Which of the following is not a distinguishing characteristic of prokaryotic cells? a) their dna is not enclosed within a membrane. b) they lack membrane-enclosed organelles. c) they have cell walls containing peptidoglycan. d) their dna is not associated with histones. e) they lack a plasma membrane.

Which statement best describes the relationship between an allele and a gene? question 1 a. an allele is a variation of a gene that can be expressed as a phenotype. b. an allele is the part of a gene that attaches to messenger rna molecules. c. an allele is a segment of a dna molecule that controls replication of a gene.