Question

In: Biology

2. The -10 core promoter of the lac operon gene has the sequence TATGTT. Describe an...

2. The -10 core promoter of the lac operon gene has the sequence TATGTT. Describe an example of a base substitution mutation which would lead to increase transcription of the gene. Explain whether this mutation would increase or decrease the fitness of the organisms.

Solutions

Expert Solution

The lac promoter is not a particularly strong promoter, and mutations have been obtained that either increase or decrease its efficiency of initiating transcription. The given -10 promoter sequence is TATGTT is not a strong promoter and therefore  Base substitutions(G to A) will make the promoter sequence more similar to the consensus sequence (TATATT) which will generate a stronger promoter (promoter "up" mutations). An "up" mutation would make the lac operon no longer dependent on the positive regulation by the cAMP?CAP complex (when the operon is induced) and will show an inducible phenotype.

E.coli has about 4500 genes. Some genes are constitutively expressd or some genes are expressed only under certain conditions. Because of Base substitution (transition from G to A), the promotor becomes a strong one and regulate transcription more strongly even in harsh environment thereby increasing transcription.This ability to regulate gene in harsh environment is ADAPTATION- increasing fitness.


Related Solutions

Describe the likely effect on gene expression of a mutation in the lac operon: a) that...
Describe the likely effect on gene expression of a mutation in the lac operon: a) that delegate the operator b) that mutates the lacI gene inactivating the repressor c) that the promoter mutates in the -10 region
what is the function of the gene products encoded by the lac promoter? Describe how thr...
what is the function of the gene products encoded by the lac promoter? Describe how thr operon is controlled by the lac repressor protein (LacR)
The map of the lac operon is:    POZY   The promoter (P) region is the start site of...
The map of the lac operon is:    POZY   The promoter (P) region is the start site of transcription through the binding of RNA polymerase before actual mRNA production. Mutationally altered promoters (P-) cannot bind RNA polymerase. Certain predictions can be made about the effect of P- mutations. Use your predictions and your knowledge of the lactose system to complete the following table. Insert a “+” where an enzyme is produced and a “-“ where no enzyme is produced. The first one...
10. Mutations in the lacI gene (lacI-) constitutively transcribe the lac operon. Mutations in the operator...
10. Mutations in the lacI gene (lacI-) constitutively transcribe the lac operon. Mutations in the operator region can also occur, also resulting in the constitutive expression of the lac operon. Using the “reagents” described below, design an experiment to test if a mutant that constitutively expresses the lac operon is mutated in the lacI gene or in the operator. X-gal – a colorless chemical that is a substrate for B-galactosidase, when cleaved it produces a blue dye that “stains” any...
27. Be able to describe regulation of gene expression in prokaryotes (transcriptional, like the Lac Operon)...
27. Be able to describe regulation of gene expression in prokaryotes (transcriptional, like the Lac Operon) and in eukaryotes (transcriptional and epigenetic regulation).
Draw the lac operon promoter region with all its regulators (and polymerase if appropriate) in the...
Draw the lac operon promoter region with all its regulators (and polymerase if appropriate) in the PRESENCE OF LACTOSE and the ABSENCE OF GLUCOSE in the growth media in bacteria with a mutation in the lac repressor which prevents it from binding lactose and a mutation in the CAP that prevents it from binding cAMP. Indicate the level of transcription from the lac operon under those conditions (no expression, low expression, or high expression).
Predict the level of gene expression of the lac operon, as well as the status of...
Predict the level of gene expression of the lac operon, as well as the status of the lac repressor and the CAP protein, when bacterial growth media contains the following sugars: a) no lactose or glucose, b) lactose but no glucose, c) glucose but no lactose, d) both lactose and glucose.
Explain what are gene regulatory operons,with lac operon and tryptophan operon examples by drawing figures for...
Explain what are gene regulatory operons,with lac operon and tryptophan operon examples by drawing figures for each?
The promoter is an important sequence for transcription of a gene. Which of these components binds to the promoter of a eukaryotic gene to allow transcription to begin?
The promoter is an important sequence for transcription of a gene. Which of these components binds to the promoter of a eukaryotic gene to allow transcription to begin? Select all that are correct.A. Ribosomal subunitsB. A start codonC. DNA polymerase enzymeD. General transcription factorsE. RNA polymerase enzyme
Explain how gene regulation occurs using the lac operon as an example.
Explain how gene regulation occurs using the lac operon as an example.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT