How can I find the mRNA compliment of a DNA strand?

Question

I have a book with no explanation. For example.
What is the mRNA complement, from 5'-3', of the following DNA sequence?

5'-GATCCCGCTAAGGCCT-3'

Answer: 5'-aggccuuagcccauc-3'

This is the answer but my question is how come, I mean if DNA uses the opposite. Meaning there is Adenine, Guanine, Thymine and Uracil, why isn't the opposite of the first letter "Uracil" rather than the actual answer adenine? Can someone please explain this too me.

Answer 1

To get mRNA from DNA sequence:

Reverse the DNA = TCCGGAATCGCCCTAG
Convert into its complement = AGGCCTTAGCGGGATG
Substitue U for T = AGGCCUUAGCGGGAUG

When a DNA sequence is written as a single strand, it is ALWAYS the coding sequence that is given. When mRNA is made from the DNA, it makes the complement to this sequence --substituting U for T, as you already know. The trick is that the mRNA is transcribed in the 3' to 5' direction because it is temporarily bound to the DNA. Just like the complementary DNA would be written in the 3' to 5' direction, so is the RNA. In order to then write the mRNA sequence in the canonical 5' to 3' direction, the sequence needs to be written in reverse.

I hope that helps!

Answer 2

Mrna To Dna

Answer 3

Dna To Mrna

Answer 4

Synthesis of DNA and of RNA ALWAYS happens in 5'-3' direction. You have a filament which is written in 5'-3' and you need to transcribe it into mRNA with mRNA from 5' to 3'. In order to have 5' to 3' synthesis, you need to copy the template filament from its 3' to its 5' (Remember that 2 filaments are in the antiparallel conformation, where 5' is in contact with the 3' of the other filament and vice versa)

Answer 5

The above description is correct, but...

The answer is 5'-a because it matches the 3' end of the DNA that starts with t.

Answer 6

i think that's wrong. by my way of thinking:

if DNA is: 5' GATCCCGCTAAGGCCT 3'
then mRNA should be: 5' CUAGGGCGAUUCCGGA 3'

because then when translation occurs at the ribosome, the correct GAT CCC GTC... anti-codon will be bought to the mRNA strand....

Answer 7

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tgg cca ata i think this is right... i know that what you guessed is not correct tho because you can't pair an A with another A... you just have to find out what letter A goes with (and i think it's T) and then what C goes with (i believe G) and G goes with C, and T goes with A

Answer 8

Complemenarity:
DNA to DNA
A-->T
C-->G
G-->C
T-->A

In RNA uracil replaces thymine:
A-->u
C-->g
G-->c
T-->a

read from the 3' end.
T --> a
C --> g
and so on.