Home > Forensics > Basics of DNA Forensics Techniques

Basics of DNA Forensics Techniques

By: Ian Murnaghan BSc (hons), MSc - Updated: 15 Dec 2016 | comments*Discuss
 
Dna Techniques Successful Son Male

Obtaining DNA evidence is only a small part of the equation for proving a person's guilt or innocence. In fact, any forensics analysis - from criminal evidence to resolving paternity disputes - has DNA as a mere starting point. The true value lies in the outcome of DNA analysis, which can be performed through one or more of many different techniques.

Polymerase Chain Reaction (PCR) Analysis

PCR analysis is a technique that allows technicians to create millions of precise DNA replications from a single sample of DNA. In fact, DNA amplification alongside PCR can let forensic scientists perform DNA analysis on samples that are as tiny as only a couple of skin cells. In contrast to some other DNA analysis techniques, PCR analysis has the advantage of analysing minuscule sample sizes, even if they are degraded although they must not be contaminated with DNA from other sources during the collection, storage and transport of the sample.

Restriction Fragment Length Polymorphism (RFLP)

RFLP is a technique that is not widely used now but it was one of the first techniques used for DNA analysis in forensic science. Large sample sizes are needed for RFLP relative to newer techniques - usually a sample would need to be approximately the size of a one-pound coin. While that in itself may sound small, it is large relative to other techniques such as PCR analysis that require only a few cells for successful sequencing. In RFLP, the different lengths of DNA fragments are analysed. These fragments are from the digestion of a sample of DNA with a restriction endonuclease enzyme. The enzyme chops DNA in a certain style - the restriction endonuclease recognition site. Whether or not particular recognition sites are present will provide different lengths of DNA fragments, which are then divided up through electrophoresis. DNA probes then serve to hybridise the fragments through complementary binding.

Short Tandem Repeat (STR) Analysis

STR analysis works to examine individual areas in DNA. The differences from the collective areas of one person to another can allow for distinguishing between individuals. In criminal investigations, there are thirteen regions that are analysed and compared to establish profiles. In fact, DNA databases used at the government level involve the sequence of these thirteen regions. The chances of two people having the exact same thirteen regions is virtually impossible - likely one in a billion. A common DNA joke is that a person's odds of winning the lottery are higher than finding a perfect match for the thirteen regions.

Mitochondrial DNA Analysis

Mitochondrial DNA analysis works well on samples that are unable to be analysed through RFLP or STR analysis. There are two kinds of DNA in the cell - mitochondrial DNA and nuclear DNA. With other types of analysis, nuclear DNA is removed from the sample but with mitochondrial DNA analysis, DNA is removed from the cell's mitochondria. Sometimes, a sample can be old and will no longer have nuclear material in the cell, which poses a problem for the other types of DNA analysis. With mitochondrial DNA analysis, however, mitochondrial DNA can be removed, thus having important ramifications for cases that were not solved over many years. This means that mitochondrial DNA analysis can be very valuable in investigations for a missing person. Mitochondrial DNA will be the same from a woman to her daughter because it is passed on from the egg cell.

Y-Chromosome Analysis

Since the Y chromosome passes from a male to his son, analysing genetic markers on a Y chromosome can be of aid in identifying familial ties in males or for analysing any evidence entailing many males. Another benefit of Y-chromosome analysis is to establish a family line over many generations.

There are other types of analysis but these are some of the main traditional and current methods used to analyse DNA. No doubt, new techniques will be developed that will be even more rapid, successful and cost-effective.

You might also like...
Share Your Story, Join the Discussion or Seek Advice..
[Add a Comment]
What scientific knowledge would a forensic detective or scientist need?
BBKTHTSFINAL - 15-Dec-16 @ 8:35 PM
oooh, srry bb, im taken like Liam Neeson xD lol
trolleytram - 27-May-15 @ 8:30 PM
ive been on a new diet where I only eat cereal and stuff and its going well but I have a question, should I sh*t Post this much??? pls xplain tnks
trolleytram - 27-May-15 @ 8:24 PM
wow I never new pple could do that lol I wish I ws a doctor who could do all this lol xD
kat - 27-May-15 @ 8:19 PM
yeh that that's sounds fun man I will do that and I will have fun man! tnk sbut
goddog - 27-May-15 @ 8:17 PM
put the glass in a bucket and boil superglue in the bucket but make sure its upside down and then the prints will stay on! the bucket that is, not the glass. also don't breath in fumes It might kill you!
goody - 27-May-15 @ 8:14 PM
Can you do testing of DNA and finger prints for the public or for only the police? I live near Chester.Is there a CENTRE in Chester that I can take a book and a drinking glass to?I want to find out if the book and the drinking glass have the same finger prints. Also what is the best way to wrap a glass to keep finger prints as clear as possible?
Bibi - 9-Apr-11 @ 12:04 PM
Share Your Story, Join the Discussion or Seek Advice...
Title:
(never shown)
Firstname:
(never shown)
Surname:
(never shown)
Email:
(never shown)
Nickname:
(shown)
Comment:
Validate:
Enter word:
Topics
Latest Comments
  • ExploreDNA
    Re: DNA Test after Death
    Cat - Your Question:I was told that the man that I called Dad wasn't my father. The man that is supposed to be my father is die in 2012 but I…
    16 August 2017
  • Cat
    Re: DNA Test after Death
    I was told that the man that I called Dad wasn't my father. The man that is supposed to be my father is die in 2012 but I have some of his…
    14 August 2017
  • ExploreDNA
    Re: DNA Test after Death
    Rmebraatt - Your Question:My son passed away and I have his ashes and baby teeth, is there a way to get his DNA profile? I was adopted and…
    10 August 2017
  • Rmebraatt
    Re: DNA Test after Death
    My son passed away and I have his ashes and baby teeth, is there a way to get his DNA profile? I was adopted and told the search would be…
    9 August 2017
  • Freddy
    Re: DNA Test after Death
    My ex wife has always told me my late son was my biological son but o was not named on the birth certificate!!! My son also had a son 3mths…
    26 July 2017
  • ExploreDNA
    Re: DNA Test after Death
    Lost - Your Question:I have 3 older sisters who share the same mother and father. When I was conceived, my mother and her husband were…
    26 July 2017
  • Nothing
    Re: DNA Test after Death
    In Hindu purana their is a story once sage suklacharya drunk a water in which it contains burnt ashes of a dead body...in this mythical story…
    22 July 2017
  • Lost
    Re: DNA Test after Death
    I have 3 older sisters who share the same mother and father. When I was conceived, my mother and her husband were legally separated. My…
    21 July 2017
  • Liz
    Re: DNA Test after Death
    My daughter's grandma called to see if my daughter could go to mexico to give her DNA. She gave no reason why she needed. I can only guess…
    13 July 2017
  • ExploreDNA
    Re: DNA Test after Death
    Mari - Your Question:I want to know if I can do a DNA test on my son his father passed away disnt give him time change it in the birth…
    6 July 2017
Further Reading...
Our Most Popular...
Add to my Yahoo!
Add to Google
Stumble this
Add to Twitter
Add To Facebook
RSS feed
You should seek independent professional advice before acting upon any information on the ExploreDNA website. Please read our Disclaimer.