<p>Personally, I don’t think you need much besides Campbell and Raven’s even at Finals level. Alberts is good, but reading it is like trying to kill a mosquito with a canon. Those two can get you to Finals for sure (I just used Campbell). Once you get to camp, just try to take in what they tell you and get enough sleep and you’ll be fine. </p>
<p>boomvoom4000</p>
<p>Gee golly gosh glycophosphoric acid, anyone else of the opinion that CEE adores watching new schools register for USABO like rats scrabbling at the walls of their glass confinements? Cuz I sure am. I’ve tried to register for the last two years and CEE has flatly ignored my emails, calls, and faxes - all I get logging in is a big fat “YOUR SCHOOL HAS NOT BEEN APPROVED. CHECK BACK AGAIN IN 4 YEARS.”</p>
<p>Does anyone have a copy of the 2013/2014 open exams & answer keys for practice?</p>
<p>Could someone explain #3 on the 2012 Semi Exam to me? <a href=“http://www.greatneck.k12.ny.us/GNPS/SHS/dept/science/truglio/ap-webpage2011-12/usabo/2012-semifinal-exam-partAandB-questions.pdf”>http://www.greatneck.k12.ny.us/GNPS/SHS/dept/science/truglio/ap-webpage2011-12/usabo/2012-semifinal-exam-partAandB-questions.pdf</a></p>
<p>Does anyone have the 2014 USABO Open Exam?</p>
“The forces that hold different chains together are the same that hold the tertiary structure together, hydrogen bonding between polar R-groups, ionic bonds between charged R-groups, hydrophobic interactions between nonpolar R-groups, and disulfide bonds”-http://www.austincc.edu/emeyerth/tertiary.htm
Therefore, we can assume that disulfide bonds (s-s between cysteine amino acids) are holding the subunits together. Now what does this signify? To break the protein’s Quaternary structure, we would need to break polar R bonds, ionic bonds, nonpolar interactions and disulfide bonds. Now let us examine our question
You attempt to isolate two different subunits from a protein by running a
denaturing protein gel electrophoresis. To your dismay, you only find one band on
the gel that corresponds roughly to the total size of the protein. What did you most
likely forget to add?
A. an oxidizing agent
B. a reducing agent
C. loading dye
D. polyacrylamide
E. SDS, a detergent
Well, with electrophoresis, an oxidizing agent (takes in electrons) is normally not required. A… NO
B. a reducing agent can donate electrons to the disulfide bond (let us view each sulfide as two single bonds and two lone pairs. Each single bond has a single electron, and with two molecules, two electrons are shared between the two sulfurs. With two electrons added, the single bond would break into two lone pairs on each sulfur- (formal charge -1) and then a proton accept the lone pair, forming SH (known as coordinate covalent bonding) One can envision a scenario similar to hydrolysis, although in hydrolysis OH- acts as the lewis base and in this case, both S act as lewis bases).
Basically, the reducing agent can break disulfide bonds… and you can read my explanation above if you want.
C. Loading dye gives color. YES! this will contribute to the breakage of quaternary structure
(just as a side note, I’m being sarcastic. If you think loading dye is the correct answer… you have more problems than biology)
D. Polyacrylamide, like loading dye, is just a required component for all polyacrylamide electrophoresis. The equivalent of Steak in a steak meal. No steak? not a meal. Exactly, you would see nothing but a giant reflection of your face on the glass if you didn’t have polyacrylamide.
E. SDS. OK. This is actually tricky. You should know that SDS, as a detergent, does in fact denature the protein. However, it does NOT break covalent bonds. Rather, it acts through intermolecular forces, rather than intramolecular forces. The fact that the protein was able to denature, just not to separate subunits, attests to the fact that SDS may have been utilized. Further reading:http://www.pnas.org/content/106/6/1760/F5.expansion.html
WOW! I was really bored. If I’m wrong… well sorry! Good luck studying!