Explain how the following mutations would affect the transcription of the yeast GAL1 gene.

Can someone please help me understand the answers to these questions?I would really appreciate it!


Explain how the following mutations would affect the transcription of the yeast GAL1 gene.

A) A deletion within the GAL4 gene that removes the region encoding amino acids 1 to 100:
    ANSWER: A deletion within the GAL4 gene that removes amino acids 1-100 would remove the DNA-binding section and not allow transcriptional activation.

B) A deletion of the entire GAL3 gene.
   ANSWER: Without the product of the GAL3 gene, there would be no disruption of the Gal4p/Gal80p complex and therefore no transcription of the GAL1 gene.

C) A mutation within the GAL80 gene that blocks the ability of Gal80 protein to interact with Gal3p.
  ANSWER: If the GAL80 gene product can’t interact with Gal3p, there can be no interaction with
           the Gal4p/Gal80p complex and therefore no GAL1 transcription.

D) A deletion of one of the four UASG elements upstream from the GAL1 gene.
   ANSWER: A deletion of one of the four UASG elements would reduce transcription of the GAL1 gene.

E) A point mutation in the GAL1 core promoter that alters the sequence of the TATA box.
   ANSWER: Generally, mutations in the TATA box of a promoter reduce transcription of the
           relevant gene.


Explanations are greatly appreciated! Thank you!