In our previous article on cell facts, we said that we are just getting started and… we were honest! There is so much to write about cells that just a couple of articles will not do. So, expect a number of these articles summing down various facts about cells (both animal and plant cells). We are pretty sure that you are going to love these facts. So, let’s get started with our second installment.
Amazing Cell Facts: 1-5
1. In our previous article we learned about Prokaryotes and Eukaryotes. We also said that Prokaryotes do not have true nucleus while Eukaryotes have true nucleus. However, that’s not the only different. Prokaryotes do not have organelles while Eukaryotes have organelles.
2. Wondering what organelles are? Well, just like our body has organs such as heart, lungs, kidneys, liver etc. that perform some special functions, the cells also have some organs (at cellular level of course). These cellular organs are also designed to perform specific functions. These cellular organs are called organelles.
3. The most important feature of organelles is that they are bound by membranes . If something is inside the cell and is not bound by membranes, it cannot be classified as organelle.
4. Talking of Cell Membrane, both Prokaryotic and Eukaryotic cells have Cell Membrane or Plasma Membrane. In fact, they are same in both types of cells with a few exceptions of course.
5. The job of the Plasma Membrane is to ensure that the cell components (that is, the things that are present inside the cell) are held together. Also, the Plasma Membrane or the Cell Membrane is responsible for substance passage in and out of the cell.
Amazing Cell Facts: 6-10
6. Inside the Cell Membrane or the Plasma Membrane, you can find what is known as Cytoplasm. This Cytoplasm is present in both Eukaryotes and Prokaryotes.
7. The organelles that are present in Eukaryotes are embedded in the Cytoplasm. Since Prokaryotes don’t have any organelles, you won’t find any organelle embedded in the Cytoplasm of the Prokaryotes.
8. Inside both Eukaryotes and Prokaryotes, you will find something called Ribosomes. These Ribosomes are not organelles because they do not satisfy the necessary condition – that is, they are not bound by membranes.
9. These Ribosomes are actually sites of protein production inside the cells. Proteins are actually extremely important because they are needed not only for the functioning of the cells but also for the structure of the cells.
10. When you put a cell under a microscope, you will see various things. In case you put a plant cell under a microscope, you will see what is known as Cell Wall. This Cell Wall is absent in case of animals (including humans).
Amazing Cell Facts: 11-15
11. Exact location of the Cell Wall? It is an extra layer right over the Cell Membrane or the Plasma Membrane. It is tougher than the Cell Membrane. This Cell Wall can also be found in bacteria, which are basically Prokaryotic cells.
12. Again, under the microscope, you may notice that some cells have small projections over the surface of the cells. These projections are on the outside and not inside. The purpose of these small projections is to allow movement. These small projections are referred to as Cilia.
13. Inside the cells, as we said before, is the Cytoplasm. This Cytoplasm is semifluid substance and always invariably remains closed by the Cell Membrane or the Plasma Membrane.
14. Then there is something interesting inside the cells. There is a network of tiny filaments. The purpose of these filaments is to ensure that the cell maintains its shape and they (filaments) also ensure that the organization of components inside the cells are maintained. These filaments also help cells with movement and even cell division. These tiny filaments’ structure is known as the Cytoskeleton.
15. And then there is Endoplasmic Reticulum, which too is an organelle. It is present in most of the Eukaryotic cells and it is the largest organelle inside a cell. It extends all the way from the Plasma Membrane or the Cell Membrane all the way up to the Nuclear Envelope. It is embedded in the Cytoplasm.
Amazing Cell Facts: 16-20
16. The Endoplasmic Reticulum (usually referred to as ER) is not present in Prokaryotic cells because as we mentioned earlier, organelles are absent in Prokaryotic cells.
17. The Endoplasmic Reticulum is a continuous network of flattened sacs and tubules, which are enclosed in membranes. The ER has a number of functions and it actually makes up more than 50% of membranous substances that are found inside a cell.
18. The ER has two distinct parts – the Smooth Endoplasmic Reticulum and the Rough Endoplasmic Reticulum. The tubules network form the Smooth ER part while the flattened sacs form the Rough ER part.
19. Why smooth and rough? The Rough part is basically where Ribosomes are attached on the membrane of ER on the side facing the Cytoplasm. These attached Ribosomes give it a rough appearance. The Smooth part is basically where no Ribosomes are attached and hence, doesn’t have a rough appearance.
20. The space inside the Endoplasmic Reticulum is known as the Lumen. Now, ER is connected to the Nuclear Envelope and hence, there has to be space inside the Nuclear Envelope. This space inside the Nuclear Envelope and the Lumen together form the part of the same compartment.