What makes us so complex? How are we any different from simple single-celled bacteria? It’s because we’re further up the evolutionary chain; we’re examples of eukaryotes.
In this lesson, we’ll define Eukarya and eukaryotes and explore their characteristics.
In science we’ve developed a way to keep organized. In biology, specifically, we have a method called biological taxonomy. There are eight rankings to help us keep living things organized. These ranks, in order of most general to most specific, are Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
An easy way to remember this is to take the first letter from each rank, and we get the following: Did King Phillip Come Over For Great Spaghetti?In this lesson, we’ll discuss the first rank, domain, in regards to Eukarya. At this point, domain is still somewhat controversial and not fully recognized, but it is generally accepted by the scientific community. As students and scientists, we recognize the idea of the domain as very real and similarly need to understand it.
What Are Eukarya?
Eukarya includes eukaryotic organisms. These are organisms with cells that contain a nucleus as well as membrane-bound organelles. The kingdoms most associated with Eukarya are the Plantae, Animalia, and Fungi kingdoms.
Additionally, Kingdom Protista has had some of its organisms, such as amoebas and some seaweeds, classified as Eukarya.We, as humans, are classified as Eukarya. All of our own cells have a nucleus and membrane-bound organelles. In fact, all complex organisms are eukaryotic.
There is just no real way for prokaryotic organisms to grow into the complexity that eukaryotes have.
Where They Came From
Eukarya represent only a small amount of living organisms, with prokaryotes outnumbering them by a large margin. Organisms in the Eukarya domain split through mitosis (cell division) and reproduce through meiosis (sexual reproduction where male and female gametes combine). Eukarya is a rather ‘young’ domain because eukaryotes only came about around 1.
7 billion years ago. If we recall that the earth is roughly 4.6 billion years old, 1.
7 seems rather young. The first prokaryotes, for example, showed up around 3.8 billion years ago.Our own eukaryotic cells arose when prokaryotic cells began this process called infolding. These membranes then grew out eventually pinching off to form most of the organelles that we see today. These organelles could not be digested, and as a result, they now are commonplace inside of the cell, and each carry out specific roles.
It is also the result of these organelles forming and evolving inside of our cells that we are able to live as we do. Human beings along with other organisms are some of the most complex and amazing creatures in the history of Earth. All due in part to our eukaryotic cells.
- Domains arose from the need to classify and organize living organisms better.
- Eukarya is a domain.
- Eukarya are eukaryotes, containing membrane-bound nuclei and organelles.
- Eukaryotes are younger, fewer, and more complex than prokaryotes.
- Eukarya evolved around 1.7 billion years ago.
- The membrane-bound nuclei and organelles evolved through the process of infolding, in which the prokaryote membranes folded on themselves and pinched off, leading to the formation of these organelles.