【多选题】There are several important differences between genomic DNA clones and cDNA clones. What are the differences?
A.
Genomic clones represent a random sample of all of the DNA sequences found in an organism’s genome and, with very rare exceptions, will contain the same sequences regardless of the cell type from which the DNA came.
B.
Also, genomic clones from eukaryotes contain large amounts of noncoding DNA, repetitive DNA sequences, introns, regulatory DNA, and spacer DNA; sequences that code for proteins will make up only a few percent of the library.
C.
By contrast, cDNA clones contain predominantly protein-coding sequences, and only those sequences that have been transcribed into mRNA in the cells from which the cDNA was made.
D.
As different types of cells produce distinct sets of mRNA molecules, each yields a different cDNA library. Furthermore, patterns of gene expression change during development, so cells at different stages in their development will also yield different cDNA libraries. Thus, cDNAs can be used to assess which genes are expressed in specific cells, at particular times in development, or under a particular set of conditions.