Oxygen.
Oxygen was fatal when organisms started using photosynthesis, this event was known as the Great Oxidation Event.
Answer:
Humans have nearly 30,000 genes that determine traits from eye color to risk for hereditary diseases. Those genes sit along six feet of DNA, which are organized into chromosomes and stuffed into each and every human cell. Chromosomes are coiled into loops and then organized into many large domains called topologically associating domains (TADs).
Explanation:
