試題詳解

35. Which of the flowing descriptions about gene structure and chromosomal organization are CORRECT?
(A) A gene is the entire DNA sequence required for synthesis of a functional protein or RNA molecule, including coding region, control region and intron.
(B) Many genes encode functional RNAs that are not translated into proteins but perform significant functions, such as rRNA, tRAN, and snRNAs. Among these are the exception micro RNAs (miRNAs), although up to 1000 in humans, have no any biological significance.
(C) Although DNA transposons occur in eukaryotes, retrotransposons generally are much more abundant in vertebrates.
(D) Each eukaryotic chromosome contains a single DNA molecular packaged into nucleosomes and folded into a 30-nm chromatin fiber.
(E) In eukaryotic cells, the organization of DNA into chromatin allows a mechanism for regulation of gene expression.