So you know that DNA is made of two, long intertwined threads which you associated with the names Watson and Crooke. Well, there is actually so much more to DNA that you can even imagine. It would take a person around 50 years, typing for 8 hours a day to get over letter of your genome transcribed onto paper. But let take a look at some other curious facts.
1 Identical twins have identical profiles but not fingerprints
We have always known that monozygotic twins (identical twins) are indistinguishable from each other. They are essentially two carbon copies both physically and genetically. Alas, even what has just been stated is not exactly correct. A study published in the American Journal of Human Genetics showed that identical twins do not in fact, have 100% identical DNA profiles. At school we invariably all learned about identical twins being genetic mirror images of each other – given this current discovery, we might as well “unlearn” this notion. The main distinguishing factor between a set of identical twins is their fingerprints – no two people in the world have the exact same fingerprints and it seems that no two people have the exact same DNA profile.
2 People can have more than 1 blood group
Yes, it is possible for the same person to have two blood groups and even two genetic profiles. These special people (or animals) are referred to as being chimerical. Chimeras are a type of twin. Do not however, begin to visualize two people. A chimera twin is just a single individual. What happens is that during conception, two fertilized eggs fuse together to form one individual. Each fertilized egg carries its own set of genetic material and when these two fuse together, the resulting single fertilized egg has two different copies of DNA. A blood test from a chimera twin could result in the twin having two different blood groups. Furthermore, the DNA in a hair sample may yield a different DNA profile to a DNA sample collected from a biopsy, as if these were two different individuals involved.
3 We have two types of DNA
Most of our genetic material and information is encoded in the DNA found in a cell organelle called the nucleus. The cell nucleus controls everything that goes on inside the cell. We do however have a different type of DNA found in a different part of the cell. The cell’s power station, known as the cell mitochondria, contains thousands of copies of mitochondrial DNA. Mitochondrial DNA is passed solely down the maternal line and two people with the same mother will have the exact same mitochondrial DNA.
4 A person cannot be identified by the DNA in their hair
Cut a hair or pick one up that has washed off you in the shower – do you think the DNA found in it can uniquely identify it as your hair? You are wrong if you think thus. The DNA in a cut or shed hair is only mitochondrial DNA. We have just explained that mitochondrial DNA is the same for all maternal blood relatives. In other words, your hair could from a genetic profile perspective, belong to any female relative. What the hair would need to have in order to uniquely identify it as your hair is the hair root.
5 We don’t all have the same number of chromosomes
We all learn the basics of human chromosomes which are as follows: we all have 23 pairs of chromosome which are XX in females and XY in males to give a total of 46 chromosomes. Well things could not be more different for some individuals. People with Down syndrome are characterized as having an extra chromosome, which means a total of 47 chromosomes. Klinefelter syndrome is a disorder in which males have an extra X chromosome (XXY) – sometimes they may have even two or three extra. Another condition which affects only females and is known as Turner’s syndrome, results from a missing chromosome. Instead of the female chromosome being represented as XX it is represented as X0.
6 Your DNA is far from unique
We all wish to be unique but our DNA is not what makes us so. In fact, only around 2% of your DNA is unique and the remaining 98% you probably share with any random person in the street, even perhaps with the person you dislike most. Moreover, you also share a lot of DNA with other animals, plants and microorganisms. Fruit flies for example, share around 60% of their genes with us. Chimps share around 98%. With mice, we share around 92%. Luckily, we only share about 18% with primitive, prokaryotic bacteria.
About the author: Caroline Hughes is an online writer specializing in writing about genetics. The author regularly contributes to many online blogs and websites delving into various, related topics including forensic testing, genetic sampling information about genetic illnesses and health tests. Many of the articles, resources and information written by the author can be found at: easyDNA Australia
