27 June 2010

Who am I?

Who am I? - Philosophers asked this question for thousands of years! Though Darwin discovered the answer 150 years back, now we know the nuts and bolts of life! Life is nothing but certain intricate set of chemical processes working together and its fundamental process involves creating proteins (the building blocks of our body) from the amino acids (food) using a design template called genes (parts of DNA).

[Gene] + [Amino Acids] ---> [Protein]

A gene is a functional part of DNA which corresponds to our one or more physical or mental characteristics. It is represented as a sequence of 4 letters: A, C, G and T (each corresponds to 4 different sub-molecules of DNA). These genetic instructions could be modified or damaged by many environmental factors, for example DNA damage by UV light or smoking. Ultimately, the genes and the environment (includes food, habits, life-style and other internal/external environmental factors) determine who we are!

[Who am I?] = [My Genes] + [My Environment]

Now a days, people are started doing DNA analysis (like blood test) to understand their design makeup - their health , traits and history! DNA analysis can be simply done from our saliva sample, as every cell in our body carries our genetic materials.The picture below shows our nuclear DNA (Our genome consists of 22 pairs of chromosomes and XY chromosomes; chromosomes are the package for DNA) and mitochondrial DNA.
  • 1-22 pairs of chromosomes, one set is from mother and another set is from father.
  • X-chromosome is from mother and Y-chromosome is from father to son (XY determines male sex; for females, it will be XX).
  • MT is mitochondrial DNA. Mitochondria reside outside the nucleus of the cell, and it is not part of our genome. It is only passed from mother to children.
  • For each chromosome, the number of Bases, Genes, SNPs are specified. A Base can be one of A, C, G or T (An example for 10 Bases sequence: CAGGAATGCA. Likewise, the 1st chromosome has 247 Million Bases sequence). Different parts of this sequence form different Genes. SNP (single-nucleotide polymorphism; pronounced as snip) is a single Base variation in the genes. SNP-s are used to identify gene variations in the population.
  • Ultimately our genotype for each SNP is used to determine our specific characteristics as an individual. For example, a SNP from the 1st chromosome (with gene name, position in the sequence, SNP marker, possible versions in that position, and genotype):
[Gene] [Position] [SNP] [Versions] [Genotype]
SDF4 74242 rs3094991 A or G GG

(Note: Possible combination for A or G are AA, AG, GG, GA)

The following lists include some of the things we could know about design makeup.
  • The diseases that we have lower risk or higher risks, such as Diabetes, Rheumatoid Arthritis, Melanoma, Bipolar Disorder, Obsessive-Compulsive Disorder, Obesity, Heart Attack, Cancer, Parkinson's Disease...
  • Our sensitivity response to different drugs or treatment such as Interferon Beta Therapy, Warfarin Sensitivity...
  • Our level of susceptibility to alcohol dependence and Heroin addiction.
  • Our caffeine metabolize rate and related heart attack risk.
  • Our traits such as taste blind, color blind, eye color, hair color, earwax type, Lactose intolerance, muscle type that determines athletics ability, sensitivity to pain, longevity, odds for baldness...
  • Our blood type, HDL cholesterol levels and its make up.
  • Our verbal, non-verbal intelligence, episodic memory (short term memory), long term memory, ...

Our mitochondrial DNA is passed on from mother to children. From the mitochondrial DNA mutations (changes in the genotype) at different point in human history, our ancestry can be traced back to our African ancestors where humans first evolved (it can even be traced back further to our close relatives chimpanzee, gorilla, monkey, etc.). Likewise, our Y-chromosome is passed on from father to son. From the Y-chromosome mutations at different point in human history, our ancestry can be traced. Based on these mutations, groups known as haplogroups are defined.

Before 500 years ago, intercontinental travel is not easy. So, human migration from Africa to Europe, Asia, America and Australia can be traced along with the haplogroups.

The picture shows maternal line migration. For example, Haplogroup M (sub group of L3) (Populations: Indians, Chinese, Tibetans) is one of two branches on the mitochondrial DNA tree that arose about 60,000 years ago, soon after humans first expanded out of Africa. Because of its deep roots it is widespread in southern and eastern Asia, and its branches extend into North America as well.
This is just a beginning of what is possible in the future. Humans are the first species on earth to understand their own design makeup and can possibly transcend themselves into trans-humans!

"In the future...a new generation of artists will be writing genomes as fluently as Blake and Byron wrote verses" -- Freeman Dyson


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1 comment:

RajK said...

[Who am I?] = [My Genes] + [My Environment]. But this is not a simple linear equation. Often our genes determine our environment such as what kind of food we prefer, how much we might be addicted to many difference things, what kind of people we choose as our friends, etc. Likewise, our environment turns on or off certain genes, or damage or protect our genes. So, this is a highly intertwined tangled loop equation.

When we know our genes, we could change our environment (food, drugs, habits, etc.) in a way to maximize or minimize the effects our genes. This adds further entanglement to the already tangled loop equation.

Though it is useful for us to know the diseases that we might have high risk, it might fuel anxiety; but objective looking might help.