be coding/non-coding/point mutations
Give the main types of abnormality detection
What is PCR?
Polymerase chain reaction
What happens during PCR?
- denaturation to create a single-stranded DNA
- annealing (bonding of primers to DNA template
- extension of primers using DNA polymerase to synthesise new DNA strands behind them
- repetition to amplify target DNA
- analysis using gel electrophoresis
What is ARMS?
Amplification refractory mutation system
What happens during ARMS?
- sequence specific primers will only amplify if the target allele is present
- wild type allele amplified by a normal primer
- mutant allele amplified by a mutant amplification
- then undergoes PCR and gel electrophoresis
What is RFLP?
Restriction fragment length polymorphism
What happens during RFLP?
- restriction enzyme cuts DNA strand at different lengths
- gel electrophoresis
What is DNA sequencing?
the process of determining the precise order of nucleotides within a DNA molecule