# Millennium Problems for Biology > 12 biology challenges to solve. - Title: Millennium Problems for Biology · Millenniumproblems - Summary: 12 biology challenges to solve. Scientists aim to create self-replicating cells, regrow mouse limbs, and engineer enzymes for medical breakthroughs. - Keywords: self-replicating cells, mouse limb regeneration, reverse translatase, rubisco enzyme, quadruplet cell, somatic limb regeneration, bacterial gene therapies, programmable proteases, cell-penetrating binders, protein amplification, 5 polymerases, new nitrogenases - Source: Millenniumproblems — https://millenniumproblems.bio - Author: The Twelve Problems - Read time: 1 min - Topics: self-replicating cells, mouse limb regeneration, reverse translatase, rubisco enzyme, quadruplet cell, somatic limb regeneration, bacterial gene therapies, programmable proteases, cell-penetrating binders, protein amplification, 5 polymerases, new nitrogenases ## Origins of life Demonstrate self-replicating cells from chemical precursors. > unassisted emergence of self replicating RNA and protein based cells ## Cryopreservation Recover live wild-type mice after 24 hours frozen. > reversible cryopreservation of live intact wild type adult mice ## Reverse translatase Create enzyme that converts peptides to RNA or DNA. > reverse translate arbitrary peptide sequences into RNA or DNA ## Improve Rubisco Engineer Rubisco for better carbon dioxide specificity. > Rubisco with higher specificity for carbon dioxide over oxygen ## Quadruplet cell Build cell using four-base codon genetic code. > living cell with four base codon code for proteins ## Somatic limb regeneration Regrow mouse limbs after amputation. > reproducible ability to regrow lost mouse limbs ## Bacterial gene therapies Produce gene therapies in bacteria. > infectious replication incompetent AAV and lentivirus in bacteria ## Programmable proteases Design enzymes to cut specific protein sequences. > proteases that cleave specific protein sequences efficiently ## Cell-penetrating binders Create proteins that target intracellular proteins. > zero-shot protein binders for intracellular targets ## Protein amplification Amplify peptides without nucleic acid templates. > exponential amplification of arbitrary peptide substrates ## 5 Polymerases Build 5' acting polymerases. > complete set of 3 prime to 5 prime polymerases ## New nitrogenases Create nitrogenase without natural homology. > nitrogenase converting nitrogen to ammonia without natural similarity ## Key takeaway Scientists aim to create self-replicating cells, regrow mouse limbs, and engineer enzymes for medical breakthroughs.