<p>Put question.
Someone attempt to answer. Blah blah</p>
<p>My question is how to calculate the molecules of double stranded DNA present? (Number 5 in ER) :X</p>
<p>in for later</p>
<p>Wow I just took multiple choice of summer 2009 and bombed.</p>
<p>I was just looking over some summer 09 questions. and i realized how much i needed to review the first few labs. argh</p>
<p>hey batman, type the question out for us</p>
<p>double recombinants - are they discussed in the lab manual? i can’t find them there</p>
<p>is it just crossing over two times? why is the chance of this very unlikely?</p>
<p>i coulda sworn i never heard mike meighan lecture about this…</p>
<p>i don’t even know where to begin asking questions. i’m so screwed for this test.</p>
<p>hey we still have 4-5 days, and we already know some stuff just from being in lab lol</p>
<p>that’s the way i look at it at least =/</p>
<p>Basically when cross over occurs twice for example </p>
<p>a b c -----> a b+ c
a+ b+ c+ -----> a+ b c+ (twice as “a” and “b” crossed and so did “b” and “c”)</p>
<p>The chance of this happening is very unlikely because one recombination is already very rare so 2 recombinations is just over kill and extremely unlikely. </p>
<p>Remember in statistic probably is in decimal so for example cross over one is .2 and cross over two would be like .1 so overall probability is (.2*.1) = .02 (way small and unlikely)</p>
<p>and double recombinance only occurs when the a, b, c alleles are all genetically linked together? could double recombinance occur if two of the alleles were physically linked but not genetically linked?</p>
<p>i.e.</p>
<h1>a-b---------c</h1>
<p>a-b---------c</p>
<p>where a and c are so far apart that they’re not genetically linked</p>
<p>sorry, had to use dashes because the forum doesn’t let me make a lot of spaces…</p>
<p>can someone explain to me summer 2009 number 22? A scientist takes nuclei of 10 sperm cells, which are genetically identical. Then he heats and denatures, breaking H bonds but not covalent. What statement best describes the denatured dna?
230 total, rep 23 unique DNA seq, 230 tot, rep 46, 460 total, rep 92. 460 total rep 46, 920 tot, rep 92 uniq.</p>
<p>I just cant wrap my head around this quesiton.</p>
<p>23 chromosomes in each sperm cell
10*23 = 230 total chromosomes
1 chromosome = 2 strands of DNA</p>
<p>so we have 460 strands of DNA
each of those 460 strands has a unique DNA sequence</p>
<p>so D</p>
<p>edit:</p>
<p>wow these questions are ****ing hard lol</p>
<p>Ya I actually figured it out a few minutes after. I couldn’t get my brain to think that dna would be 460 strands because of denature. damn it.</p>
<p>the denature part was just to trick us right? lol</p>
<p>perhaps. i was thinking that denature would mean like splitting the dna into two thereby making 460, though that’s probably not the best way to think about it.</p>
<p>Hey, how do I do restriction maps and such? I’m so lost.</p>
<p>im still watching lecture 5… i have yet to learn genetics yet… oh man.</p>
<p>Page 39 of Lab reader, #9</p>
<p>I don’t understand why we don’t have to multiply the supposed correct answer (D) by 2. Shouldn’t we have to because there are twice as many chromosomes present in the kidney cells as there is a sperm cell?</p>
<p>You already did multiply by two right? there’s only 14 chromosomes in the sperm cell (n=14). So the kidney would be 2n = 28. Yeah? Or am I just doing it wrong lol</p>
<p>well i’m talking about the base pair part</p>
<p>i think it should be the answer in D but multiplied by 2, i don’t understand why they didn’t multiply by 2</p>