Antibiotic-resistant strains of Mycobacterium tuberculosis are a major problem when treating TB. A new antibiotic, teixobactin, could be very effective at killing M. tuberculosis with only a small risk that the bacteria will evolve teixobactin resistance. Penicillin and similar antibiotics bind to a single protein, but teixobactin binds to two lipids that are needed for the formation of the bacterial cell wall. Teixobactin binds to regions of the two lipids that do not vary across many different species of bacteria. Which statements help to explain why the use of teixobactin is thought to be less likely to lead to the evolution of antibiotic resistance than the use of many other antibiotics, such as penicillin? 1 A single mutation can result in bacteria that are resistant to penicillin and similar antibiotics but at least two mutations are required to produce teixobactin-resistant bacteria. 2 Mutations can affect the structure of proteins but cannot affect the structure of lipids because only proteins are made of amino acids. 3 The lack of variation across many species of bacteria in the two lipids that bind to teixobactin suggest that the particular structure of these lipids is essential for successful bacterial cell wall formation.