Question

Use the following DNA sequence as the template strand to answer these questions. (8 points)

5’- GAT CCT GCC TAA -3’

1. Draw the non-template DNA sequence, the mRNA sequence and the resulting peptide. Label the terminus of the DNA and peptide!!

2. Draw a point mutation. Is this a transition mutation or transverse mutation? Did it change the amino acid sequence(draw out the peptide)?

3. 4 bp insertion, and the resulting peptide.

4. 2 bp deletion, and the resulting peptide.

5. A copy number variant that contains 3 repeats of one amino acid.

6. A deaminated cytosine.

7. Do you think that this sequence would be affected by UV light damage? HINT: Consider this DNA as a double stranded DNA! Why or why not?

8. How many mRNA sequences can specify the amino acid sequence given by this DNA molecule? Write all the possible mRNAs that can code for the peptide- using only single nucleotide changes, you do not need to account for 2 base pair changes! Your answer will give you an idea about the # of possible mRNAs that can code for one polypeptide.

Answer 1

1.non template DNA sequence - 3' CTA GGA CGG ATT 5'

mRNA sequence- 5' GAU CCU GCC UAA 3'

peptide- asp-pro-ala

2. point mutation- replace A of GAT with T

it is transversion mutation as purine is replaced by pyreminidine

peptide- asp-pro-ala

no it didnt change the amino acid sequence

3. additon of AAAG after GAT

mRNA- 5' GAU AAA GCC UGC CUA A 3'

Peptide- asp-lys-ala-cys-leu

4. deletion of 2 bp i.e. CC

mRNA- 5' GAU UGC CUA A 3'

peptide- asp-cys-leu

5. deaminated cytosin is uracil

6. yes , sequence will be effected by UV as UV cause thymine dimer, cytosine dimer and even thymin-cytosin dimer which  can leads to mutation in DNA.

7. 6 possible mRNA sequence can be form from a DNA mol

5' GAT CCT GCC TAA 3'

3' CTA GGA CGG ATT 5'

mRNA 1 - 5' GAU CCU GCC UAA

mRNA 2 - 5' G AUC CUG CCU AA

mRNA 3- 5' GA UCC UGC CUA A

mRNA 4 - 5' UUA GGC AGG AUC

mRNA 5 - 5' U UAG GCA GGA UC

mRNA 6 - 5' UU AGG CAG GAU C

THANK YOU

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