Final answer:
Catalase is the enzyme utilized by anoxia-tolerant yeast and goldfish to maintain cytosolic redox balance under anoxic conditions by decomposing hydrogen peroxide into water and oxygen.
Step-by-step explanation:
The enzyme that anoxia-tolerant yeast and goldfish use to maintain cytosolic redox during anoxia is catalase. This enzyme catalyzes the reaction where hydrogen peroxide (H2O2) is broken down into water (H2O) and molecular oxygen (O2). Specifically, the reaction it catalyzes can be summarized as: 2H2O2 → 2H2O + O2. Catalase plays a critical role in protecting cells from oxidative damage by reactive oxygen species (ROS) like hydrogen peroxide, which can be particularly harmful during anoxic or low-oxygen conditions. Furthermore, in the context of redox reactions and oxygen sensing in cells, it's worth mentioning that high-altitude Andean populations have a gene with a fixed single nucleotide variation for a protein kinase (AMPK encoded by PRKAA1), which is part of a broader system for oxygen detection and response. AMPK is linked to mitochondrial oxidative phosphorylation and can directly signal respiratory control centers.