1. The diagram shows a molecule of an enzyme called ribonuclease. Each amino acid in the protein is indicated by a 3-letter symbol e.g. Arg = arginine. How many nucleotides are there in the mRNA molecule that codes for this enzyme? (1 mark)
2. The table below the mRNA code for the four amino acids in the part of the enzyme labelled X. Give the DNA code for the part of the enzyme labelled X (1 mark)
3 (i) Where does translation occur in a cell? (1 mark) (ii) Describe what happens during translation (3 marks)
4. Explain how the structure of DNA is related to its function. (6 marks)
That's incorrect. Transcription takes place in the nucleus but translation takes place within ribosomes typically outside the nucleus. Ribosomes in eukaryotes may be free floating or attached to the surface of the endoplasmic reticulum. In prokaryotes transcription and translation takes place more or less simultaneously due to the absence of a nuclear envelope.
*Sparkle*
Number two, I'm assuming that the part in the bracket is the bit labelled X. GGUUUAAGUGAG
Your answer is here is incorrect, but the most obvious one in my view is that it specifically asks for the DNA code - DNA does not contain uracil but thymine so all your bases are muddled. The answer I get is CGT AAT TCA CTC - which looks nothing at all like your bases. The codes you are given at the mRNA codes so you need to work out the complementary DNA code to the mRNA code you have been given.
The relationship between DNA structure and function is quite easy if you think about it. How is DNA copied? Why are complementary base pairings important to the structure and copying of DNA? Why is the double-helix important? Why is the DNA supercoiled? How is the DNA supercoiled? I'm not going to answer all those questions for you but those are the kind of answers you are seeking to break the question down for you a bit.
Number one is so easy that you shouldn't even have posted it. count.
Number two, I'm assuming that the part in the bracket is the bit labelled X. GGUUUAAGUGAG
You have given the sequence of the mRNA (although made an error in the 2nd nucleotide - should be C not U) ... however the question asks for the DNA sequence so you need to give the complementary sequence and change any U's to T's. Also strictly you should write out the sequence "backwards" as the convention is to write it out 5' to 3' which would be the reverse of the mRNA sequence due to the antiparallel nature of DNA.
Also, question 1 is a bad question. I assume they want you to count the amino acids and multiply by 3 to get the number of nucleotides. However this is not the number of nucleotides in the mRNA, as there are also sequences at either end which are not translated but are still present in the mRNA (such as the polyA tail at the 3' end).
the question asks for the "nucleotides in the mRNA that codes for the protein"
so you don't count the cap or the tail becuase these are removed from the sequence and do not code for amino acids in the protein...
That means how many nucleotides are there in the mRNA molecule itself. So you have "the mRNA molecule that codes for the protein" and it wants to know how many nucleotides are in that molecule.
If it wanted to know the number of nucleotides that actually code for the protein (ie excluding non-coding nucleotides) then it should say "nucleotides in the mRNA that code for the protein" ie code not codes because "nucleotides" is a plural word whereas the mRNA is singular!