Question

Questions 9 to 13 are in reference to the DNA sequence shown in Question 8.

Here is Question 8.

Question 8:

The top strand of the following segment of DNA serves as the template strand:

3’ TACACCTTGGCGACGACT 5’

5’ ATGTGGAACCGCTGCTGA 3’

We will refer to this segment of DNA as the original (or unmutated) sequence.

Please answer the following questions:

(a) What is the mRNA sequence?

The mRNA sequence is  5'  3'.

**Please enter your sequence in the 5' to 3' direction. Deductions will be made if a sequence is inputted in the wrong direction.**

(b) Using the mRNA sequence you determined in part (a) of this question, give the sequence of the protein that would be translated.

The amino acid sequence for this protein is N-terminus  C-terminus.

**Please note**

The N-terminus refers to the beginning of the primary sequence for a protein, and the C-terminus refers to the end of the primary sequence for a protein.

i.e. input the amino acids in the order that they would be translated.

If a codon encodes for a stop codon, type STOP.

When inputting your sequence, separate each amino acid with a hyphen (e.g. Ser-Tyr-STOP).

You will need to consult the genetic code to answer this question.

Question 10:

The original (unmutated) DNA sequence (shown above in Question 8) has been mutated to the following (this represents the template strand):

3’ TACGACCTTGGCGACGACT 5’

We will refer to this sequence as mutation #2.

Please note that for simplicity only the template strand for this mutated segment of DNA is shown.

Answer the following questions:

(a) What is the complete mRNA sequence for the mutated segment mutation #2?

The mutated mRNA sequence is  5'  3'.

**Please enter your sequence in the 5' to 3' direction. Deductions will be made if a sequence is inputted in the wrong direction.**

(b) Using the mRNA sequence you determined in part (a) of this question, give the sequence of the protein that would be translated.

The amino acid sequence for this protein is N-terminus  C-terminus.

**Please note**

The N-terminus refers to the beginning of the primary sequence for a protein, and the C-terminus refers to the end of the primary sequence for a protein.

i.e. input the amino acids in the order that they would be translated.

If a codon encodes for a stop codon, type STOP.

When inputting your sequence, separate each amino acid with a hyphen (e.g. Ser-Tyr-STOP).

You will need to consult the genetic code to answer this question.

4 points   

QUESTION 11

Questions 9 to 13 are in reference to the DNA sequence shown in Question 8.

Question 11:

The original (unmutated) DNA sequence (shown above in Question 8) has been mutated to the following (this represents the template strand):

3’ TACACCTTAGCGACGACT 5’.

We will refer to this sequence as mutation #3.

Please note that for simplicity only the template strand for this mutated segment of DNA is shown.

Answer the following questions:

(a) What is the complete mRNA sequence for the mutated segment mutation #3?

The mutated mRNA sequence is  5'  3'.

**Please enter your sequence in the 5' to 3' direction. Deductions will be made if a sequence is inputted in the wrong direction.**

(b) Using the mRNA sequence you determined in part (a) of this question, give the sequence of the protein that would be translated.

The amino acid sequence for this protein is N-terminus  C-terminus.

**Please note**

The N-terminus refers to the beginning of the primary sequence for a protein, and the C-terminus refers to the end of the primary sequence for a protein.

i.e. input the amino acids in the order that they would be translated.

If a codon encodes for a stop codon, type STOP.

When inputting your sequence, separate each amino acid with a hyphen (e.g. Ser-Tyr-STOP).

You will need to consult the genetic code to answer this question.

4 points   

QUESTION 12

Questions 9 to 13 are in reference to the DNA sequence shown in Question 8.

Question 12:

(1 mark each)

In reference to the original sequence (shown in Question 8), classify each type of mutation present from Questions 9 to 11. Choose the best option for each.

mutation #1 mutation #2    mutation #3

A. base substitution - silent mutation B. insertion - frameshift mutation C. deletion - frameshift mutation D. base substitution - missense mutation E. base substitution - nonsense mutation

QUESTION 13

Questions 9 to 13 are in reference to the DNA sequence shown in Question 8.

Question 13:

Most mutations have a neutral effect on the phenotype, function or survival of an organism because they do not elicit any noticeable change. Whereas other mutations can have a positive effect on an organism leading to new versions of proteins that help an organism adapt to changes in its environment; while other mutations can have a negative effect on the organism and result in a protein that does not function normally or at all.

Answer the following questions based on the responses you gave above in Questions 8 to 12.

(a) Based on the protein sequences that were produced as a result of mutation #1, mutation #2, or mutation #3, describe the effect, if any, these mutations would likely have on the function of the protein within the cell. Support your answer.

(b) If these mutations occurred within a germline cell and not a somatic cell, how would the effects of these mutations differ?

Answer 1

The DNA sequence encoding the above 5 amino acids is included within the sequence below.

5’-AACCGAATTCCATGTTATAGC-3’ 3’-TTGGCTTAAGGTACAATATCG-5’

You isolate and sequence the following two different mutant alleles of Gene

Mutant 1 -

AACCAAATTCCATGTTATAGC-3’

Mutant 2 -

TTGGTTTAAGGTACAATATCG-5’

5’-AACCGTATTCCATGTTATAGC-3’ 3’-TTGGCATAAGGTACAATATCG-5’

Mutant 1 will not alter the folding of Protein A since this is an example of silent point mutation that does not alter the amino acid sequence of the protein.

Mutant 2 is an example of missense point mutation that changes the codon 5’AAU3’ (coding for asn106) to 5’UAU3’ (coding for tyr106) thus altering the folding of this protein.

You identify a disease of epidermal cells in mice in which Gene A is not transcribed. Further analyses reveals that the sequence of Gene A in affected and normal mice is the SAME.

Mature mRNA corresponding to Gene A lacks the 5 methyl Cap and 3’ Poly A tail

DNA around the promoter region of Gene A.