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1.25.6, , Complementation test, , If two recessive mutations arise, independently and both, are both mutations of the same gene? The, , have the same phenotype, how do we know whether they, complementation test allows us to determine whether two mutations,, both of which produce a similar phenotype are in the same, gene i.e. whether they are alleles or represent mutations, in separate genes, whose proteins are involved in the same function. In genetics,, complementation occurs when, two strains of an organism with different, homozygous recessive mutations that produce the same phenotype, produce offspring with the wild-type phenotype when mated or crossed. Complementation will occur, only if the, mutations are in different genes., , In, , diploid organism the complementation test of allelism (allelism test) is performed by, intercrossing homozygous, recessive mutants two at a time and observing whether or not the, progeny have a wild-type phenotype. If the two, recessive mutations are in separate genes and are, not alleles of one another, then following the cross, all F1, a, , heterozygous for both genes. Complementation is said to occur. Because each mutation is in, a, separate gene and each F1 progeny is heterozygous at both loci, the, normal products of both genes are produced., If the two mutations affect the same gene and, are alleles of one another. Complementation does not occur. Because, progeny, , 224, , are

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Genetics, , the two, , mutations affect the, , same, , gene,, , the F1 is homozygous for the two mutant alieles., , No normal, , product of the, , gene is produced, Case 1: Mutations, , Gene 1, , Mutant, , Mutant, , are in, , separate genes (Trans heterozygote), Gene 1, , Gene 2, , Wild typee, , Gene 2, , Wild type, , Mutant, , Wild type, , Mutant, , X, , wild typee, , Homoiogs, , Gene 2, , Gene 1, Mutant, , Wild type, , Wild type, , Mutant, , One normal copy of each gene is present., Complementation o c c u r s, , Case 2: Mutations are in different locations within the same gene (Cis heterozygote), Gene 1, , Gene 2, , Mutant, , Wild type, , Mutant, , Wild type, , Mutant, , Wild typee, , Mutant, , Wild type, , Gene 2, Wild type, , Mutant, , Wild type, , Mutant, , mutant in, Gene 1 is, , all, , Gene, cases, while, , 2 is, , complementation occurs, , Complementation, , Figure, , Gene 2, , X, , Gene 1, , No, , Gene 1, , 1.195, , analysis., , normal., , Homologs

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Phage complementation, , Crossing, phages by, , infe ting, , Co- infection, , b, , a, , Co- infection involves, the same bacteria with phagesof, different genotypes; once inside, , the cell, crossing over between, viral genomes can occur

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When mixed infection is done using two, different mutants one belonging to ll Athe, other torll B gYoup, the two phages multiply,, cause lysis of host cell and plaques are, , Jórmed., This means that mormal polypeptides of both, mutants, , are, , required, , that is to say, the, , to, , produce plaques, , two complement each, , other., , But if the two, , mutants used for mixed, , infection of K(A) both come from the same, group, either rll A, , they will not be, Vigyantserorases (non-complementing)., or, , rll B,

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CIS TRANS TEST, ml and m2 mutation, , are, , two, , separate recessive mutations that both result in mutantltyp, , Mutant, , Mutant, , WT, , WT, , If both of these mutations, , Mutant, , are, , present, , in, , a, , trans, , configuration, and, , Then these mutations DO NOT, , each other, and are, alleles of same gene, If both of these mutations are present in a trans configuration,, and wild type is observed, , complement, , WT, , Vigyan Sarovar, , Then these mutations, DO complement each, other, and are alleles, of different genes, , mutant, , type is observed