Gene expression environmental factors and metabolic pathways

What is a metabolic pathway?

A series of interconnected, enzyme-controlled biochemical reactions inside a cell, where the product of one reaction becomes the substrate for the next.

What does the One-Gene-One-Enzyme relationship refer to?

The concept that each individual step in a metabolic pathway is regulated by a specific enzyme, encoded by one distinct gene.

What defines enzyme specificity?

Enzymes have a highly specific 3D tertiary structure and a uniquely shaped active site, allowing them to bind only to one complementary substrate.

What is necessary for the expression of a normal phenotype in a metabolic pathway?

Every gene in the pathway must be expressed normally via transcription and translation to produce functional enzymes, leading to successful substrate conversion.

What happens when there is an upstream mutation in a metabolic pathway?

It alters the DNA sequence, producing a non-functional enzyme, leading to pathway stoppage and no downstream products being made.

What is the effect of a downstream mutation on a metabolic pathway?

Upstream enzymes work normally, but the mutated downstream enzyme is non-functional, causing intermediate substrates to accumulate and preventing final product synthesis.

What role do environmental co-factors play in enzyme function?

They are essential nutrients or co-enzymes that must bind to an enzyme for it to achieve its functional shape and catalyze its specific pathway step.

What occurs during co-factor deficiency?

The genotype is normal, but the enzyme produced is inactive without the co-factor, leading to accumulation of the intermediate substrate and blockage of the final product.

How can extreme temperature or pH affect enzymes?

They can denature enzymes by breaking the bonds that maintain their structure, altering the active site and preventing substrate binding.

What are the similarities between genotype and environment in metabolic pathways?

Both can result in the same final phenotype by stalling the metabolic pathway and preventing final product formation.

What are the differences between genotype and environment regarding mutations?

A mutation permanently alters the genotype, while environmental factors do not change DNA but disrupt normal protein function.

What is the phenotype equation?

Phenotype = Genotype + Environmental Factors.