What is NOT true about primary protein structures? A. the core of the primary structure is a repeating three atom repeating unit B. the core unit consists of amino nitrogen, carbonyl carbon, alpha carbon C. because of steric hinderance certain amino acid sequences cannot occur D. the amino nitrogen and the carbonyl carbon come from the alpha amino and alpha carboxyl group of amino acids E. The alpha carbon can carry any one of the 20 different side chain R groups .

1. What is NOT true about primary protein structures?
A. the core of the primary structure is a repeating three atom repeating unit
B. the core unit consists of amino nitrogen, carbonyl carbon, alpha carbon
C. because of steric hinderance certain amino acid sequences cannot occur
D. the amino nitrogen and the carbonyl carbon come from the alpha amino and alpha carboxyl
group of amino acids
E. The alpha carbon can carry any one of the 20 different side chain R groups