Cells are the basic building blocks of life, they are what make up organisms.
All biological lifeforms are made up of cells.
A single cell can actually be an entire organism by itself, such in the case of bacteria. Single-celled organisms though, have what are known has prokaryotic cells, which unlike their eukaryote counterparts, do not have a nucleus. We’ll look at this in more detail further down.
But often cells create other cells in order to build multi-cellular organisms together. Different cells will then learn how to perform different functions, depending on how complex the organism is.
You’ll often see cells split into two main categories when studying biology: Animal cells – which include human cells – and plant cells.
Let’s look first at the basic structure of a animal cell below:
Cell Nucleus – Often described as the command centre or brain of the cell. The nucleus is where you find your genetic information, and is also where growth and reproduction of the cell is controlled.
Mitochondria – Known as the powerhouse or battery of the cell. This is an organelle within the cell and is the only other place, besides the nucleus, where you find DNA within a human/animal cell. Mitochondria contain many enzymes, including those responsible for the conversion of food and nutrients into usable energy.
Cytoplasm – This is where all the organelle, including the nucleus and mitochondria sit. The cytoplasm is a semi fluid area of the cell and is made up of water, proteins and salts.
Cell Membrane – This is what separates the inside of the cell itself from the outside environment. It is often called the plasma membrane and is made of lipids and proteins and surrounds the cytoplasm.
Comparison to a plant cell
What do we find in a plant cell that we do not find in a human/animal cell?
Cell wall – As you might guess from the name, this is an outer structure of the cell, providing extra support and protection.
Chloroplasts – These are the food producers of the cell. A chloroplast’s job is to convert light energy from the sun into usable sugar for the cell. This process is called photosynthesis, which we can learn more about later.
Also remember these are eukaryote cells that we are looking at above. Below is an example image of a bacteria, which is a single-celled organism. This is a prokaryote cell, with one of the main differences being you find the DNA loose in the cytoplasm, as opposed to being within the nucleus like we see with the animal and plant cells above.
How nature changes, but doesn’t change.
Interestingly, when we look at different levels of nature in this physical universe, we can see similarities in structure, even if what we are looking at is manifesting in different ways. If you have already studied our section on chemistry or physics, you may have noticed the following comparison.
Let’s look below at a diagram of three things: The Cell, The Atom, and the Solar system.
As we can see they all have a very similar structure. A nucleus or a central body, which is surrounded or orbited by other elements within the composition. One could even compare this design to the planet, with the planets core being in place of the nucleus, or even the human body, containing the solar plexus.
