Tag: inherited changes

The inducible operon is usually off and it can be induced in the presence of inducer like lactose. After getting induced, the operon is turned on and transcription takes place to catabolize these inducers. Hence, the inducible operon is usually involved in catabolism. 

Repressible operons are generally involved in anabolic pathways, or the synthesis of an essential component, while inducible operons are generally involved in catabolic pathways or the breakdown of a nutrient. Positive control of an operon is when gene expression is stimulated by the presence of a regulatory protein. The repressible operon work on the feedback inhibition mechanism which is the phenomenon where the output of a process is used as an input to control the behavior of the process itself and the co-repressor serves as to activate the repressor. Genes of a repressible operon are switched off as they are required to synthesize the structural/functional genes in the absence of the repressor. The presence of the repressor can stop this process and hence the repressor is present in the inactive form. 

Alleles are alternative forms of a gene. They are responsible for differences in phenotypic expression of a given trait. When a gene exists in three or more allelic forms it is called multiple allele. Homologous chromosomes are chromosome pairs, one from each parent. They are similar in length, gene position and centromere location. Multiple alleles are situated in homologous chromosome at the same locus. Thus the correct answer is option A.

Albinism is a autosomal genetical recessive gene disorder. It occurs in homozygous recessive state. The gene for albinism is a. it does not produce the enzyme tyrosinase, but is normal Allele A is does. Thus only homozygous individuals (aa) is affected. When both parents are albinic, all the offsprings also albinic generally.

So, the correct option is ‘Albino’.