Mutations and genetic analysis Flashcards
3 types of chromosomal abnormalities
Numerical
Structural
Mutational
When is there a high incidence of mutation in pregnancy
First trimester with trisomy
Mostly maternal non disjunction syndromes - trisomy
Patau - extra 13
Edwards - extra 18
Down - extra 21
Klinefeller - XXY
Monosomy
Turners have one X
Downs syndrome
Advancing maternal age and problem with non disjunction
Facial dysmorphologies, 50-60 years and alzheimers
Patau syndrome
5% die in first month and due to non disjunction
Edwards syndrome
Developmental problems
Turners syndrome
Short females with neck webbing and wide spaced nipples who are infertile
Normal intelligence and lifespan
Klinefeler Syndrom
Gynaecomastia and are tall with long limbs and small testes with mild learning difficulties
Balanced
All genetic information still present but just in the wrong place
Robertsonian translocation
fuse 2 acrocentric chromosomes can lead to downs syndrome
Reciprocal translocation
Partial monosomy or trisomy
Paracentric inversion
Not too harmful
Pericentric inversion
Include centromere
Transition point mutation
Purine=> purine
Pyrimidine => pyrimidine
Transversion point mutation
purine<=> pyrimidine
PCR requirements
Heat tolerant Tac polymerase and polymerase
Sequence information and DNA
Oligonucleotide primers
Nucleotide
Name some uses of PCR
DNA cloning
In vitro mutagenesis
Forensic medicine
Gene identification for mutations
Name the 3 consecutive temperatures for denaturing, annealing and extending the DNA
93-95
50-70
70-75
Gel electrophoresis
Separate compounds on size and density
Apply electric field over agarose gel and negative DNA ==> positive electrode
What are some advantages of PCR
Fast, easy to use, sensitive and robust
ARMS
Like PCR but a different primer used to detect single base mutations and deletions
In ARMS explain the link between wild type allele and primer
Normal = Amplified Mutant = not amplified
In ARMS explain the link between mutant allele and primer
Normal primer = no amplification
Mutant primer = amplification
Advantages of ARMS
Cheap and no label needed
State some slight drawbacks of ARMS
Electrophoresis also needed and the primer design is critical
State the disadvantages of ARMS
Need sequence information
Limited amplification size
Limited amounts of product
Infidelity of DNA replication
Restriction endonuclease
Enzyme used in RFLP from bacterial cell that always cuts DNA at the same sight by recognising specific parts of DNA and degrades DNA of incoming virus
Protective mechanism
Explain some positives/negatives of RFLP
Simple cheap and non radioactive
When electrophoresis is not always feasible
DNA sequencing
Precise order of nucleotide
ddNTP’s
Chain elongating inhibitors of DNA polymerase
Some negatives/positives of DNA sequencing
Gold standard
Extensive equipment required and has poor quality read ( 70-900) bases
What do you base the decision on which mutation detecting method is used?
Sensitivity and specifity
