18. in the operon of lactose, what molecule acts as inducer? A) glucose B) perme

Question

18. in the operon of lactose, what molecule acts as inducer?

A) glucose
B) permeasa
C) alolactose
D) B-galactosidase
E) transacetylasa

21. In the presence of glucose, where will the repressor of the lactose operon be attached?

A) lacZ
B) lacO
C) lacP
D) lacl
E) the repressor does not bind to the Operon

22. What structural gene of the lactose operon can mutate without affecting the ability of a cell to use lactose?

A) lacZ
B) lacY
C) lacA
D) lacP
E) lacO

23. Which of the following can mutate and result in the constitutive expression of the lactose operon?
A) lacZ and lacP
B) lacZ and lacl
C) lacO and lacl
D) lacO and lacZ
E) lacl and lacY

24. which of these strains haploides produces B - galactosidase constitutively but not produces permeasa?
A) I- P+ O+ Z+ Y+
B) I+ P+ O+ Z+ Y-
C) I- P+ O+ Z- Y+
D) I+ P+ O- Z+ Y+
E) I- P+ O+ Z+ Y-

25. which of these strains haploides produces permeasa but not produces B - galactosidase?

A) I- P+ O+ Z+ Y+
B) I- P+ O+ Z- Y+
C) I- P+ O+ Z- Y-
D) I+ P+ O- Z+ Y+
E) I- P+ O+ Z+ Y-

26. During the attenuation of the Operon trp. Which link leads to the synthesis of a polycistronic mRNA when there is no available tryptophan?

A) loop 1-3 (anti-termination)
B) loop 3-4 (termination)
C)loop 1-2 (pause)
D) loop 2-3 (anti-termination)
E) loop 2-4 (termination)

27. in absence of tryptophan

A) the repressor inactive unable to unite trpO, so it is transcribed genes operon
B) the repressor active joins trpP, so that represses transcription of genes
C) inducer unable to unite trpO, so transcription genetic occurs
D) the repressor active unable to unite trpo, so transcription of genes is attenuated
E) the repressor joins corepresor, and transcription of genes operon occurs

28. the operon of tryptophan, where is located region attenuator?

A) trpP
B) trpO
C) trpL
D) trpE E) trpD

29. what molecule functions as the corepresor in the operon trp?
A) ATP
B) tryptophan
C) loop 3-4
D) CAMP
E) glucose

31. how many secondary structures (ties) different can be form of mRNA in the region leader (trpL)?
A) one
B) two
C) three
D) four
E) five

31. which of these mutations will result in increased decrease in the efficiency of attenuation?
A) mutations preventing training loop 1-2
B) mutations preventing training loop 2-3
C) mutations preventing training loop 3-4
D) mutations altering the uracil in the end 3 'and Poly-or
E) a and e

Explanation / Answer

Answer=

18. in the operon of lactose, what molecule acts as inducer?

C) alolactose
Explination-

when an inducer is present,it binds to the allosteric site of the Lac repressor,thereby inactivatingthe operator DNA -binding site of Lac repressor protein.however lactose itself does not have this effect but allolactose have

therefore allolactose is actual inducer of lactose operon.

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21. In the presence of glucose,the repressor of the lactose operon be attached

B) lacO

Explaination- if the glucose is present in high concentration,the lac repressor binds to the lac operator site.

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