Experiments have shown that a defective gene gives a defective enzyme. Hence there is argument of that one gene is responsible for making one enzyme. Discuss whether this statement is correct or not. Give ONE example to support.
The statement that one gene is responsible for making one enzyme is an oversimplification of the relationship between genes and enzymes. While it may be true in some cases, it is not universally accurate for all genes and enzymes.
To understand this, we need to delve into the concept of the one gene-one enzyme hypothesis. This hypothesis was proposed by Beadle and Tatum in the early 1940s based on their experiments with the bread mold Neurospora crassa. They found that mutations in specific genes of the mold resulted in the inability to produce certain enzymes, leading to metabolic deficiencies.
However, as our knowledge of genetics and molecular biology advanced, it became apparent that the relationship between genes and enzymes is more complex. Not all genes code directly for enzymes; some genes may encode structural proteins, signaling molecules, or regulatory elements that control the production of enzymes. Additionally, genes can undergo alternative splicing, producing various proteins with different functions from a single gene.
To support this, let's consider the example of the gene known as CFTR (cystic fibrosis transmembrane conductance regulator). Mutations in the CFTR gene cause cystic fibrosis, a genetic disorder that affects multiple organ systems in the body, including the lungs and digestive system.
The CFTR gene encodes a protein that functions as a chloride ion channel on the surface of cells. Chloride ions play a crucial role in maintaining normal fluid balance in various tissues. However, the CFTR protein is not an enzyme itself; it acts as a regulator of ion transport, impacting the function of multiple enzymes and channels involved in fluid regulation.
Therefore, in this example, a single gene (CFTR) affects the function of multiple enzymes indirectly by controlling the transport of chloride ions. This demonstrates that the relationship between genes and enzymes is not as simple as the one gene-one enzyme hypothesis suggests.
In conclusion, while the one gene-one enzyme hypothesis was a groundbreaking concept in understanding the relationship between genes and enzymes, it has been refined through further research. Many genes have diverse roles beyond encoding enzymes, and a single gene can impact the function of multiple enzymes indirectly. Hence, it is essential to recognize the complexity and nuances of gene-environment interactions in the context of enzyme production and function.