Update cloze 1 from "electrons" to one electron. This concept is tested on the AAMC unscored sample exam by asking how many electrons cyctochrome c can carry in oxidative phosphorylation. Jack westin also states "Cytochromes are a family of related proteins that have heme prosthetic groups containing iron ions. Electrons are passed from one cytochrome to an iron-sulfur protein to a second cytochrome, then finally transferred out of the complex to a mobile electron carrier cytochrome C, which can only carry one electron at a time." Here is the link to this information: https://jackwestin.com/resources/mcat-content/oxidative-phosphorylation/electron-transfer-in-mitochondria