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Multiple choice questions

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

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Multiple choice questions

Postby Luna » Thu Apr 03, 2008 9:32 am

mRNA binds oneself to the 30S ribosomal unit:
a) in a complex with GTP
a) first after it has been attached to initiating factors

Poly-a-tail:
a) Are in every eukaryote mRNA.
b) Exists if the transcript has a sequence which specify polyA on the 3’ end.

I didn't think it was in every single eykaryote mRNA, so I guess the b is correct

Stop codon:
Are recognized by equal terminating factors
Will always sit on the anti-codon bow.
Are recognize by own tRNA when these binds to the A seat
Are different in mitochondria’s and in cytoplasm.
Doesn’t exist in tRNA

Again I believe the answer is doesn't exist in rRNA, but I think I read somewhere that in mitochondrias one of the stopcodon actually codes for thryptofan?

Transcription factors binds to:
a. A intact DNA double helix, and promotes the binding of RNA Polymerase
b. Simple stranded DNA
c. Special seats where DNA helix has been melted
d. Histones

a or b?

A alfahelix is destabilized by:
a. Two Lys residues near amino terminus in alfa helix
b. Interactions between to hydrophobic Val residues in neighbouring positions.
c. Interactions between to Asp and Arg residues in neighbour positions.

Lys has a charge + while Val is 0, so I am thinking a

The advantage by measuring the initial reaction rate V0 at the beginning of the reaction is:
a. The [ES] is measured precisely
b. The changes in [S] are insignificant and [S] can be looked on as a constant
c. The changes in [Km] are insignificant and [Km] can be looked on as a constant.

Here I am a bit confused, maybe a or b.

E.coli DNA pol III:
a. Represents over 90% av DNA polymerase activity in E.coli?
b. Is the most important DNA polymerase in chromosomal DNA replication?

I think it's pol I that represents 90% and therefor I'll choose b

When a protein is completely hydrolyzed will the further analyse:
a. Only detect aminoacids in S conformation
b. Often detect other molecules besides aminoacids
c. Never detect more than 20 standard aminoacids
d. Never detect fewer than 20 standard aminoacids
e. Only detect the 20 standard aminoacids

This is a silly question because they don't mention what kind of protein where are looking on. Does anyone have some thoughts about this one?

Which of the following statements of E.coli RNA polymerase is wrong?
a. RNA made by this enzyme is complementary to the DNA template
b. The coreenzyme binds to the promoter, but will never initiate the synthesis without a sigma factor.

RNA will never be completyly complementary to the DNA because you change T with U.
Last edited by Luna on Sat Apr 05, 2008 12:29 pm, edited 2 times in total.
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Postby mith » Thu Apr 03, 2008 2:40 pm

Do you have a textbook? That would be very helpful.
Living one day at a time;
Enjoying one moment at a time;
Accepting hardships as the pathway to peace;
~Niebuhr
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Re: Multiple choice questions

Postby Luna » Sat Apr 05, 2008 12:25 pm

Yeah I have Campbell and Farrel biochemistry, but there are several answers that I can't fint. I think some of the answer are in Lehninger, but I don't have this book...
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