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Title: GENETICS MOLARITY QUESTION Post by: Valentine10 on Nov 4, 2010 'What is the molarity of a 50 microgram per mL solution of transfer RNA? [NB tRNA molecules are roughly 80 nucleotides long and the average relative molecular mass of a nucleotide subunit is 320] Give answer to 3 significant figures and in scientific notation.'
My first thought was to multiply 80 by 320(=25600) and that would be the mass of one tRNA molecule and then possibly convert that to micrograms.... then no idea I'm not really sure how to do this question at all. Help would be greatly appreciated :) Title: Re: GENETICS MOLARITY QUESTION Post by: duddy on Nov 4, 2010 80 * 320 would give you the molecular mass of tRNA molecule (You're right = 25600). Molarity is typically in the unit mol/L of simply (M). So they presumably want your answer in mol/L
molar mass (g/mol) = molecular mass * ((1/6.022)*10-23g/u)*(6.022*1023/mol) 50 ug / mL --> convert to g/L --> than divide this number by the molar mass you get from the above equation. I think that's how you do it, but I'm not totally sure. Title: Re: GENETICS MOLARITY QUESTION Post by: Valentine10 on Nov 4, 2010 I'm not really following your answer sorry.
When I did your calculation I got an answer of 1.95e-6. I don't really think that would be correct for the molarity, but then again I don't really know. Why did I have to convert the ug/mL to g/L? ??? Title: Re: GENETICS MOLARITY QUESTION Post by: Valentine10 on Nov 4, 2010 Im definately not getting this right at all by using this method. Can anyone please help me!?
Title: Re: GENETICS MOLARITY QUESTION Post by: bio_man on Nov 4, 2010 Yeh, I'm not too sure, I did what duddy said also and I got the same answer. It does make sense though, see the attachment.
Title: Re: GENETICS MOLARITY QUESTION Post by: Valentine10 on Nov 5, 2010 Ok thanks.
Title: Re: GENETICS MOLARITY QUESTION Post by: bio_man on Nov 5, 2010 Did you end up getting the right answer? I'd love to know if what we got was correct for future reference :-[
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