MSc Sem2, class 2

What does araB gene code for?

• Isomerase

• Epimerase

• Ribulokinase

• beta-galactosidase

Choose all correct points of AraC protein

• coded by araC gene, allosteric, binds araI2 to araI2, heterodimer

• coded by araB gene, allosteric, binds araO2 to araI2, homodimer

• coded by araC gene, allosteric, binds araO2 to araI1, homodimer

• coded by araC gene, allosteric, binds araO2 to araI2, heterodimer

araI1 to araO2 loop of DNA loops which all genes?

• CAP site, araO1 and ParaC

• CAP site, araO1 and ParaBAD

• CAP site, araO2 and ParaC

• CAP site, araO1 and araI2

Explain Steric block in arabinose operon

• RNA loop prevents RNA polymerase from binding to promoter araBAD

• DNA loop prevents RNA polymerase from binding to promoter araBAD

• DNA loop causes RNA polymerase to bind to promoter araBAD

• DNA loop prevents RNA polymerase from binding to promoter araC

Tryptophan operon is?

• Anabolic

• Catabolic

• Amphibolic

• There can be no other option, common guys!

Five genes code for the polypeptides in the enzymes that

convert a tryptophan precursor______________, to tryptophan

• Palmitoic acid

• Chorismic acid

• Acetyl Co-A

• Carbonic acid

When abundant tryptophan is present in the cell, repressor protein remains in an__________form, called as ________because of binding of a _______ which is tryptophan.

• Active, aporepressor, co-repressor

• Active, co-repressor, aporepressor

• Inactive, aporepressor, co-repressor

• Active, co-repressor, aporepressor

Trp leader sequence has 4 clusters with?

• Low levels of self-complimentarity

• High levels of self-complimentarity

• High levels of self similarity

• None

Explain A and B.

• A - Anti-terminator loop, Does not stop transcription of structural genes

  B - Terminator loop, does not stop transcription of structural genes

• A - Terminator loop, Does not stop transcription of structural genes

  B - Anti-terminator loop, stops transcription of structural genes

• A - Anti-terminator loop, stops transcription of structural genes

  B - Terminator loop, does not stop transcription of structural genes

• A - Anti-terminator loop, Does not stop transcription of structural genes

  B - Terminator loop, stops transcription of structural genes

How does attenuation help in trp operon regulation?

• Acts as an primary and only control if negative regulation is not efficient

• Acts as an additional control measure when, negative regulation is not efficient

• Acts opposite to negative regulation mechanism

• None