Eukaryotes

What is a eukaryote? The simple answer is anything living thing that can is not capable of asexual (mitosis) reproduction or simply a life form that needs to have sex to reproduce (plant pollination is a simple form of sex). Eukaryote life forms include algae, protozoa, slime molds, plants, and animals including us humans. Eukaryotes appeared about a billion years ago, not long after oxygen had been introduced in the atmosphere. Why? At first the early Earth's only oxygen was in water. The first life forms, maybe like the ones which live in the hot springs of Yellowstone National Park, ate hydrogen out of the atmosphere and the primordial soup (pools of organic chemicals, probably where life originally began). Eventually, all that hydrogen had been depleted, so they moved to deep sea hydrothermal vents. That worked well, as the tops of the Earth's oceans were frozen over, two and a half billion years ago. Eventually most of that hydrogen had been depleted too. So they started extracting it out of the water. Soon copious amounts of oxygen were being released into the air. This oxygen killed most of the early life forms, causing a massive famine. Bacteria were dying everywhere. But quite by accident, one day, a bacteria ate a complex organic structure known as a mitochondrion. The mitochronion helped that bacteria breath the oxygen and even process it into food. Over millions of years, these bacteria evolved to have different sexes. Thus the very first eukaryote was born.  The first eukaryotes probably were single-celled, such as algae, protozoa, and Euglena, which lived at the top of the ocean. There are several more differences between prokaryotes and eukaryotes. Notably that prokaryotes have no cytoplasm, cell membrane, or nucleus (although prokaryotes still have DNA).