Answer:
TEs are repetitive and mobile elements, thereby it is hard to trace their origins
Explanation:
Repetitive elements are patterns of nucleotide sequences in the DNA characterized to have multiple copies throughout the genome. DNA mini-satellite and Transposable Elements (TEs) are some examples of highly repetitive DNA. TEs are repetitive mobile elements that have the ability to jump within the genome and occupy a major part of eukaryotic genomes. For instance, there is a type of TEs called retrotransposons which mobilize through a copy-and-paste mechanism, thus increasing their number in a genome. In consequence, TEs represent highly repetitive and dynamic genomic sequences, and thereby it is hard to trace their evolutionary histories.
Answer:
Bacteria cells have no nucleus.
