Genetic Analysis And Disease Flashcards
What produces genetic variations which influence our ability to survive/ influence susceptibility to disease
Recombination and unequal crossing over
What does haplotype mean
Sets/blocks of polymorphic markers such as SNPs inherited together
Why are repeats such as VNTRs mad micro satellites described as in polymorphic loci?
They vary in position and size on chromosomes due to unqualified sister chromatids crossing over
What are micro satellites (2 types)
Simple sequence repeats ssr
Or short tandem repeats which vary in individuals so is used for identifying individuals
How do minisatellites differ
Longer than micro satellites and are GC rich and are at subtelocentric region of chromosome
Briefly explain the old technique of dna fingerprinting
Dna fragments cut using restriction endonucleases which cut at the tandem repeats (identify them)
Fragments seperated via size in gel electrophoresis once the repeats are hybridised with PROBES
Southern blotting used
Probes are seen under the UV light in the gel
How is PCR and primers now used for genetic fingerprinting to identify areas of repeats
Primers flank position of the repeats and this is them amplified
The size of the PCR product shows how long the repeats were
What are single nucleotide polymorphisms
Single base changes between individuals usually inherited in the haplotype
How do SNPs create RFLPs restriction fragment length polymorphisms
SNPs can produce RFLPs but removing or adding endonucleases recognition sites
When seperated in eg dna fingerprinting the fragments will then vary in size between individuals depending on SNPs = rflps
What was used to clone and map the CF gene to identify the mutation phe58
It was cloned and positioned using RFLP analysis and linkage
How can SNPs and snp maps be used as a diagnostic tool
Through sequencing we identified SNPs and their locations. We can look for the association of SNPs with a phenotype eg for a disease
Then can identify the genes associated by using cpg islands and looking at position of SNP
How would you identify where genes are in a DNA sequence to look at what is associated with an SNP
Genes are at cpg islands
Cpg are CG rich regions where the promoter begins transcription of a gene
If you didn’t know the sequence of the dna how would you locate a gene
Using endonucleases which cluster at the promoter region of a gene
How are SNPs analysed (to identify the base change)
The genome is amplified using PCR
The dna is then fragmented and primers are added 1 nucleotide before an SNP
1 nucleotide is then added which is labelled
The label can be then read and identifies the base added
What is a genome wide association study
Looking at snp maps around the world to see if there is significant association of an SNP or haplotypes with specific phenotypes
