We have prepared an informative article that can teach you all that you need to learn about cells so that you can put your digital dissecting microscopes to good use. You can also take a quick look at some of the other articles we have available and learn more about compound microscopes with camera and many other instruments.
What is a cell and what is it made of?
According to the British Society for Cell Biology, a cell is the basic unit of life as we know it, namely the smallest unit that is capable of reproducing independently. The name “cell” is older than you might imagine, as it was first suggested by Robert Hooke back in 1665 and it comes from the Latin ‘cella’ which means chamber or storeroom.
He came up with this name after he used a very early version of a microscope to look at a piece of cork. All living things, be them animal or plants are made of these building blocks. When they work in concert with one another they can create complex living things such as animals and humans, which are multicellular organisms.
No matter the type of organism, be it multicellular or unicellular, cells are very small and impossible to see without an optical microscope. While cells share many common features, they look very different depending on the roles they play.
Take for example nerve cells – they have long and thin extensions that can reach for meters in order to transmit signals as quickly as possible. On the other hand, brick-shaped plant cells have a rigid outer layer that provides the structural support that plants such as trees require.
If you are wondering about the composition of these building blocks, in the case of a human cell, two-thirds of it is water. The rest of the cell is a mixture of lipids, proteins, carbohydrates, enzymes, and other molecules.
If you are looking to find even more about the structure of a cell, we will explore the main components of a cell, such as the membrane, cell wall and nucleus, together with some of the other lesser-known components below.
Cell membrane and cytoplasm
The cell membrane, also known as the plasma membrane, is a structure that separates the space inside the cell from the outside of it. Both plant and animal cells have this component which surrounds and protect the cytoplasm.
The cytoplasm is a gel-like fluid inside the cell and it is the medium for chemical reactions. The functions for cell expansion, replication and growth are done in this structure of the cell. Inside the cytoplasm, materials move by a process known as diffusion.
Now back to the cell membrane, this structure is composed of a double layer of special lipids that are called phospholipids. They prevent water-loving (hydrophilic) substances from entering or escaping the cells. Furthermore, the cell membrane is also studded with proteins which serve various functions.
Some of the proteins can determine what substances are allowed and not allowed to cross the membrane, while others function as simple markers to help identify the cell as part of the same organism or to identify it as foreign. Some also serve the role of communicators by sending and then receiving signals from any neighboring cells and the environment.
The cell wall is a non-living and rigid layer that is found on the outside of the cell membrane and that surrounds the cell entirely. Plants, fungi, and bacteria all have cell walls and in plants, the wall is composed of cellulose. In the case of humans and animals, their cells do not have a cell wall, just cell membranes.
The main function of a cell wall is to form a framework that can prevent over expansions. Other roles include providing mechanical strength and support to control the direction of cell growth, help regulate growth and diffusion, and help the cells communicate with one another via the channels found between plant cell walls.
Nucleus and nucleolus
The nucleus is the control center and there you can find the deoxyribonucleic acid (the famous DNA), which is the genetic material of the cell. There is also the nucleolus, a region found in the nucleus that is dense in ribonucleic acid (RNA). The nucleus is the brain of the cell, so to speak, and it will determine how the cell will eat, move, function and reproduce.
Despite its name, the nucleus is not always in the center of the cell. It can be easily observed as a big dark spot found somewhere in the middle of the cytoplasm. You can’t find it near the edge of a cell since it would be too dangerous of a place for it to reside.
Even if the nucleus is an important part of a cell, not all will have one. If a cell does not have a defined nucleus, the DNA will most likely be found floating around the cell in a region known as the nucleoid. In this sense, cells are categorized into eukaryotic (that have a defined nucleus) and prokaryotic (that don’t have a defined nucleus).
What other components are there?
We briefly mentioned DNA and RNA – these are nucleic acids that help express the genetic code of the cell. DNA contains all the information needed to build and maintain the cell, while RNA acts as a messenger and carries instructions from the DNA.
While nucleic acids are very important, they are not the only ones responsible for the expression and preservation of genetic material and that’s why special proteins called enzymes are used. With the help of proteins, the cell can replicate the genome and accomplish cell division.
Carbohydrates are another type of organic molecules. They are classified into simple and complex carbohydrates, and the former are used for the cell’s immediate energy demands while the latter serve as intracellular energy stores.
Finally, the lipids or the fat molecules are the components of the cell membranes and other structures that are involved in energy storage, and they help relay signals to a cell’s interior.