Question

A mutant strain of E. coli produces β-galactosidase in the presence and in the absence of lactose. Where in the operon might the mutation in this strain occur and why?
A-in the operator region, where the mutation leads to the failure of the operator to normally bind the repressor

B-in the CAP binding site, where the mutation leads to the inefficiency of RNA polymerase activity

C-in the promoter region of the operon, where the mutation leads to the failure of the RNA polymerase to bind to the promoter

D-near the lacI gene, where the mutation leads to increased levels of lac repressor being made

E-in the lacI gene, which leads to an inactive lac repressor

F-in the operator region, which leads to increased binding of the lac repressor to the operator

Answer 1

The correct answer is (A and E) The operator region where the mutation occurs and the operator does not binds to the repressor normally.The mutation can also occur in the Lacl gene which leads to an inactive lac repressor.

• The lacI gene helps in regulation of lac operon. It is also responsible for the metabolism of lactose in bacteria.

• The mutation could have occured in the operator region, where after mutation the repressor would not be able to bind to operator.

Answer 2

A & E

Further explanation

Recombinant proteins such as vaccines, antibodies, hormones, and medicines are increasingly needed by livestock and humans. The main obstacle to producing recombinant proteins in Escherichia coli as the most widely used host is degradation by proteolytic enzymes. This is because E. coli has a number of proteolytic enzymes that are spread in the cytoplasm. For this reason, more than 90% of protein degradation occurs in the cytoplasm. In this study, researchers have produced mutants E. coli BW25113 that do not have a protease enzyme coding gene using a combination of chromosome destruction and phage P1 transduction methods. The making of the mutant begins with the destruction of the protease enzyme coding gene on the bacterial chromosome with a PCR product which has a homologous portion with the target gene. The mutants produced are then used to produce double mutants using the Phage P1 Transduction method. Phenotive and genotive analysis shows that the combination of the two methods is very effective for making more than one mutation in E. coli. For this reason, E. coli mutants that have been obtained will be very useful to produce various recombinant proteins for livestock and humans.

Beta-galactosidase or β-galactosidase is one of the hydrolase enzymes included in the fig operon whose function is to accelerate the conversion reaction from galactosides to galactose, such as lactose to monosaccharides namely galactose and glucose.

These enzyme substrates include GM1 gangliosides, lactosylceramides, lactose, and various glycoproteins. [Citation needed]

This enzyme is coded by lacZ and has an isomer called α-galactosidase (melibiase).

In humans, this glycoprotein has a length of 677 AA, encoded in the GLB1 or ELNR1 gene and has 2 isomers that live in the perinuclear cytoplasm and lysosomes

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Beta-galactosidase : brainly.com/question/11758698

Details

Class: high school

Subject: biology

Keywords : galactosidase, enzyme, e. coli, mutans