itskimmy
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I have an exam coming up, and I'm going over the past exam paper. I'm stumped on DNA Sequencing, I just can't seem to understand it.

Reading text just doesn't go in, I learn best by being showed through simple step by step video tutorials but I can't seem to find any.

Past Exam Question

Answer the questions about the following antisense DNA sequence.

TAC TGA CCC CGA ATG

i. What is the sequence of the complementary strand of DNA?
ii. What would be the sequence of the mRNA transcribed from this
strand?
iii. Use the genetic code (provided in your data booklet) to determine the
amino acid sequence of the peptide coded by the sequence of DNA.

(2,2,5 marks)

Can anyone explain what is going on here, in really basic format. I have no idea what I would do if something like this came up in the exam.
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Eloades11
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(Original post by itskimmy)
I have an exam coming up, and I'm going over the past exam paper. I'm stumped on DNA Sequencing, I just can't seem to understand it.

Reading text just doesn't go in, I learn best by being showed through simple step by step video tutorials but I can't seem to find any.

Past Exam Question

Answer the questions about the following antisense DNA sequence.

TAC TGA CCC CGA ATG

i. What is the sequence of the complementary strand of DNA?
ii. What would be the sequence of the mRNA transcribed from this
strand?
iii. Use the genetic code (provided in your data booklet) to determine the
amino acid sequence of the peptide coded by the sequence of DNA.

(2,2,5 marks)

Can anyone explain what is going on here, in really basic format. I have no idea what I would do if something like this came up in the exam.
Ok, so I'm hoping you've covered DNA translation and transcription. The question has given you a DNA sequence, and also told you it's the antisense sequence. From this information you should be able to answer the first 2 questions. For the third one you simply need to look up the sequences in your data table and write down the corresponding amino acids.

If you get stuck, let me know and I'll help you.
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Just ZK
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To know the sequence of dna on the complementary strand you need to know the base pairing rule, i.e adenine always pairs with thymine and vice versa and guanine pairs with cytosine and viceversa. ( in short A-T,T-A, C-G, G-C.)
So to answer (i) the sequence would be
ATG ACT GGG GCT TAC
To answer (ii) u need to remember that in mRna adenine is replaced with Uracil instead of thymine so the sequence would be same as in (i) but u will replace T with U!
AUG ACU GGG GCU UAC
To answer ( iii) uneed a data booklet from which u would find the corresponding amino acids for the codons and u will be able to get 5 amino acids!
Hope that helped!
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