mRNA base sequences

Question help please!

Question:
Part of the DNA base sequence coding for a protein is shown below.
A T G G C C T A A G T G

State the corresponding base sequence of mRNA.

Answer:
U A C C G G A U U C A C

I though it would be AUGGCCUAAGUG, as I thought that the mRNA strand is built complementary to the template strand, which is complementary to the coding strand. So the coding strand should be the same as the mRNA strand.
Well I guess not... I think this is supposed to be an easy question too :frown:

Have I got my terms wrong somewhere? Why is the answer U A C C G G A U U C A C? Thanks!

Reply 1

Mel_1234

Template strand= the one that is used to make the mRNA
Coding strand=the one that is the same as the mRNA made.

The mRNA strand is made complementary to the template strand (by complementary base pairing), so, A T G G C C T A A G T G will form a mRNA strand with complementary bases,, A is complementary to T (which is U in mRNA), G is complementary to C.

So the mRNA will be U A C C T T A U U C A C.

I think i see where your getting confused, the question is indicating that that sequence is the template strand, when it says "coding for a protein" it isn't saying its the coding strand, stupidly worded question if you ask me. :frown:

(edited 11 years ago)

Reply 2

Kallisto

Entertainment Forum Helper

Its very easy to find the mRNA bases to the one of DNA. Notice that Adenine (A) is always complementary to Thymine (T), Cytosine (C) is always complementary to Guanine (G) and Adenine is always complementary to Uracil (U), but Uracil is just occur in RNA! That is to say whensoever DNA has Adenine as base RNA has Uracil as complementary base and not vice versa! Here are two examples:

DNA codon (which always consist of three bases): A G C
RNA codon: U C G

DNA strand: T G G A T C T A C
RNA strand: A C C U A G A U G

And now here is another DNA strand which can be completed by you!

DNA strand: G A T T A C C A G
RNA strand: ?

Reply 3

rocco94

I think you're confusing the fact mRNA consits of A, U, C, G - not T, U, C, G
A pairs with U
C pairs with G
and vice-versa

Reply 4

slacker07906

Adenine on a DNA stand is comlementary to Uracil on RNA strand.
Guanine is always complementary to cytosine.
Cytosine is always complementary to Guanine.
Thymine is always complementary to Adenine.

So on...

Get it now?

Reply 5

Kallisto

Entertainment Forum Helper

Original post by rocco94

I think you're confusing the fact mRNA consits of A, U, C, G - not T, U, C, G
A pairs with U
C pairs with G
and vice-versa

That's not quite right! Uracil is only a base of all kinds of RNA, but DNA has not an one. RNA may have Uracil as base, but DNA cannot!

A in DNA can be paired with U in RNA but, U in DNA cannot be paired with A in RNA, because U doesn't exist in DNA!

(edited 11 years ago)

Reply 6

rocco94

Original post by Kallisto

If you read my comment above you'll see that I said RNA has a uracil nucleotide, not DNA.

Reply 7

whotosee

Original post by Mel_1234

I think i see where your getting confused, the question is indicating that that sequence is the template strand, when it says "coding for a protein" it isn't saying its the coding strand, stupidly worded question if you ask me. :frown:

Ok thanks! That's the bit I was getting confused over :smile:

Reply 8

whotosee

Original post by Kallisto

Original post by rocco94

I think you're confusing the fact mRNA consits of A, U, C, G - not T, U, C, G
A pairs with U
C pairs with G
and vice-versa

Original post by slacker07906

Thanks guys, I know about the complementary coding stuff, I just got confused because I thought the DNA strand in the question was the actual coding DNA strand (as in part of a structural gene), not the template strand :smile:

Reply 9

Kallisto

Entertainment Forum Helper