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Faculty Mentor

Dr. Arthur Omran, Lecturer

Faculty Mentor Department

Chemistry & Biochemistry

Abstract

Phosphorus is a minor element with a cosmic abundance of about 105.5 atoms per 1012 H atoms (Boudreaux, n.d.). Phosphorus was depleted as a volatile throughout the developing solar system, and as a result, volatile forms of phosphorus would have been minimal, even in the colder regions of the solar nebula. Despite its low abundance, phosphorus minerals play key roles in planetary petrology, including through the formation of phosphate minerals that trapped volatiles and rare Earth elements, and in the formation of metal phosphides that may have served as nucleation sites for kamacite and taenite crystal growth in minor planet cores (Pasek, 2019). Calculations of the condensation sequence of the element phosphorus indicate that phosphorus will be primarily sequestered into metal phases and the mineral schreibersite—(Fe,Ni)₃P—at high temperature (700–1100 K at 10−4 atm), and into phosphate minerals such as apatite, Ca5(PO4)3(OH,F,Cl), and whitlockite/merrillite Ca9(Mg,Fe)(Na,H)(PO4)7, at lower temperatures (300–700 K) (Pasek, 2015).

The early Earth and impact-delivered mineralogy of phosphorus also affected how P was incorporated into primordial prebiotic chemistry. Prebiotic conditions continue to be one of the defining issues for the role of phosphorus in the origins of life processes. Phosphorus in life is needed for the growth, maintenance, and repair of all tissues and cells, and to produce the genetic building blocks, DNA and RNA. Phosphorus is also needed to help balance and use other vitamins and minerals. Phosphorus, like nitrogen, is a critical nutrient required for all life. The most common form of phosphorus used by biological organisms is phosphate (PO₄), which plays major roles in the formation of DNA, cellular energy, and cell membranes (Fernández-García et al., 2017). We know water to be a fundamental part of the ingredients that formed the initial conditions that allowed life to come about. The ease with which such amidophosphates or phosphoramidate derivatives phosphorylate a wide variety of substrates suggests that alternative forms of phosphate could have played a role in overcoming the “phosphorylation in water problem” (Pinna et al., 2022).

Two important aspects of prebiotic phosphate chemistry should be taken in account when searching for the initial mechanism that brought about life: First are the prebiotic phosphorylation reactions; specifically contrast aqueous electrophilic phosphorylation, and aqueous nucleophilic phosphorylation strategies, with dry-state phosphorylations that are mediated by dissociative phosphoryl-transfer (Fernández-García et al., 2017). Second are the non-structural roles that phosphates can play in prebiotic chemistry. Here the focus will be on the mechanisms by which phosphate has guided prebiotic reactivity through catalysis or buffering effects, to facilitating selective transformations in neutral water (Fernández- García et al., 2017). Several prebiotic routes towards the synthesis of nucleotides, amino acids, and core metabolites, that have been facilitated or controlled by phosphate acting as a general acid–base catalyst, pH buffer, or a chemical buffer will be outlined.

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