Part III Question 6

Part III Question 6

Every kingdom is bound to have its great ruler. For all our cells, we look up to the majestic power of DNA. On a general scale, we understand that DNA contains the instructive signals for protein formation. These proteins essentially determine our physical characteristics and play a vital role in keeping the normal functions of a human body (i.e. hormones, enzymes….).

Is he my dad? Are they my real parents? Do I have any siblings? Was he there at the crime scene? Who are the faces that once covered these bony skeletons?

Yes that’s right! The role of DNA isn’t limited to just creating proteins, it too, however, solves mysteries through DNA profiling. With the advancement of technology, forensic scientists are fortunate, as ‘DNA profiling’ has made it stand in the world today.

Figure 1.1 Broad application of DNA profiling

(Extracted from biocyclopedia based on Chawla, 1998) 

DNA profiling or more commonly known as DNA fingerprinting is a test to identify and evaluate genetic information- DNA.

Figure 1.2 depicts the steps involved in creating a DNA profile via the RFLP (Restriction Fragments Length Polymorphism) method.

Figure 1.2 Steps in creating a DNA profile.

(Extracted from How Stuff Works, http://science.howstuffworks.com/dna-profiling1.htm )

So, my dear budding detecteeth, after having a better understanding on DNA profiling, let us now put on our detecteeth caps and return to the murder case!

According to our resources, DNA profile showed evidence of a father and son.

How can we go about confirming this statement? 

What we have:

1. Skeletal remains

2. Files of possible victims

     - Herman Hartono

     -Adi Hartono

     -Anya Suriati

 Steps taken by detecteeth :- 

1) DNA profiles of Herman and Adi Hartono

DNA profiles for Herman Hartono and Adi Hartono are prepared from DNA samples such as hair, skin, semen or even blood samples kept by their family doctor. Authorities most probably had collected these DNA samples as evidence at the time of their disappearance and kept these records safe in their respective case files.

2) Extract DNA samples from bony remains found at crime scene

New sets of DNA profiles are prepared from the DNA samples extracted from these skeletal remains found at the crime scene.

3) Identify the victims

Compare the DNA profiles of the possible victims to the DNA profile generated from the bony skeletal remains at the crime scene.

Identify Herman and Adi Hartono respectively.

Figure 1.3 Identifying Herman and Adi Hartono 

(Prepared by Kavitta. T)

 4) DNA paternity testing

Here comes the fun part! We are about to enlighten ourselves as to whether Herman and Adi Hartono are biological father and son. To do so, we will be comparing 3 DNA profiles: Adi (son), Herman (father), and Mrs. Hartono’s (mother) DNA.

Figure 1.4 DNA paternity testing

(Prepared by Kavitta. T) 

Look at these three DNA profiles carefully, noticed that a good amount of DNA bands from Adi’s match those of Herman’s and Mrs. Hartono? Since a high percentage of Adi’s DNA bands actually match those of Herman’s and Mrs. Hartono’s, we can conclude that Herman and Adi are indeed biological father and son.

(Note: Green coloured DNA bands showing genetic variation, which is a main feature of meiosis)

References:

http://science.howstuffworks.com/dna-profiling1.htm
http://www.webmd.com/a-to-z-guides/dna-fingerprinting

http://genetics.thetech.org/ask/ask20

The Mystery Behind Twin Formation

Statistically speaking, 2% of all pregnancies result in twins, where the majority 70% is fraternal twins and the remaining 30% being identical twins. 

The main difference between identical and fraternal twins is that:-

For identical twins, the earlier the embryo splits, the more independently the twins develop in the uterus. The etiology of the splitting of embryo still remains unknown.

For fraternal twins, it is due to hyperovulation by the mother. Hence, it is directly influenced by the mother's genes

Do Identical Twins Have The Exact Same Genes

Yes! As they arise from the same fertilised egg cell. however, there are subtle differences. These differences can be a result of mutations such as Single Nucleotide Polymorphisms (SNP) that may occur before or after the blastocyst splits into 2. Moreover, identical twins have different fingerprints too, because fingerprints are formed when a foetus touches the amniotic sac during the first trimester, forming "friction ridges" which are the precursor of fingerprints.

How Will DNA Profiling Help To Trace Anya To Tanya

DNA profiling is a banding pattern of genetic profiles produced by electrophoresis of treated samples of DNA. In Anya's case, DNA was extracted from the bone remains and is compared to the DNA of Tanya, which is extracted from the same tissue. This method used to produce DNA profiles is gel electrophoresis. If the banding pattern is the same, then it is a solid evidence that Anya is the victim of the case!

Reference: 

http://www.pennmedicine.org/encyclopedia/em_DisplayAnimation.aspx?gcid=000058&ptid=17

http://www.telegraph.co.uk/science/science-news/10511087/Identical-twins-need-never-be-tried-for-same-crime-after-DNA-breakthrough.html

http://scienceline.ucsb.edu/getkey.php?key=244