Biology Practice Questions

[cl24uw06]

I thought it would be helpful to start a link with biology practice questions. Here is the first one:

Which RNA typically contains the fewest nucleotides?
A. rRNA
B. tRNA
C. mRNA
D. All types of RNA contain the same number of nucleotides

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[userah]

I thought I'd add a FRAP question. Came across one I thought would be helpful to discuss

What is the % recovery and lateral mobility for large multi-subunit integral membrane protein that is not anchored to the cytoskeleton?

a. High % recovery with fast mobility
b. Low % recovery with fast mobility
c. High % recovery with slow mobility
d. Low % recovery with low mobility

The answer is not given but I'm pretty sure I got the reasoning right behind the one I think is the answer. Hopefully there are some other FRAP experts in here who can back me up when the time comes...

btw. if anyone that has taken the exam could just say whether the questions on this material were similar to how i phrased the question so I know if i prepared correctly for this question, that would be super. I know you're not allowed to post questions but is it 'legal' to "nod" at whether or not my question is similar to the ones on the actual dat? lol

alrighty, for this question, my answer is also C. Since it's not tethered to the cytoskeleton, lateral movement is possible thereby giving it high % recovery. However since it is a large multi-subunit protein, I can't imagine it traveling very fast thereby giving it slow mobility. Reasoning sounds simple enough. I'm going with Ockham's razor on this unless someone can prove me wrong haha

there is a hole in my theory however and it's one i hope someone can clarify. I wasn't positive on whether integral proteins are capable of movement. I tried searching for it on wiki but couldn't find anything of use. I'm sure peripheral proteins are capable of lateral movement but integral ones, not so sure of. Who wants to let me in on this little tidbit?

please and thaaaaank you

 

[AFF2009]

based on only my memory from intermediate cell bio class, Integral protein Indeed move laterally but limitations apply, unless the integral protien is anchored to a lipid of some sort from either side of the P.M. then thier movement would be restricted.

I could be wrong!

userah, thanks for all the contribuutions... I think your posts are very informative.

 

[TheWiredNerv]

alrighty, for this question, my answer is also C. Since it's not tethered to the cytoskeleton, lateral movement is possible thereby giving it high % recovery. However since it is a large multi-subunit protein, I can't imagine it traveling very fast thereby giving it slow mobility. Reasoning sounds simple enough. I'm going with Ockham's razor on this unless someone can prove me wrong haha

there is a hole in my theory however and it's one i hope someone can clarify. I wasn't positive on whether integral proteins are capable of movement. I tried searching for it on wiki but couldn't find anything of use. I'm sure peripheral proteins are capable of lateral movement but integral ones, not so sure of. Who wants to let me in on this little tidbit?

please and thaaaaank you

Integral membrane proteins can diffuse laterally.
I believe the answer to the question is A. If it isn't anchored it will easily diffuse to the portion of the membrane where it has been photobleached. Integral membrane proteins won't diffuse as rapidly as peripheral proteins but still fast. The answer is definitely A.

 

[AFF2009]

Integral membrane proteins can diffuse laterally.
I believe the answer to the question is A. If it isn't anchored it will easily diffuse to the portion of the membrane where it has been photobleached. Integral membrane proteins won't diffuse as rapidly as peripheral proteins but still fast. The answer is definitely A.

I see your point, but relative to a peripheral protein, wouldnt u think it would be slower?

 

[uesider]

I had the FRAP question last year. I had studied up on it using multiple websites, and still had no idea what they were asking... so my advice is, don't worry so much about this one question. It would of course be nice to get it right, but there is not even a guarantee it will even show up on your exam, and IMO your time is better spent studying topics that you will 100% see on the exam (plant bio, for example)...

Just a suggestion - don't get too worked up about one question - I seriously freaked out when I saw this question b/c there had been so much talk about it on SDN. If I had not heard so much about it and how it was going to be impossible, I wouldn't have worried so much and probably would have just picked an intelligent answer rather than having my brain race back to what people on SDN said! And was then all screwed up for the next few questions. My advice is just to do your own work and I'm sure you'll fare better than looking for answers on message boards. Good luck!

 

[TheWiredNerv]

I see your point, but relative to a peripheral protein, wouldnt u think it would be slower?

Yes, I said that in my post. However, it is still a rapid movement just not as rapid as a peripheral protein.

 

[AFF2009]

Yes, I said that in my post. However, it is still a rapid movement just not as rapid as a peripheral protein.

Hi there, I would REALLY Appreciate if you could please elaborate on your reasoning alittle more. Thank you


ALSO I had a question on the lymphatic system, so when the fluid in the interstial space is picked up by the lymphatic veins and filtered in the lymph nodes it will drain to .....what????

I read somewhere it drains to superior vena cava, and today I read in KAPLAN midterm soln that it drains to jugular vein. are they the same thing???/

Thanks

 

[TheWiredNerv]

I shall elaborate on my reasoning. When an area of the membrane is bleached in the technique, stuff in the membrane can laterally diffuse into that area. For proteins, if it is not anchored to the cytoskeleton, stuck in a really dense part of the membrane or stuck on other anchored components, it will laterally diffuse into the bleached areas. Both peripheral and integral membrane proteins that don't fall into any of the previous conditions will rapidly diffuse into the bleached part of the membrane. Just because it is a large subunit doesn't mean it will move slowly.

If you take a cell bio class and read through the scientific literature you will see that large integral membrane proteins can rapidly diffuse into photobleached areas of the membrane.

To be honest, I don't think anyone here should worry about FRAP more than the other bio topics that might be covered on the DAT.

 

[AFF2009]

I shall elaborate on my reasoning. When an area of the membrane is bleached in the technique, stuff in the membrane can laterally diffuse into that area. For proteins, if it is not anchored to the cytoskeleton, stuck in a really dense part of the membrane or stuck on other anchored components, it will laterally diffuse into the bleached areas. Both peripheral and integral membrane proteins that don't fall into any of the previous conditions will rapidly diffuse into the bleached part of the membrane. Just because it is a large subunit doesn't mean it will move slowly.

If you take a cell bio class and read through the scientific literature you will see that large integral membrane proteins can rapidly diffuse into photobleached areas of the membrane.

To be honest, I don't think anyone here should worry about FRAP more than the other bio topics that might be covered on the DAT.

Thanks for the elaboration...

quick question though if I were to tell u that the protein is normally not anchored anywhere and so since the integral and peripheral is irrelevant to their movement for the most part lets ignore that for now, ... If I were to tell u we genetically manipualate the expression and now it has anchorage to cytoskeleton or a lipid of some sort....

Now BOTH % recovery and speed of its movement would be reduced... is that correct?

 

[TheWiredNerv]

If it was anchored to the cytoskeleton it would be unable to diffuse at all.

 

[blueclue]

Here is my contribution.

The active site of an enzyme is determined to be hydrophobic and positively charged. A substrate that readily binds to the active site is more likely to be:

a. hydrophilic and positively charged.
b. hydrophilic and negatively charged.
c. hydrophobic and positively charged.
d. hydrophobic and negatively charged.

 

[AFF2009]

The active site of an enzyme is determined to be hydrophobic and positively charged. A substrate that readily binds to the active site is more likely to be:

a. hydrophilic and positively charged.
b. hydrophilic and negatively charged.
c. hydrophobic and positively charged.
d. hydrophobic and negatively charged

 

[LuckMC11]

bumpin this old thread seems pretty useful