DNA sequences can act as "tape measures of evolution." Some highly-conserved regions of the human genome (similar to comparable
regions in other species) don't code for proteins. Why? 1. Such regions coded for proteins in genomes of distant human ancestors, but over time they became noncoding; however, conserving their sequence remained unchanged.
2. Such regions play a significant role in gene regulation. That is why they remain conservative under the influence of natural selection.
3. Such regions are the sites of DNA recombination. They should remain conservative to provide an accurate recombination process during cell division.
4. Such regions remain conservative because the mutation rate differs along the genome. In other words, such regions remain conservative accidentally.
2. Such regions play a significant role in gene regulation. That is why they remain conservative under the influence of natural selection.
Explanation:
Within the genome there are many non-coding regions that control the expression of master developmental genes such as, for example, Hox major transcription factors (TFs) in animals and MADS-box TFs in plants. These gene regulatory regions (e.g., promoters and enhancers) are generally evolutionarily conserved within certain taxonomic groups. In consequence, such non-coding regions are well known to be conserved and interact in a sequence-specific manner with major transcription factors in order to regulate developmental pathways.
The scientist think that the thinning of the ozone layer might be related to CFC because of the inverse relationship between the two which have been discovered. It has been discovered that as the amount of CFC increases, the level of ozone usually decreases.<span />
