Final answer:
Nonfunctional copies of normal genes important in estimating evolutionary ages of phylogenetic relationships are known as pseudogenes. Even though pseudogenes are often categorized as junk DNA, they are valuable in evolutionary biology for understanding phylogenetic relationships and evolution.
Step-by-step explanation:
Nonfunctional copies of normal genes, which lack both introns and promoters, and are important in estimating evolutionary ages of phylogenetic relationships, are referred to as pseudogenes.
Pseudogenes arise from gene duplication or retrotransposition events and have lost their ability to encode protein or be expressed by the cell.
They are considered part of what was once labeled junk DNA, a term that has fallen out of favor as researchers uncover functional roles for various noncoding DNA sequences. Initially thought to be functionless, pseudogenes can contribute to our understanding of evolutionary processes and phylogenetic relationships.
The accumulation of mutations in these sequences can act as a molecular clock and help estimate the time since two species have diverged.
Some pseudogenes are processed, meaning they are reverse transcribed from mRNA and inserted back into the genome without intronic sequences.
These sequences can serve as important genetic markers in evolutionary studies. Although pseudogenes do not encode functional proteins, their presence and variation are valuable tools for evolutionary biologists to trace phylogenetic relationships and understand the molecular basis of evolution.