Question

john gurdon performed nuclear transplant experiments in frogs to test two different hypotheses to explain why specialized cells become restricted in their fates during development. his results supported the hypothesis that differentiation involves genome regulation, where unneeded genes are progressively turned off but are not lost from the genome of cells as they differentiate. however, gurdon's results showed that only 10 out of 726 eggs that received transplanted nuclei from mature cells differentiated into tadpoles, whereas 716 did not.why did gurdon use these rare successful nuclear transplantations as evidence for the gene regulation hypothesis?

Answer 1

Gurdon's successful nuclear transplantations, although rare, provided evidence for the gene regulation hypothesis by showing that differentiated cells retain all genes necessary for forming an organism and that differentiation relies on gene expression rather than loss of genetic material.

Step-by-step explanation:

John Gurdon utilized nuclear transplant experiments in frogs to shed light on cellular differentiation processes. While many of the eggs with transplanted nuclei did not successfully develop into tadpoles, the few that did were crucial. These rare successes were evidence that specialized cells, despite their differentiation, still retained a complete genome capable of directing full organismal development when reprogrammed. This supports the hypothesis that during differentiation, gene regulation takes place through the selective expression of genes rather than the loss of genetic material.

This finding was instrumental in demonstrating that all somatic cells in an organism, regardless of their specialized functions, contain the same DNA (genes). The uniqueness of various cell types stems not from a difference in gene content but rather from a difference in gene expression. Cellular differentiation occurs when certain genes are activated and others are deactivated, based on regulatory mechanisms such as transcription factors.

In essence, Gurdon's experiments showed that the potential for an entire organism's development lies within each cell's nucleus, affirming the concept of genomic totipotency. This foundational concept has propelled further studies in gene regulation, organogenesis, and has informed the stem cell research field, all important areas of developmental biology.