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#metabolic pathways

3 public questions tagged with this topic.

Gene Dissection and Complementation

In genetic dissection, the supplement that restores growth indicates

Supplementation test interprets growth restoration as evidence that supplied compound lies downstream of metabolic block in pathway. Auxotroph unable to synthesise its own product depends on exogenous molecule, and only molecules occurring after defective step can be utilised because earlier molecules still need defective enzyme for conversion. Pattern of rescue across many mutants therefore distinguishes upstream versus downstream intermediates enabling determination of gene order. Column with many positives indicates early metabolite rescuing many blocks while narrow rescue indicates late metabolite position in sequence.

Ref: Hartl & Ruvolo, Genetics, 6th ed., Chapter 14: Pathway Analysis Using Auxotrophs Rescue Principle

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Enzyme Inhibition

Which statement about feedback inhibition is correct?

The product of a metabolic pathway inhibits the first enzyme in the pathway is the accurate response regarding enzymatic activity or regulation described in this question. Enzymes are biological catalysts that accelerate reactions by lowering activation energy through specific substrate binding and transition state stabilization. In the context of Enzyme Inhibition, The product of a metabolic pathway inhibits the first enzyme in the pathway plays a specific catalytic or regulatory role determined by its active site configuration and mechanism of action. The other options (The product enhances enzyme activity, The product binds only to the active site, and The inhibitor is always competitive) are either different enzymes with distinct substrate specificities, act through different mechanisms, or are involved in separate metabolic pathways.

Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 6

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