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Name some inhibitors of Taq-Polymerase


  • haem compounds from blood
  • bile salts from faeces and plant material
  • complex polysaccarides from faeces and plant material
  • humic substances from soil, extracted from bone
  • urea from urine
  • melanin from hair and skin
  • blue dye from clothing
  • collagen from tissue and bones
  • ions (Ca and Mg) in high concentration
  • EDTA, as it removes ions


Name confirmatory tests for blood

  • mRNA
    • SPTB
    • PBGD
    • ALAS2
    • HBA
  • flow immunochromatographic strip tests against glycophorin A


What is the defendant's fallacy?

"If the match probability for a DNA profile was 1 in 27 milion" and you were in a town of 54 milion, that does not mean that this other person could have done it.
It's not even sure whether that person would exist, and if yes, which age and sex it would have and whether it would have had the opportunity to commit the crime.


Name the three hierarchies of propositions:

  1. source level
    • from which individual did the biological material originate?
  2. activity level
    • what activity led to the deposition of the biological material?
  3. offence level
    • did the suspect commit the offence?


Name presumptive tests for sailva

  • ALS plus UV light --> blue-white
  • starch-iodine test
    • alpha amylase breaks down starch
    • add iodine
    • if clear, starch broken down --> saliva
  • starch with dye:
    • starch breakdown --> colour change
    • takes 30 min


What produces false positive results for presumptive blood tests?

Anything with a peroxidase activity


Name presumptive tests for semen

  • ALS e.g. with UV light --> blue
  • alpha-napthyl phosphate plus Brentamine Fast Blue detect Seminal acid phosphatase SAP


Name confirmatory test for saliva

  • antibody strips
  • mRNA


Name confirmatory tests for semen

  • Visualisation of spermatozoa
    • Haematoxilin plus eosin
    • christmas tree stain
  • immunochromatographic strip test against PSA (works even in azoospermic samples)
  • mRNA
    • PRM1, 2
    • PSA


What properties need genetic markers for species identification?

  • They need to be stable enough to readily identify the species
  • but also variable enough to allow identification of indivuals


Why would one type non-human samples in forensics?

  • possession of protected species
  • crimes against people or property (e.g. animal hair left by perp)
  • crimes against animals


What is the prosecutor's fallacy?

Also called transposed conditional

"The statement 'the probability of gaining this DNA profile if it came from someone other than the suspect is 1 in 1 million', does not mean that 'the probability that the evidence came from someone other than the suspect is 1 in 1 million'."


Name methods for DNA quantification


  • Visualisation on agarose gel
  • ultraviolet spectrophotometry
  • fluorescence spectrophotometry
  • hybridisation
  • real-time PCR
  • DNA IQ Isolation System


Name presumptive tests for blood

  • ALS at 415nm
  • Luminol plus hydorogen peroxide -> in presence of haemoglobin --> chemiluninescence
  • Fluorescin + ALS 450nm
  • Leucomalachite green --> green
  • phenolphthalein (Kastle Meyer) --> pink
  • tetramethylbenzidine (TMB) --> green


What is the difference between random match probability and likelihood ratio?

  • RMP: chance that the sample came from a random person is in the order of 1:xyz
  • LR: the result is xyz times more likely if DNA came from suspect than from sombody unrelated


What produces false positive results for semen presumptive tests?

anything with acid phosphatases


Name the conditions that have to be fullfilled for Hardy Weinberg Equilibrium

  •  population is infintely large
  •  random mating
  •  no migration
  • no natural selection
  • no mutations