Final answer:
The genes encoding proteins are mainly found in unique-sequence DNA in eukaryotic organisms, as these sequences contain the specific functions necessary for the cell's working and are crucial to its protein production.
Step-by-step explanation:
Eukaryotic DNA is composed of different levels of redundancy, with unique-sequence DNA, moderately repetitive DNA, and highly repetitive DNA. The genes that encode proteins are predominantly found in unique-sequence DNA. This is because unique-sequence DNA contains the sequences that are specific to the particular functions of proteins necessary for the cell's functioning, and these sequences are not typically repeated extensively throughout the genome. On the other hand, moderately and highly repetitive DNA consists of sequences that are repeated many times in the genome and usually serve structural or regulatory functions rather than encoding proteins.
The organization of genetic material in eukaryotic cells is into chromosomes, each potentially containing thousands of genes. These genes exist in a complex with histone proteins to form chromatin, which ensures efficient packaging of the genetic material within the cell nucleus. Furthermore, the discovery that a significant portion of the eukaryotic genome consists of repetitive DNA was a surprise to scientists because it showed that the genome is not solely devoted to protein-coding genes but has a vast array of elements, like transposons, which can make up a substantial portion of the genome.