DNA Profiling

Question 1

Describe the steps in DNA profiling

Answer 1

DNA profiling is the process of analysing DNA variations for the purpose of identifications → utilises DNA from an individual’s bodily tissues to identify suspects, victims and trace back lineage

1) Bodily material/tissue is collected (bodily fluids , mouth swabs, etc.) through swabbing, tape-lifting or direct excision

2) The DNA is extracted and copies are produced through PCR

3) DNA samples are put into wells in agarose gel

4) Gel electrophoresis separates DNA according to their size, as DNA moves through the pores in agar gel

5) Information is transferred to a southern blotting sheet

Note: DNA has a ‘net’ negative charge, positive electrodes at the end pull the negative DNA

Question 2

Outline how DNA profiling is used to determine parentage and identify victim identities

Answer 2

Suspects should be a complete match with the DNA sample taken from the crime scene if a conviction is to occur

Children inherit half their chromosomes from each parent and thus should possess a combination of parental fragments

Question 3

Define Short Tandem Repeats

Answer 3

Non-coding regions of DNA (introns) contain satellite DNA which is made up of repeating elements called Short Tandem Repeats

STR’s are what differentiates one individual’s DNA to another individual’s DNA

Question 4

Define alleles

Answer 4

An allele is one of two or more versions of DNA sequence (a single base or a segment of bases) at a given genomic location.

An individual inherits two alleles, one from each parent, for any given genomic location where such variation exists.

Question 5

Define homozygous and heterozygous

Answer 5

If the two alleles are the same, the individual is homozygous for that allele. If the alleles are different, the individual is heterozygous.