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Q86. The following graph represents the expression of Tryptophan Synthetase (TS) in E.coli cels in absence or presence of Tryptophan in the medium-
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Q86. The following graph represents the expression of Tryptophan Synthetase (TS) in E.coli cels in absence or presence of Tryptophan in the medium-
If the two trp codons in the leader sequence of trp operon is mutated to ala, which of the following graph will best represent activity of TS in E.coli cells grown in the absence or presence of tryptophan?
(A)
(B)
(C)
(D)
ANSWER-B
Description-42-45 nucleotide coding leader sequence(trpL) contains an attenuator site.
Att-Transcription termination loop.(3:4)
Q87.The lifetime of a peptide bond in protein is very large,which statement below is incorrect with respect to stability of peptide bond?
(A)free energy of hydrolysis is negative
(B)The free energy of hydrolysis is positive and large
(C)The energy barrier to be crossed to go to the hydrolysed state in the large
(D)The peptide bond can be hydrolysed by6N HCl at 100 degree C.
ANSWER-B
Description-Because peptide bond hydrolysis is a spontaneous process. so it have highly negative value.
Q88. Following are certain statements related to euckryotic DNA replication-
1.The genome of multicellular animals contain many potential origins of replication.
2. During early development, when embryos are undergoing rapid cell divisions origin sites are uniformly activated.
3.'Pulse-chase' technique is used to label sites of DNA replication.
4.The rate of elongation of different DNA chains during genome replication varies drastically.
Which one of the following combinations of above statements are correct?
(A)1,2 and 3
(B)1,3 and 4
(C)2,3 and 4
(D)1,2 and 4
ANSWER-A
Description-Because the size of Eukaryotic genome is very large so,it contains multiple ori, uniformly transcribed at each ori, during early development stages.
'Pulse-chase' technique is also used to label the sites of DNA replication.
Method was used to determine the existence and function of Okazaki fragments(DNA replication)
Q89.A researcher wanted to immunize individuals of a particular area with viral infections. The researcher developed two different vaccine types(A and B) with the following properties-
1.When vaccine type A specific for a viral strain is administered to individuals, they develop strong neutralizing antibody response with very poor immunological memory.Hence it has to be administered in repetitive doses.
2.When vaccine type B specific for a viral strain is administered to individuals, they fail to develop circulating antibody response at the time of infection but they develop strong immunological memory.
If two viral strain V1(incubation period-2 days) and V2(incubation period-15days) are likely to infect the area which of the following vaccine combination would provide maximum immunization?
(A)V1 specific type A and V1 specific type B
(B)V1 specific type A and V2 specific type B
(C)V2 specific type A and V1 specific type B
(D)V2 specific type A and V2 specific type B
ANSWER-B
Description-Type A specific type to viral strain, produces strong neutralizing Abs but very poor immunological memory.
Hence repetitive booster doses are required.
But type B vaccine is generating strong memory.
Therefore to control V1 viral strain and V2, a combination of type A and B vaccine should be beneficial.
Q90.The expression of a hypothentical gene was analysed by Northen and Westenbolt hybridizations under control and induced condition.The results are summarized blow-
Expression of gene can be regulated by-
1.control at transcription initiation
2.alternative splicing
3.control the translation initiation
4.protein stability
Which of the above regulatory mechanisms can explain the observations show in the figures?
(A)Only 2
(B)Only 1 and 2
(C)Only 2 and 3
(D)1,2,3 and 4
ANSWER-D
Description-Northern bolt hybridization-RNA
Western bolt hybridization-Protiens
Expressions of gene can be regulated at any of following stages-A,B,C and D.
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