lec 3 Flashcards
(16 cards)
the typical genotyping protocol
target fragment amplification → allelic discrimination reaction (hybridization) → allele specific product identification (microarray)
hybridization
thermal stability between matched and mismatched probe and target dna is different → used to differentiate snp alleles
microarrays
probes for snps are attached to array, fluorescence can be detected, microarray scanned/read to identify snps
- genechip
GWAS - statistical analysis
- test for association of genotype with disease
- 1.33 ratio = person with that allele is 1.33 (33%) more likely to have disease
- p values are calculated using chi square analysis for each snp marker
PER1 - circadian rhythm regulation gene
A = 60% of pop and G = 40% of pop
AA - wake up 1 hour earlier then GG
AG - wake up in between
quant vs qual gene inheritance
qualitative - single gene influence, trait expression is unaffected by environmental factors (eg. huntington’s or sickle cell)
- trait either present or absent
- eg. phenylketonuria (PKU) is a single cell disorder (deficient in enzyme PDH and leads to intellectual disability)
quantitative - multiple genes influence, not simple pattern of inheritance, environment has affect (eg. depression or autism)
- trait can be a range, mild to severe
law of segregation
two alleles will separate (randomly) from each other during gamete formation, one gamete = one allele for each trait
law of indep. assortment
separation of pair of alleles for a trait has no impact on the separation of other traits
- eg. having brown hair doesn’t mean you can’t have facial tics
gene linkage and recombination
some traits are linked to other traits (red hair and light skin) → recombination is when paired chromosomes swap genetic material before crossing over
- the closer the genes are, the probability of separation is low and it will be transmitted to offspring
linkage analysis
used to find genes associated with disease, relative to known genetic markers
- applications of this can be fingerprinting (probably of two individuals having identical VNTR at 13 loci is very small)
huntington disease (recomb+link cont.)
more CAG repeat, HTT produces huntingtin protein, excess = huntington’s
- onset is 35 years but more CAG = earlier onset
- g8 marker = dna sequence linked to huntington allele
- H is dominant (HH does not survive, HD = affected)
human language and FOXP2
- mutation = language problems
- chimps and humans differ by 2 amino acids in protein sequence
gene conversion
one chromosome gives some of it’s sequence to the other, non reciprocal (it’s sequence doesn’t change)
- mechanism involves mismatch repair
chromosomal translocation (neurofibromatosis ex.)
exchange of genetic material between non homologous chromosomes
- balanced - reciprocal
- unbalanced - nonreciprocal (one gains one loses)
eg. neurofibromatosis 1
- neurofibromin = cell growth regulator
- common disease! cafe au lait skin, freckles, large head, neurocognitive deficits, etc.
genetic imprinting
- phenotypic expression is dependent on its parental origin
- angelman and prader willi are the loss of chromosomal region 15q11-13 (mother = angelman, father = prader willi)
- angelman = frequent smiling, prader = food obsession
inheritance of mitochondrial dna (leber’s hereditary optic neuropathy)
mitochondria - self replicating organelles that contain their own dna (mtdna)
- 100% maternal traits because only maternal gets transferred to offspring bc its abundant in tail of sperm not head - single lineage
leber’s hereditary optic neuropathy - mutation in mitochondria and leads to loss of vision
- probably of child getting disease depends on ratio of mutant to normal mitochondria
