Eukaryotic Cells

There are two types of cells: Eukaryotes and Prokaryotes.

Eukaryotic cells are those that have organelles with membranes and a nucleus.

Because they are more complex, they are also considerably larger than prokaryotes.

There are lots of different organisms that have eukaryotic cells including animals, plants, protists, and even fungi.

Identifying Eukaryotes

Eukaryotic cells have organelles such as endoplasmic reticulum, mitochondria, and a nucleus.

The requirements of organelles make them larger than prokaryotes. The average size of a eukaryote is from 10-100 micrometers and the average size of a prokaryote is around 1-3 micrometers.

While most eukaryotes are part of organisms that are multi-cellular, there are some exceptions to this in single-celled protists that have eukaryotic cells.

The organelles in eukaryotes are important because they assist in carrying out the complex and detailed processes required by the cell, and each organelle is assigned a specific function.

An example of this would be in looking at the mitochondria organelle whose job is to make energy for the cell to use.

Another difference in the two types of cells is in the DNA. Prokaryotes such as bacteria have a single circular loop shape for their DNA.

Eukaryotes have DNA that is housed and protected in the nucleus organelle with arranged chromosomes.

How did Eukaryotes Come About?

Scientists that study the cells believe that eukaryotic cells evolved between 1.7-1.9 billion years ago.

They think they began without organelles or a nucleus and were eukaryotic cells. The theory is that some of these cells consumed or “ate” the other cells and as they learned to survive together, the cells inside eventually became organelles.

This development theory is called the endosymbiotic hypothesis. “Symbiotic” means a survival that lives with and depends on each other.

As time passed, the evolution of the original eukaryotes allowed them to move into smaller groups and become plants, animals, fungi, and protest cells.

They are all different and have totally unique features, but all are eukaryotic cells.

Eukaryotic cells are far more advanced

The complex nature of eukaryotic cells includes the fact that they have the ability to accomplish many tasks.

This is due to an organized nucleus with a nuclear envelope that is kind of the “brain” of the cell.

They have DNA that is protected as well as the many organelles that can work together to be a self-sufficient organism.

There is a lot going on in the eukaryotic cell. Having organized DNA and organelles gives them to power to create their own parts.

An example of this is the tail-like structure that they have called the “flagellum”. This gives them movement.

They also create small hairs called “cilia” that allow the cell to scoot around through fluids. Other eukaryotic cells such as those called “nematocysts” have small harpoons that they use to catch prey.

Facts about Eukaryotes

  • A eukaryote can be single-celled or multicellular (such as a cat or human)
  • Eukaryote is a combination of two Greek words: eu (which means “true”) and karyon (which is a kind of kernel or nut). The translation means “true nucleus.”
  • Humans are eukaryotes and so are fungi.
  • Eukaryotes have organelles and they are therefore the only organisms that also have cytoplasm for their organelles (with the exception of the nucleus)
  • Some eukaryotes have tails that are called flagella that are made up of microtubules.
  • Eukaryotic cells can be small or large, but are always bigger than prokaryotic cells.

 Interesting Facts about Biology

  • Most viruses contain DNA, however when a virus only contains RNA, it is called a “retrovirus.”
  • Although they are still trying, mankind has not succeeded in making any manmade material that has the strength and lightness of bones.
  • Your body requires calcium to function. When it is low on calcium it will take it from your bones.
  • You have some organs in your body that are called “hollow organs.” They are called this because they have a pouch or empty tube. A few examples of these would be your intestines, heart, and stomach.
  • There are some viruses that attack and kill bacteria.
  • The discovery of the first human virus was in 1901. It was the yellow fever virus and was discovered by Walter Reed.

Eukaryotic Cells Quiz

Now let's test what you have learned!