Eukaryotic Cells: Inception of Complex Life

What Makes Eukaryotic Cells Different

In order for the production of specific proteins, evolution had to create multiple systems that were previously not present in any life form. One of the most visible differences that developed was the presence of enclosed structures within cells known as organelles. These organelles allowed the cell to tackle many issues that otherwise were impossible to address.

The Utility of Organelles

Because organelles allowed for cells to send products to specific places, they became an essential component of complex life. For example, without certain organelles, it would be impossible for cells to choose which phospholipids (fat molecules used by cells) or proteins were incorporated in its membrane. The type of phospholipids displayed on the membrane are important in inter-cellular communication. It is easy to understand its importance.

Moreover, this compartmentalization of tasks allows cells to perform tasks faster and more efficiently than if every molecule was randomly floating around in the cell. Segregating tasks allow for optimal use of enzymes since the molecules they need are always nearby. These new systems revolutionized the ability of cells to use energy and create unique products. This is a lot like the Industrial Revolution for life on Earth. In order to compensate for the added volume of material, eukaryotic cells are much larger than the simpler prokaryotes.

The Nucleus

The next important characteristic that evolved in eukaryotic cells is actually an organelle that is so important that it always gets its own mention: the nucleus. In fact, eukaryote translates directly from Latin to “true nucleus”. The nucleus is like the brain of the cell. This is because the nucleus is where the DNA is contained. Because DNA is the reason the cell exists, it has designed the nucleus to acts as a protective barrier. Access to the nucleus is nearly impossible for molecules that do not belong there. The mechanism involved in nuclear regulation is very complicated and deserves its own post.

Ideally, the nuclear pores only allow molecules involved in processes involving genetic replication and protein formation into the nucleus. This is important because anything that interacts with DNA has the potential to destroy the delicate complexity holding a cell together. An interesting case that illustrates the fragility of DNA is radiation poisoning.

The Mechanisms of Radiation Poisoning

Exposure to radiation causes people to get sick, bleed a lot, and die. However, once you begin to ask why, the story becomes more interesting. For this example, we will focus on the type of radiation known as alpha radiation. When a radioactive atom begins to decay, it releases packages made of 2 protons and 2 neutrons. These small particles are launched out at incredibly high speeds.

When a person is near such a radioactive source, these particles hurtle towards them and go right through, exactly like a bullet. As the projectile pierces through the body, it destroys whatever chemical bonds are in its way, tearing through the nucleus of countless cells and the bonds holding DNA together. Cells in the body are left without instructions on how to function. This results in massive cell death, leading to bleeding as blood vessels rupture. In addition, surviving cells may still have taken damage, resulting in dysfunctional units, most commonly associated with cancer.

Sunburns and DNA

Another short example of nuclear damage is sunburn. Ultraviolet light has the ability to chemically change the shape of DNA, making in very difficult to read. Usually, melanin acts as a shield for DNA, forming a coat around the nucleus. When melanin is not present, the UV rays damage the living skin cells under the surface layers. This results in the inability for these cells to divide and leads to painful peeling. This peeling is the way the body removes potentially dangerous skin cells that have been damaged too significantly.