FG CA1 (1-2.3)

STR analysis features

Robust, results easily compared, discriminatory, cheap and sensitive.

SNP (Single nucleotide polymorphisms)

Single base differences in DNA. Formed by mutation sas cell goes through DNA replication. Useful for degraded DNA.

Blood collection

- Liquid syringed with anticoagulant or swabbed and air dried.
- Stains are swabbed, scraped, lifted with tape, cut out, or completely packaged.
- Knife in box and immobilized.
- Paper to prevent transfer.

FTA cards

- Used for blood and buccal samples.
- Stored at room temp for years.
- Cellulose paper impregnated with chemicals that lyse cells.

Blood presumptive tests

- UV light
- Luminol, oxidized and emits light in presence of hemoglobin
- Chemical, Phenophthalein (colourless to pink)

Semen presumptive tests

- UV
- Detection of seminal acid phosphatase (SAP), catalyse hydrosis of organic phosphate reats with brentamine fast blue. Colour to purple.

saliva presumptive test

- UV
- Alpha amylase using starch iodine test, paper made of starch with blue dye, pressed onto stain, amylase digests starch releasing dye.

Urine presumptive tests

- UV

Blood confirmatory test

lateral flow immunochromatographic strips, Glycophorin A

Saliva confirmatory test

lateral flow immunochromatographic strips, Amylase

Semen confirmatory test

lateral flow immunochromatographic strips, Semenogelin

Urine confirmatory test

lateral flow immunochromatographic strips, Tamm-Horsfall protein

Principle of lateral flow immunochromatographic strips

3 antobodies
- Detection conjugate, binds target protein in sample has colour
- Capture antibody (test), binds another antigen on target protein and captures protein antibodycomplex formed, if positive
- Capture antibody (Control), detects excess conjugate antibody migrates up beyond test site.

Solublisation of stain

Extraction buffers - EDTA or Tris

DNA extraction

- Chelex, binds to polar cells leading to lysis, fast, simple and cheap. Degradation in long-term storage.
- Silica, after lysis added to eppendorf, high salt DNA binds to silica, buffer washs away proteins, DNA eluted with water.
- FTA cards, hole punched out.

AGE

- Size = distance migrated
- Quantity = Brightness
- Too much = haze staining above main band
- Too little = small bands lost

PCR

Method for DNA quantification. Sequence amplified to determine quantity of DNA.
(1) denaturation of the template into single strands; (2) annealing of primers to each original strand for new strand synthesis; and (3) extension of the new DNA strands from the primers.

prior to cell division DNA duplicated. DNA polymerase joins nucleotides forming new DNA strands. PCR mimics replication.

STR

DNA with repeat units 2-7bp length. Length and number of repeats vary.

Inhibition PCR

Causes interference and degrades sample. 3 categories, internal, substrates and other sources.

CE

- High voltage.
- Capillary with polymer solution, ends dipped in electroyte.
- Samples added and voltage on, DNA migrates to anode.
- Pass through window, fluorescence and migration time recorded, shown on electropherogram.

CE DNA

Size based. Temp 60C. Urea keeps DNA denatured.

PCR

Taq polymerase, emzyme that heat resistant.