September 23, 2020, 05:42:47 PM
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Topic: Can someone explain some of these answers from my study guide?  (Read 489 times)

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Offline yourdeath01

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Went through a 40 question study guide from my biochem class, picked out some of the questions that were confusing me. All the answers are picked already from the answer key so every answer is 100% correct. Feel free to chime in on any of the questions you are familiar with!

* https://imgur.com/PIetQNF

I literally have no clue what this means. I know that Trypsin protase cuts after R or T while Chymotrypsin cuts after F,W,Y but I'm not sure if this question is related...

* https://imgur.com/aJdT4Cs

Also don't understand this question (31 included) as well, I thought maybe the answer would be A cos it starts with Glycine which has small R group so it would bind tight but I don't get the question anyways

* https://imgur.com/lp8GlVz

phi and psi angles are just torsion angles for allowed conformations for the amino acids but nothing to do with alpha carbon-carbon so A is wrong?

I think 100% of phi and psi needs to be known not 10% so B is wrong?

Also torsion angles are just the allowed conformations for aminos and they don't expand downstream angles so that's wrong too.

Ramachandra plot actually just shows the possible angles in which amino acids are allowed in nothing about overcome.

Did I get all these correct so answer is E?

* https://imgur.com/SNXs4k3

In my class we only went over phosphorylation and glycosylation so I'm not sure if their is a quick way for me to learn the other 3 (methylation, ubiquitination, lipidation) but any tips to understand this?

* https://imgur.com/8ZQlblK

A would be wrong cos covalent bonds, h bonds, alpha helices, beta sheets all come together not just primarily covalent bonds.

B has nothing about protein folding so that's obvious wrong

I thought C would be the right answer here, what is C missing that would make it correct?

I don't know what option D even means... I mean when we are a folded protein we have low entropy cos of a more organised system but I'm not sure if a folded protein has anything to do with energy

Offline Babcock_Hall

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Re: Can someone explain some of these answers from my study guide?
« Reply #1 on: April 07, 2020, 09:29:37 AM »
With respect to the first image, b-ions and y-ions both result from the breakage of a peptide bond in mass spectrometry, but they differ in which atom is positively charged.

With respect to the second question in the second image (Q31), I would look at the type of atom or functional group being modified in each PTM.  Same for image 4.

With respect to the third image you wrote, "phi and psi angles are just torsion angles for allowed conformations for the amino acids but nothing to do with alpha carbon-carbon so A is wrong?"  Phi and psi are both torsion angles around the alpha-carbon (so what you wrote is not correct); however, both kinds of torsion angles involve the positions of 4 atoms.  I think that your reasoning is OK for the rest of the question.

For D in the last image, what is your conclusion with respect to the Anfinson experiment with ribonuclease A?  For C, can you describe which atoms participate in the hydrogen bonding in an alpha-helix or a beta-sheet?  For B your reasoning is wrong.  The folded structure of ribonuclease A has disulfide bonds, and so do some other proteins (not all, however).  For A, your answer would be more focused if you discussed only noncovalent forces.  An alpha-helix is not a force; it is a structure that results from certain forces.




Offline yourdeath01

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Re: Can someone explain some of these answers from my study guide?
« Reply #2 on: April 07, 2020, 02:39:10 PM »
thanks

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