Lokiarchaeota facts for kids

The Lokiarchaeota are a special group of tiny living things, so small you need a microscope to see them! They are a type of Archaea, which are like very old, simple forms of life. Scientists first found out about them in 2015 when they studied their genome. A genome is like a complete instruction book for how a living thing is built and how it works.

What is Lokiarchaeota?

Lokiarchaeota are part of a larger group called Archaea. Archaea are one of the main types of life on Earth, along with Bacteria and Eukaryotes. Eukaryotes are living things with complex cells, like animals, plants, fungi, and protists. Lokiarchaeota are very interesting because they seem to be a "missing link" between simple life forms (Archaea and Bacteria) and more complex life forms (Eukaryotes).

The Lokiarchaeota Genome

Scientists studied the full instruction book, or genome, of a Lokiarchaeota called Lokiarchaeum. They found it has over 5,000 different genes that make proteins. Proteins are like tiny machines that do most of the work inside cells.

What the Genes Tell Us

When scientists looked closely at these genes, they found some surprising things:

• About one-third of the genes were completely new and didn't match anything known before.
• Many genes (about 26%) were similar to genes found in other Archaea.
• A good number of genes (about 29%) were similar to genes found in Bacteria. This shows that genes can move between different types of tiny life forms.

Genes Like Ours

The most exciting discovery was that a small but important part of Lokiarchaeota's genes (about 3.3%) were very similar to genes found in Eukaryotes. Eukaryotes are living things with complex cells, like humans, animals, and plants.

These "eukaryotic-like" genes in Lokiarchaeota are important for things like:

• Building the cell's outer skin, called the cell membrane.
• Making the cell's internal "skeleton," called the cytoskeleton. This skeleton helps the cell keep its shape and move things around inside.

One special protein found in Lokiarchaeota, called actin, is also found in eukaryotes. In eukaryotes, actin helps cells move and change shape. It's also key for a process called phagocytosis.

How Cells Eat: Phagocytosis

Imagine a cell "eating" another tiny particle or even another cell. That's phagocytosis! The cell uses its outer membrane and internal skeleton (with proteins like actin) to wrap around and swallow the particle.

This ability to "eat" other cells is super important for how complex life might have started. Scientists believe that our cells, and the cells of all animals, plants, and fungi, got their mitochondria this way. Mitochondria are like the powerhouses of our cells. The idea is that a long, long time ago, an ancient cell "ate" a bacterium, and instead of digesting it, they started living together. This is called endosymbiosis. The bacterium became the mitochondria inside the larger cell.

Lokiarchaeota having genes for phagocytosis suggests they might be able to "eat" other tiny things. This makes them a very interesting clue in understanding how simple cells evolved into the complex cells that make up all larger living things today.

Images for kids

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  Candidatus Prometheoarchaeum syntrophicum. (c) SEM of a dividing cell. Scale bar = 1 μm. (d) Cryo-EM of a single cell. Scale bar = 500 μm. White arrows indicate large membrane vesicles.

See also

In Spanish: Lokiarchaeota para niños