Question

1. Which regulatory proteins are normally bound to the Psf promoter in the presence of Mg²⁺ only?

1. None

2. MetA only

3. MetA and MetB

4. MetA, MetB, and MetC

2. Which of the following regulatory proteins are likely to act as gene activators?

1. MetA only

2. MetB only

3. MetC only

4. Both MetA and MetC

3. Secondary structure in the 5’ UTR of mRNA can form a secondary structure that is stabilized by small molecules and can interfere with transcription. This mechanism is known as_______ and is found in ______.

1. Attenuation, bacteria only

2. Attenuation, eukaryotes only

3. Ribo switch, eukaryotes only

4. Ribo switch, bacteria only

5. Ribo switch, both bacteria and eukaryotes

4. The consensus sequence for a bacterial promoter is listed below along with the promoter sequences for several genes. Which gene has the strongest promoter?

1. trp

2. lac

3. recA

4. araBAD

5. Dnaj

Need help with questions #1-4 please

Answer 1

1. C (Both MetA and MetB must be bound, because Psf is not normally transcribed in the presence of Mg2+ only. When the binding site for MetA is present without any other binding sites, low levels of Psf transcription occur in the presence of Mg2+ only, suggesting that the gene activator MetA binds in the presence of Mg2+. Because no transcription occurs normally, the gene repressor MetB must also bind to DNA in the presence of Mg2+)

2. Both MetA and MetC.

3. Riboswitch, both bacteria and eukaryotes.

4. Lac and DNAj gene have strongest promoter

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