Q2CC Explain how multiple exons might... [FREE SOLUTION]

Chapter 21: Q2CC (page 440)

Explain how multiple exons might have arisen in the ancestral EGF and fibronectin genes shown on the left side of Figure 21.16.

Short Answer

Expert verified

According to figure 21.16, the ancestral genes EGF (Epidermal Growth Factor) and fibronectin genes are shown to carry multiple exons.

The duplication of exons might result from incorrect homologous pairing, crossing over of misaligned non-sister chromatids, transpositions, and continuous duplication and mutation of EGF and fibronectin gene.

Step by step solution

Exons

Exons are the part of a genetic code that is specifically responsible for particular protein domains. Exon can either duplicate or get deleted from a chromosome.

The gene containing duplicate exons would change protein structure, affecting and altering the protein stability and functions.

Exon duplication in the ancestral genes

Exon shuffling can make new genes by accumulating exons from different genes; this might cause exon duplication. According to the figure, multiple exons arise from the EGF and fibronectin genes. The multiple exons must have arisen due to duplication and mutation of the ancestral genes.

The exons would have been further subjected to transposition and continued subsequent duplication and mutation. The abovementioned processes assisted by gene duplication; the exon duplication would have arisen in the ancestral EGF and fibronectin.

Transposable elements and crossing-over of erroneous alignment of non-sister chromatids lead to exon duplication at the molecular level.

Multiple exons in the ancestral EGF and fibronectin

The multiple exons in the ancestral gene arise due to a series of mutations and duplication of the same DNA. DNA duplication occurs due to several errors in genetic processes.

When the duplicated and mutated genes are transpositions to different chromosomes over prolonged durations, multiple exons appear in the ancestral genes.