A To Z Challenge: Y Chromosome And Your Ancestors

Human telomere structure, via Wikimedia Commons, Public Domain image

Like "W", there are no corresponding scientific fields that begin with the letter "Y". Hence, I'm posting about another specific section of study (a repeat from last year, I'll admit).

The Y chromosome is one of two sex chromosomes and contains over 59 million DNA base pairs, constituting almost 2% of total DNA in human cells. Sex chromosomes determine gender, of course--in normal cases, everyone has a pair of chromosomes, either XX (female) or XY (male). Occasionally there are cases of 48,XXYY (an extra pair of XY), 47XYY (extra Y), and 46,XX (fetus is male despite having female chromosomes due to an abnormal exchange of DNA).

A recent development involving the Y chromosome is the discovery that the most recent common ancestor of the Y chromosome--of which all current male genes are descended from--is thought to have lived 338,000 years ago. This is significantly before the oldest dated human fossils. The Y chromosome can be tracked because of the way it's transmitted, since it doesn't exchange as much genetic material with other chromosomes. Female XX sex chromosomes swap information; male XY chromosomes cannot since X and Y are limited in their compatibility.

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Sources:
http://ghr.nlm.nih.gov/chromosome/Y
http://ghr.nlm.nih.gov/handbook/basics/chromosome
http://www.genetics.edu.au/Information/Genetics-Fact-Sheets/Genes-and-Chromosomes-FS1
http://www.sciencedaily.com/releases/2013/03/130305145821.htm

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I can't believe it's the penultimate day of the A to Z Challenge. Are you looking forward to the end of the month? Will you miss the Challenge?

And what fascinates you the most about human history?


-----The Golden Eagle

A To Z Challenge: Xenobiology And XNA

Xenobiology, also known as astrobiology and exobiology, is the study of alien life, including how life may have originated on Earth. It encompasses physics, astronomy, chemistry, geology, and biology. Technically, xenobiology has nothing to study other than Earth itself--planets are continually being discovered, but they're very far away. However, research into the history of development of life on this planet has begun to yield possibilities for how it may have formed on others.

A new development in the field of xenobiology is XNA. DNA is the fundamental building block of life on Earth, so messing with it is obviously an idea with some risks involved. XNA, a synthetic material that stands for xeno nucleic acids, could be an interesting solution toward designing new life and preventing damage to existing DNA. It can store information the same way DNA can, and has the potential for being the basis of new life--but if two organisms, one with DNA and the other XNA, interacted, they could come into contact without affecting the other's genetic material, acting as a so-called "genetic firewall".

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Sources:
http://www.xenology.info/Papers/Xenobiology.htm
http://www.redorbit.com/education/reference_library/space_1/space_sciences/2574862/xenobiology_exobiology/
http://education-portal.com/articles/Xenobiology_Education_Requirements_and_Career_Information.html
https://astrobiology.nasa.gov/exobiology/about/
https://astrobiology.nasa.gov/about-astrobiology/
http://www.universetoday.com/46851/exobiology/
http://www.chem.duke.edu/~jds/cruise_chem/Exobiology/
http://www.accessexcellence.org/WN/NM/miller.php
http://www.newscientist.com/article/dn9941-instant-expert-astrobiology.html
http://scienceblogs.com/oscillator/2010/04/07/xenobiology/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2909387/
http://io9.com/5903221/meet-xna-the-first-synthetic-dna-that-evolves-like-the-real-thing

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Would you be comfortable with synthetic organisms existing alongside natural ones? Do you think humanity will ever come into contact with alien life?


-----The Golden Eagle

A To Z Challenge: Karyology And Why Your Genes May Be Patented

Karyology is a field involving an organism's cell nucleus, particularly its chromosomes. It is a branch of cytology--the study of cell function and structure--which is in turn a branch of biology. Technically the word karyology refers only to the physical presence of the nucleus and its components, excluding the study of how chromosomes control in different parts of the body.

Chromosomes are tightly wound coils of DNA. As you've no doubt heard or read, DNA is the fundamental building block of life on Earth; it is the instruction manual that tells organisms how to grow, survive, and reproduce.

My next point is not strictly a scientific development, per se, but I thought it was an interesting (and perhaps alarming) recent event related to the field. This April, on the 15th, the US Supreme Court will hear a case about patenting genes. Myriad Genetics discovered genetic mutations on BCRA 1 and BCRA 2 genes--mutations related to breast and ovarian cancer--in the 1990s and filed for a patent on DNA with those mutated sequences. They got the patent.

The upcoming argument in the Supreme Court is over the functionality of the DNA. The DNA Myriad Genetics patented is, officially, "isolated DNA", which means it has to be a single piece of genetic material outside the rest of the chromosome for it to fall under the patent. The Supreme Court will decide whether the DNA is functionally different from that in the human body--there is a "products of nature" doctrine which states that something with no "marked difference" to something naturally occurring cannot be patented.

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Sources:
http://www.thefreedictionary.com/karyology
http://www.thefreedictionary.com/cytology
http://stalikez.info/fsm/semp/site/caryo_gb.php
http://www.news-medical.net/health/What-is-a-Chromosome.aspx
http://www.genome.gov/Glossary/index.cfm?id=33
http://www.sciencedaily.com/releases/2013/04/130412084225.htm
http://www.slate.com/articles/news_and_politics/jurisprudence/2013/04/are_your_genes_patented_the_supreme_court_will_decide_if_they_can_be.html

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Do you think genes should be patented? Or do you think patent offices should not allow specific DNA sequences to be "owned" by companies?


-----The Golden Eagle