Introduction to Cytoplasm
Every student who has studied biology in their life knows how crucial the cell is for the continuity of life on Earth. There is a reason why it’s known as the building block of all life in this universe that we live in. The subject of Cytology, which is the study of cells, informs us that a cell is formed as a result of the amalgamation of multiple organelles and other building blocks that reside inside the cell. But the question is; what is cytoplasm?
What is Cytoplasm?
In Biology, we can define it as a semifluid material that resides inside the cell and is surrounded by the walls of the cell known as the cell membrane. The cytoplasm has numerous cytoplasmic components including mitochondria, cytoplasmic structures, cytosol, and so many organelles.
Now the question remains of its location, where is it located? Where can we find the cytoplasm in the body? You can find the cytoplasm inside the cell, however, its location can vary based on what kind of cell it is.
- For a eukaryotic cell (which includes an animal cell and a plant cell), you can locate the cytoplasm enclosed in between the nuclear envelope (of the nucleus) and the cell membrane (of the cell).
- For a prokaryotic cell (which includes the bacterial cell) the cytoplasm can be found inside the cell everywhere because a prokaryotic cell lacks a well-defined nucleus so the cytoplasm is just surrounded by a cell membrane.
Another interesting question to ask yourself is do all cells contain a cytoplasm to hold the organelles? Yes, every cell possesses a cytoplasm but the size of it can vary. The size of the cytoplasm is different from one cell to another. Let’s look at an example of the sperm cell and the egg cell to understand this better:
For instance, let us consider a sperm cell that loses most of its cytoplasmic organelles and only possesses very little cytoplasm in its head. It also has a super compact nucleus so it can achieve a more streamlined structure that helps with motility.
On the other hand, if you look at the egg cell (the ovum) it has a large cell because it has a large cytoplasm. The ovum is also considered the largest cell present in the human body as it is a whopping 10,000 times bigger than a typical sperm cell. There is a reason for its big size as well; it has to store a large number of nutrients so it can support life in case it gets fertilized and as a result, a zygote is formed from it.
What Are The Components of The Cytoplasm?
The components of a cytoplasm vary based on the type of cell. For example, in the case of a prokaryotic cell (for instance, archaeans and bacteria) a membrane-bound nucleus is absent. As a result, the cytoplasm stores all the components of a typical prokaryotic cell inside the plasma membrane.
However, when we look at a eukaryotic cell (animal cell and plant cell) there are three main components of the cytoplasm. They are called organelles, cytosol, and cytoplasmic inclusions (various granules and particles). Let’s take a look at the above-mentioned components in detail:
Cytosol
The cytosol can be defined as the liquid medium or a semi-fluid component of a eukaryotic cell that is present inside the cell membrane but outside the nucleus.
Organelles
Organelles can be defined as small cellular structures tasked to perform specific functions inside a eukaryotic cell. Some examples of organelles include lysosomes, Golgi Apparatus, mitochondria, endoplasmic reticulum, ribosomes, chloroplasts, and nucleus. A cytoplasm also contains a cytoskeleton.
What is a Cytoskeleton?
It is a network of fibers whose function is to provide support to the organelles present inside the cell and help the cell keep its shape.
Cytoplasmic Inclusions
Cytoplasmic inclusions can be defined as numerous particles temporarily suspended inside the cytoplasm and they normally consist of granules and macromolecules. There are three types of inclusions that are present inside the cytoplasm. They are called pigment granules, secretory inclusions, and nutritive inclusions. Some common examples of secretory inclusions are acids, proteins, and enzymes. The nutritive inclusions include lipids and glycogen (glucose storage molecule). The most common example of a pigment granule is the melanin that is found in our skin cells.
What is The Physical Nature of The Cytoplasm?
It is still a bit unclear how the numerous components of the cytoplasm come together to perform the function of the movement of organelles without disrupting the structure of the cell in any way or form. However, their flow is, nonetheless, very important for the various cellular functions happening inside the cell that depend directly on how permeable the cytoplasm is. Let’s study an example of a cellular function to understand this in a better way:
For instance, let’s consider cell signaling. Cell signaling is a process inside the cell that relies on the process with which the signaling molecules are allowed to diffuse across the cell and in that case their size matters too. So, a small signaling molecule such as a calcium ion is able to perform the diffusion without any difficulty. A large molecule and other subcellular structures, on the other hand, often need some sort of help to move through the cytoplasm. This type of irregular dynamics and shapes of such particles are responsible for giving rise to the different theories you read about the nature of the cytoplasm.
Does The Cytoplasm Behave Like A Sol-Gel?
This is an interesting theory because the cytoplasm has been considered to behave like a sol-gel, thanks to the plenty of evidence pointing to its behavior. It is thought that the structures and the component molecules present inside the cytoplasm behave like a disordered colloidal solution (sol) at times and they also behave like an integrated network, creating a solid mass (gel) at other times.
This theory, therefore, puts forth the possibility that the cytoplasm behaves like solids and distinct fluids at times based on the level of interaction that occurs between cytoplasmic components. This also explains the clearly different dynamics of the numerous particles that can be seen performing different movements through the cytoplasm.
Let’s Talk About Cytoplasm Function
The cytoplasm no matter what cell it is a part of (be it a eukaryotic cell or a prokaryotic cell) has to perform certain functions. Growth, metabolism, and cell expansion are some kinds of functions that are carried out inside the cytoplasm. Not just that, the cytoplasm is also home to a number of chemical reactions. Cellular metabolism is one such example of the chemical reactions happening inside the cytoplasm because the cytoplasm acts as a bridge between most of the organelles, present inside the cell, and the cell membrane.
However, the cytoplasm has a lot more functions than just that. Here are many other functions of the structure of the cell under discussion, including:
1. Protection
- The cytoplasm protects the cell and all of its components from getting damaged in any way or form.
- It also keeps the cell in its supposed shape and manages to keep the organelles in their place to help the cell with its defense strategies.
- Plus, the cytoplasm acts as a shock-absorber more than often, especially when the cell is attacked (the cytoplasm cushions any blow that the cell faces).
2. Structure & Support
- The cytoplasm helps the cell with its turbidity and structure by helping it keep its shape as it is extremely crucial for the correct arrangement of cells.
- The fact that the cytoplasm keeps the membrane-bound organelles in their place also keeps them from making any unnecessary movements.
- Storage
- The cytoplasm is home to many enzymes and storage units that are required for important metabolic activities.
- In the case of a plant cell, the cytoplasm stores storage units that store the excess glucose produced in photosynthesis.
3. Transport
- The cytoplasm also helps with the transportation of cytoplasmic inclusions and the organelles all over the cell by using a procedure known as cytoplasmic streaming.
- It also moves out any waste material out of the cell to keep it clean and safe.
Cytosol vs Cytoplasm
The cytosol and cytoplasm are two separate components of a cell. Cytosol is an intracellular fluid found in the cytoplasm and the cytoplasm is what we’ve just studied in detail. Still, both structures are constantly confused together.
In short, the cytosol is present inside the cytoplasm, while the cytoplasm is all the material within the cell membrane.
Conclusion
The cytoplasm is very important to the function of life. In fact, if our cells had no cytoplasm in them, they would stop functioning and life, as we know it, would cease to exist. It performs a variety of functions just to keep us alive. If you want to know more about cytoplasm and what it does, consult a biology tutor for a detailed session.
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