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Are these right?--won't take long..

Discussion of all aspects of biological molecules, biochemical processes and laboratory procedures in the field.

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Are these right?--won't take long..

Postby biology_06er » Sat Nov 03, 2007 4:16 am

Had an exam yesterday and would just like to know if I am right in a few MCQs...I have just written out the ones I chose:

affinity chromatography is a purification technique that:
separates proteins according to size
explots an unique property of a protein
separates proteins according to their hydrophilicity
involves ion-exchange chromatography
results in protein samples that are denatured

cellulose acetate electrophoresis indicates that albumin:
is -vely charged
is +vely charged
is a minor component of serum
is a basic protein
has a PI close to the ph of the electrophoresis buffer

the rate of enzyme catalyzed rxns is usually determined by measuring the initial rate of rxns because:
only the initial rate is simply related to the initial substrate concentration
enzyme rxns are always fast
at equlibrium the absorption of light will continue to increase
otherwise the light absorption will go off the scale
the initial rate is always the slowest

Papain incubated with EDTA:
Activates enzyme activity by binding divalent metal cationshave no effect on enzyme activty
activate enzyme activty by modifying the casein substrate
inhibit enzyme activty by binding divalent metal cations
inhibit enzyme activty by binding divalent metal cations

When acid is added to the rxn: ethanol + Nad+ <--> acetaldehyde + NADH + H+ the following is expected to happen:
Increases the conc. of NADH

interaction between cibacron blue and albumin is considered:
Hydrophobic

when the liver enzyme alcohol dehydrogenase oxidizes ethanol an increase in the absorbance of the solution occurs at 340nm. This is because:
NADH is produced during the rxn

In the lab where the enzyme papain is investigated, it was preincubated prior to assay to:
ensure that the reactive site cysteine was in the reduced form

I know there is heaps of q's but any1 that can tell me if they are wrong/right will be great...I just wanna make sure I have got the marks for these so having the ans. to this post will be MOST appreciated!!

Thanks you to whoever answers!!
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Postby MichaelXY » Sat Nov 03, 2007 4:25 am

You have a good memory, I can never remember questions in that detail after a test.
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Postby biology_06er » Sat Nov 03, 2007 10:03 am

haha i wish i had a good memory then I would do better on exams!...we actually get to take the paper home :P
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Re: Are these right?--won't take long..

Postby MrMistery » Sat Nov 03, 2007 3:57 pm

biology_06er wrote:Had an exam yesterday and would just like to know if I am right in a few MCQs...I have just written out the ones I chose:

affinity chromatography is a purification technique that:
separates proteins according to size
explots an unique property of a protein
separates proteins according to their hydrophilicity
involves ion-exchange chromatography
results in protein samples that are denatured


The correct answer is "explots an unique property of a protein". The technique used to separate according to size is gel filtration chromatography.

apain incubated with EDTA:
Activates enzyme activity by binding divalent metal cationshave no effect on enzyme activty
activate enzyme activty by modifying the casein substrate
inhibit enzyme activty by binding divalent metal cations
inhibit enzyme activty by binding divalent metal cations

EDTA binds metal ions through amine and carboxyl groups. However, i don't think papain has metal prosthetic groups. You can look that up and you will have your answer.

When acid is added to the rxn: ethanol + Nad+ <--> acetaldehyde + NADH + H+ the following is expected to happen:
Increases the conc. of NADH

My guess is it would increase the rate of the backwards reaction, as the added H+ will increase the concentration of products.

Don't know the answers to the others, or i consider your answers correct.

Cheers.
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter
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