1. There are 6 scenarios given below, SORT the scenarios into TWO DIFFERENT grou

ID: 189162 • Letter: 1

Question

1. There are 6 scenarios given below, SORT the scenarios into TWO DIFFERENT groups. (Each scenario should be sorted into one and only one group).

2. Explain what scenarios in GROUP 1 have in common and what scenarious in GROUP 2 have in common.

3. Explain how the scenarios of group 1 differ the scenarios to group 2.

Scenario 1 Scenario 2 Some parts of unicorns can make wishes come true. The gene that encodes for proteins involved in making wishes come true, the WSH gene, has silencers and enhancers in its distal control region Some parts of trolls can make wishes come true The gene that encodes for proteins involved in making wishes come true, the WSH gene, has silencers and enhancers in its distal control region Unicorn WSH Region Unicorn WSH Region Element A Element B Element C Gene Element A Element B Element C Gene Distal Control Region Distal Control Region In unicorn tail tissue, transcription factor A is present and WSH is expressed In troll hoof tissue, transcription factor B is present and WSH is not expressed Scenario 3 Scenario 4 Some parts of unicorns can make wishes come true. The gene that encodes for proteins involved in making wishes come true, the WSH gene, has silencers and enhancers in its distal control region Some parts of trolls can make wishes come true The gene that encodes for proteins involved in making wishes come true, the WSH gene, has silencers and enhancers in its distal control region Unicorn WSH Region Unicorn WSH Region Element A Element B Element C Gene Element A Element B Element C Gene Distal Control Region Distal Control Region In unicorn horn tissue, transcription factor C is present and WSH is expressed In troll tail tissue, transcription factor A is present and WSH is expressed Scenario 5 Scenario 6 Some parts of unicorns can make wishes come true The gene that encodes for proteins involved in making wishes come true, the WSH gene, has silencers and enhancers in its distal control region Some parts of trolls can make wishes come true. The gene that encodes for proteins involved in making wishes come true, the WSH gene, has silencers and enhancers in its distal control region Unicorn WSH Region Troll WSH Region Element A ElementB Element C Gene Element A Element B Element C Gene Distal Control Region Distal Control Region In unicorn hoof tissue, transcription factor B is present and WSH is not expressed In troll horn tissue, transcription factor C is present and WSH is expressed

Explanation / Answer

1. Sorting

Group 1: WSH is expressed

Group 2: WSH is not expressed

Scenario 1

Scenario 2

Scenario 3

Scenario 5

Scenario 4

Scenario 6

The scenarios are sorted based on whether the WSH gene is expressed in the unicorn tissues or not. The WSH gene has regulatory elements in its distal region that is controlled by three transcription factors: A, B and C. Depending on the expression of these regulatory elements, the gene will be expressed or not.

2. Group 1 scenario: Presence of transcription factor A and C will activate the expression of WSH gene. Hence, transcription factors A and C (TF A and TF C) are activators that bind the enhancer elements A and C respectively in the distal control region. Enhancers increase the transcription of any gene. These enhancers can be present upstream or downstream of the gene or a few nucleotides away from the gene. Enhancers act on genes on same DNA molecules. There is expression of WSH gene only in the tail and horn of the unicorns and trolls.

Group 2 scenario: Presence of transcription factor B will silence the gene. As a result, WSH is not expressed. Hence, transcription factor B (TF B) is a repressor/silencer protein that binds to the WSH gene silencing element B in the distal control region of WSH gene. Silencers decrease the transcription of any gene. WSH gene is not expressed in hoof tissue of the unicorn and troll.

3. Differences between group 1 and Group 2:

Group 1

Group 2

There is enhancing or increase in transcription of WSH gene. Element A and C are bound by TFs A and C. This allows RNA polymerase to bind the promoter, enhancing transcription.

There is decrease in transcription of WSH gene. Element B is bound by the TF A , thereby preventing RNA polymerase to access the promoter of WSH gene.

TF A is expressed in tail of unicorns and trolls while TF C is expressed in horn tissues of unicorns of trolls.

TF B is expressed only in hoof tissues of unicorns and trolls.

Wishes will come true for group 1 scenarios as WSH gene transcription is increased. This increase will result in expression of proteins that allow wishes to be fulfilled. Hence, protein translation is also increased.

Wishes will be repressed or not fulfilled for group 1 scenarios as WSH gene transcription is inhibited. This increase will result in inhibition of expression of proteins that are involvement of WSH fulfillment. Hence, protein translation is inhibited.