<p>wait…
in the past some questions were about memorizing structures/properties of a.a’s?</p>
<p>omg…not fair.</p>
<p>Yeah…I remember on the semis last year, there was this question asking about which amino acid would fit best in the cell membrane or something and if you knew the properties of the amino acids, it would have been a piece of cake</p>
<p>I remember some questions about really weird chemicals on the 06 and 07 tests that I didn’t encounter again until I read orgo for the USNCO. Plus, there’s USUALLY enzyme kinetics on the USABO (at least for the past few years), and that’s usually worth 3 or 4 points. Since the 07 test I have always severely regretted forgetting all my chem, since those 3 or 4 points would have qualified me.</p>
<p>^wow…that sux…alot!</p>
<p>I think that we are allowed to discuss questions now. What did you guys put for the Nieuwkwoop center one?</p>
<p>C .
i always guess C :)</p>
<p>It was E. Nieuwkoop is found in what becomes the dorsal side of the embryo. That question as well as the SDS one required reading the expensive an detailed mol. bio book. Glad I bought and studied my copy, lol. Although the fact that they pulled out from that source…that requires studying that in conjunction with campbell’s for an entire summer + the school year leading up to the semifinal exam.</p>
<p>Does anyone else think the USABO semis is HARDER than the IBO theoretical? I’ve seen some of the IBO’s questions, and they’re somewhere in between open and semis in terms of difficulty.</p>
<p>hey guys, help me think of cheesy biology punchlines</p>
<p>Yeah, I think the USABO semifinal exam is harder than the IBO theoretical (for the questions I’ve seen), at the least for Part A. IBO is probably easier just because it tests more application than pure knowledge. Even though both tests have a lot of obscure knowledge questions, USABO seems to emphasize that more. On the downsize (or upside, if you’re lucky), however, IBO often makes all questions on one section (i.e., Animal physiology, genetics, plant physiology, etc.) focus on maybe only one or two corresponding chapters in Campbell book. If the animal section has most of its questions about embryonic development, and you only skimmed over that, then tough luck. On the contrary, USABO is usually a lot more even.
I don’t know about the difficulty of Part B on the IBO, though.</p>
<p>For the first two weeks of March, a brand-new copy of Molecular Biology of the Cell (the fourth edition) was selling for less than $40 on Amazon.com, since the fifth edition came out in January. I snatched it then.
The price has gone back up to around $70, unfortunately (retail $142). [Amazon.com:</a> Molecular Biology of the Cell, Fourth Edition: Bruce Alberts,Alexander Johnson,Julian Lewis,Martin Raff,Keith Roberts,Peter Walter: Books](<a href=“http://www.amazon.com/Molecular-Biology-Fourth-Bruce-Alberts/dp/0815332181/ref=pd_bbs_1?ie=UTF8&s=books&qid=1206576111&sr=8-1]Amazon.com:”>http://www.amazon.com/Molecular-Biology-Fourth-Bruce-Alberts/dp/0815332181/ref=pd_bbs_1?ie=UTF8&s=books&qid=1206576111&sr=8-1)</p>
<p>What’s a good approach to studying the book? Which chapters are the most necessary to read, and in what order should I read them? Reading every chapter (or even half the chapters) word by word like Campbell might be overkill.</p>
<p>I saw your name on AoPS; did you make semis this year?</p>
<p>I have no advice to give, really. I used Lodish’s book and just studied a chapter a day basically.</p>
<p>Which is better, Lodish or Alberts?</p>
<p>I skimmed Alberts pretty quickly at the beginning but only looked at a few pages of Lodish. No one in my school’s doing bio so I have no one’s opinion -_-</p>
<p>hey maybe i’m just really REALLY dumb or something, but i couldnt get that puc.16 cloning vector question! which restriction sites/enzymes were u supposed to use?? i couldnt get any of the sticky ends to match without breaking the ampR gene. also, my test was missing the sequence for the ORI restriction site, was anyone elses missing that as well?</p>
<p>@piccolo: Yes, I did, and I’m on AoPS.
@rustyjack: Couldn’t you still get an effective cloning vector even with a disrupted ampR gene? I thought I did. If you ran out of time, you could always resort to using probe hybridization. They’d probably just take off a few points for that.</p>
<p>Well, you had to write out each site’s complementary sequence. If you did, you saw that:</p>
<ol>
<li><p>The BamHI site was complementary to the EcoRI site.</p></li>
<li><p>The AluI site was complementary to the PvuII site.</p></li>
</ol>
<p>Cutting at these sites on the plasmid and the gene, and then adding the gene to the plasmid with ligase (I dont know if they’ll take off points for not going TOO in-depth such as describing the protocol for each individual action, I’d assume no because of the time limit) followed by transformation of plasmids into the bacteria (I didnt include this final step, so I probably lost 0.25 points for that), and that produced the proper recombinant plasmid.</p>
<p>Also…can RT-PCR be used for determining mRNA expression? Probably not, but I want to know from someone else (I circled microarray analysis as well as siRNA for that one)</p>
<p>How would they feel about blunt-end ligation with Klenow? This too would produce the recombinant plasmid.</p>
<p>I think RT-PCR should be a viable method, since it can amplify any amount of mRNA present, and you can always run blots to quantify that amount.
EDIT: Wait did the question ask for expression of mRNA? If this is the case, RT-PCR wouldn’t work haha…but if it was transcription that it measured…</p>
<p>I didn’t think of going that specific, but it sounds good to me.</p>
<p>Well, I just found this:
</p>
<p>Now I’m getting my hopes up that I was right lol.</p>
<p>i put microarray and rt-pcr for that one. why would siRNA help you determine gene expression?</p>
<p>From wiki:</p>
<p>
</p>
<p>
</p>
<p>
</p>
<p>It’s too late for me to analyze in-depth, but this is the argument for siRNA at least.</p>
<p>Yeah from my understanding siRNA is used to suppress mRNA expression by binding to it, thus preventing translation from occurring (as stated above). I just didn’t see how this allows you to measure gene expression. Maybe I’m wrong. I dunno.</p>