Episode 1: Primate chromosomes, from 48 to 46

I hope I've used all terms correctly, it's been a while since I've done any cytogenetics.

The question today comes from user "spylab" of Athens, Greece:
http://www.youtube.com/user/spylab/
"how did the transition from 48 chromosomes of primates to 46 of humans happen? I know that they fused but i cant understand the steps from 48 male 48 female to 46 m 46 f"
It's a great question for the first episode!

The short answer is probably a Robertsonian translocation. The frequency of these events in modern humans is about 1 in 1000 live births. You can start your own investigation into this phenomenon with reading the basics of translocations and the primate line chromosome fusion:

1. Robertsonian translocations:
http://en.wikipedia.org/wiki/Robertsonian_translocation

2. Ken Miller on the historical chromosome fusion event:
http://www.youtube.com/watch?v=zi8FfMBYCkk

3. Proc Natl Acad Sci U S A. 1991 Oct 15;88(20):9051-5.
Origin of human chromosome 2: an ancestral telomere-telomere fusion.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC52649/?tool=pubmed


4. Origins of primate chromosomes - as delineated by Zoo-FISH and alignments of human and mouse draft genome sequences.
Cytogenet Genome Res. 2005;108(1-3):122-38.
http://content.karger.com/produktedb/produkte.asp?DOI=80810&typ=pdfhttp:/...

5. We can reconstruct a number of chromosomal rearrangements that occurred much earlier in primate evolution:
Evolutionary descent of a human chromosome 6 neocentromere: a jump back to 17 million years ago.
Genome Res. 2009 May;19(5):778-84.
http://www.ncbi.nlm.nih.gov/pubmed/19411601

Category:

Education

Tags:

• c0nc0rdanceanswers
• Episode 1
• science
• biology
• cytogenetics
• chromosome
• fusion
• primates

[TheTomtompiper]

That Gene is gone ROLF!

[DNAunion]

In meiosis, crossing over does not "really" occur between sister chromatids; it occurs between non-sister chromatids of homologous chromosomes.

[PiratesVersusNinjas]

thanks!



[joebharris]

Why have I not subscribed to this yet?

[SinnFein4ever]

Subtitles, please.

[Theonewhoclimbs28]

"That gene's gone." I dunno why, but that was my favorite part.

[LucidCatnap]

Wasn't this going to be a weekly show? :(

[truckcompany]

This would of been a good House episode...

[AmunRaRocks]

Humans, the retards of the ape world.

[unassumption]

Am I the only one who heard Plato when you said Playdough?

I wasn't looking at the screen and had to glance up to make sure you weren't using bits of old dead philosopher to demonstrate crossing over ;P

[Craydon]

@RoScFan All we had to trade was the crazy raw strength of an ape... And lets face it, most people waste their potential.

[RoScFan]

@Craydon lamest? considering the non-mutant in this analogy are wild apes, a mutation to give them fucking super-intleigence is lame? if that happened to humans, we would probably get Xavier