29 April, 2013

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

17 comments:

Alex J. Cavanaugh said...

We're limited - off course!

Pat Hatt said...

Humans were here before, knew it.

Old Kitty said...

I love that we are all related - our genes are of the same pool! :-)

Yay for May!!! I just really want a good summer now after such a wet and cold spring! Take care
x

Susan Gourley/Kelley said...

I'm ready for it to over. I have so much to do that I've been putting off.
I find genetic studies fascinating.

Robin said...

I agree with Susan - genetics are fascinating. Always thought it was the most interesting aspect of Biology Class when I was in school. I had no idea there was so much variation in the XX, XY possibilities. I was also unaware that sharing happened between X and Y, but not between X and X. It seems like it should be the other way around... hmmmm.

Maurice Mitchell said...

Genetic engineering isn't really my bag, but I will link to a pretty funny cartoon about the Y Chromosome.
http://popperfont.files.wordpress.com/2011/12/ychromosome.gif

Cindy Dwyer said...

I find it amazing what researchers can uncover.

DWei said...

The fact that we've managed to survive this long despite killing so many of each other.

Rob-bear said...

Most fascinating this about humans? That we have lived as long as we have, despite our self-destructive tendencies.

Blessings and Bear hugs!
Bears Noting
Life in the Urban Forest (my poetry blog)

Jeff Hargett said...

The Y chromosome means that half the population has their heads on straight. Which half is up for debate. :)

Holy Ghost Writer said...

Think there is more about human history then we will ever know

L. Diane Wolfe said...

I wonder where it came from then?

Paul Tobin said...

This has been an excellent challenge-well done

Sandy said...

So.........maybe those who being Gay is a choice don't understand the chromosomes? People here before, how does that track with biblical implications?

A-Z

nutschell said...

I've always found DNA and genetic studies fascinating. Love this post.
Nutschell
www.thewritingnut.com

The Golden Eagle said...

Alex: Well, you could look at it that way I guess . . . but it's the male chromosome that allowed scientists to track down human origins. :)

Pat: They've been around for a while!

Old Kitty: It's interesting how many differences there are within such a narrow genetic range.

Susan: Same here.

Robin: Actually, it is--XX chromosomes can swap genetic information and XY chromosomes cannot. I think I stated it that way in my post.

Maurice: LOL. I wonder what the female chromosome would look like put that way.

Cindy: I do, too.

DWei: That is a good point . . .

Rob-bear: Humanity sure does like to attack itself.

Jeff: LOL. I'd say it's split pretty equally. There are weirdos on all sides. :P

Holy Ghost Writer: Probably. Unless someone goes and invents time travel.

Diane: The original ancestor? Presumably from other ape-like lineages.

Paul: Thank you!

Sandy: Chromosomes don't really have anything to do with being gay, as I understand the science. Chromosomes determine gender/sex--not one's sexual orientation.

Nutschell: Glad you enjoyed it! :) Thanks for coming by.

Deniz Bevan said...

I wish I could get on that tv show where they trace your ancestors, like Eddie Izzard did. It would be so fascinating!