Final answer:
Exons are the segments of DNA that code for proteins, while introns are noncoding segments that are spliced out of RNA before it is translated into a protein.
Step-by-step explanation:
The question asks which of the following types of genomic DNA codes for proteins: transposons, introns, exons, or intergenic regions. In eukaryotic cells, genomic DNA consists of both coding and noncoding sequences. The exons are the segments of DNA that actually code for proteins. During the process known as gene expression, DNA is first transcribed into RNA.
However, not all of the RNA is used to make proteins. The initial transcript includes both exons and introns. Introns are noncoding segments that are removed or spliced out of the pre-messenger RNA (pre-mRNA) to form mature mRNA, which contains only the exons. This mature mRNA is then translated into a protein. Thus, introns, transposons, and intergenic regions do not directly code for proteins; instead, exons are the DNA sequences that ultimately define the amino acid sequence of proteins.