You are studying a new strain of E. coli that can utilize the disaccharide melibiose very efficiently. You find that utilization depends on the enzyme melibiase, which is encoded by the gene Mel1. Mel1 is not expressed unless melibiose is present in the growth medium. You have isolated a mutation that causes constitutive melibiase activity, which you designate MelA–. P1 phage mapping experiments using a Tn5 insertion linked to Mel1 show that MelA– is not linked to Mel1. Moreover you find that when an amber suppressor is introduced into a MelA– mutant, normal melibiase regulation is restored. Classify the MelA– mutation on the basis of genetic properties,  make a proposal for the type of regulatory functions affected by the MelA– mutation?

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#Question id: 13071

#Unit 13. Methods in Biology

Modifications of the agglutination reaction involve the use of ________particles, which allow the reaction to be observed more easily in the liquid phase

TLS Online TPP Program

#Question id: 13072

#Unit 13. Methods in Biology

Inheritance pattern of RFLP and RAPD markers for genome mapping in plants;

TLS Online TPP Program

#Question id: 13073

#Unit 13. Methods in Biology

Restriction enzymes must be use in RFLP and RAPD markers for genome mapping in plants;

TLS Online TPP Program

#Question id: 13074

#Unit 13. Methods in Biology

Type of probe used in RFLP;

TLS Online TPP Program

#Question id: 13075

#Unit 13. Methods in Biology

Radioisotopes must be used in RFLP and RAPD markers

TLS Online TPP Program

#Question id: 13076

#Unit 13. Methods in Biology

Restriction fragment length polymorphism denotes that a single restriction enzyme produces fragments of different lengths from the same stretch of genomic DNA of different strains of a species or from different related species. RFLPs are detected as follows:

i.  Large molecular weight genomic DNA is isolated from several strains or related species;

ii.  The fragments in these digests are separated through electrophoresis

iii.  These 'DNAs are then digested with a selected restriction enzyme

iv.  Exposed to a suitably radio-labelled appropriate DNA probe under conditions favouring DNA: DNA hybridization

v.  The resulting gel lanes are transferred and fixed to a suitable solid support and

vi.   The free probes are removed

vii.  The fragments to which the probe has hybridized are detected by filming them as distinct bands on a suitable photofilm through autoradiography.