PCR yield

Jeff Kramer jeff at COMPBIO2.MED.WAYNE.EDU
Thu Dec 15 19:46:58 EST 1994


Hello all.

	I have a PCR question for you(s).  A bit of my Central PA heritage 
coming out there in that "yous."  Any way, I am relatively new to PCR, so I am
at a loss for experience regarding my question.  I have been doing PCR on
total genomic DNA lately, and was trying to calculate s % yield.  Now I start
with 2.4 ng of jeff kramer genomic DNA, and I'm amplifying a 500 bp segment.
so 2.4 EE-9 * 500/6 EE9 (thats the number of bp in the human genome, so I've
been told) * 2^30 (2 raised to the 30th power, I'm doing thirty cycles) gives
me a theoretical (sp?) yield of .214 ug.  Well I'm regularly getting ~ 0.02 ug,
which is less than a 10% yield.  Now I realize that even a 95% yield at each 
cycle would end up giving me a pretty crummy yield after 30 cycles (Actually I
should probably do that calculation, eh?), but has any one else ever done such
a calculation?  And if you have, do you find a similarly "poor" yield at the
end of it all?  I can see my product on a gel, so thats really all that matters
and this is purely informational, but I was mighty vexed by this question all
day.
	I had to wait until tonight to write in, because every time I sit down
at the computer during the day, my boss thinks I'm not working.  I guess I'm
really not working right now, am I...
								Jeff



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