Question

Cis-trans expression of genes is an example of
A. Mutation
B. Intergenic crossing over
C. Intragenic crossing over
D. Cytoplasmic inheritance

Answer 1

Hint: Areas of non-coding DNA that control the transcription of neighboring genes are cis-regulatory elements (CREs).

Complete Answer:
In the region of the genes which they control, CREs are found. By attaching to transcription factors, CREs usually control gene transcription. A single transcription factor can attach to several CREs and thus regulate many genes' expression.

Now, let us find the solution from the options-
- Mutations are consistent with the Cis-trans test. The Cis-trans test is a test which decides when two mutations exist in the same gene or in multiple genes which have the same effect. Either in cis-position or trans-position, the mutation can be occur.
- A stretch of DNA sequences found within genes is an Intergenic region (IGR). Intergenic regions are a type of non-coding DNA. Any intergenic DNA sometimes functions to regulate neighbouring genes, but much of it has no known role at present. Thus, option B is not the correct option.
- New alleles can be produced by INTRAGENIC recombination among two separate established alleles in a population. The role of this approach has been investigated in preserving variation in a natural population by suggesting which gene comprises two sites, each of these can mutate to an unlimited number of specific 'alleles'. Thus, option C is not the correct option.
- The inheritance of nuclear chromosome genes is distinguished by the fact that the females and males parents' genes lead equally to the offspring’s genetic development. Therefore, with the exception of sex-linked genes, reciprocal crosses between parents with separate homozygous genotypes would create offspring with similar phenotypes. Thus, option D is not the correct option.

Thus, the correct option is option (A) Mutation.

Note: By modifying the way TFs attach, mutations occurring within a CRE will produce expression variability. For up- or down-regulated transcription, stronger or looser linking of regulatory proteins will follow.