Every living organism amounts to nothing but a collection of cells working to sustain the whole. Some of them make blood and bone, and some of them convert sunlight to chemical energy - all remarkable phenomena, in themselves. Whether plant or animal, the cells' functions and many of the structures remain the same. Here, we explore cell biology: how cells function, how they're built, and how they behave.
Cellular Biology Facts
- Animal and plant cells are eukaryotic; bacteria and archaea are prokaryotic.
- Plant cells rely on strong walls to protect them, while animal cells have much greater infrastructure to rely on.
- Whether plant or animal, eukaryotic cells have many organelles in common.
- Plants have a few organelles that animal cells don't.
Cell Biology Definition
Cell biology studies the structure, function, and behaviour of cells.
Every living organism, down to single-celled bacteria, is made up of cells. Within the cells, components ensure the cell's homeostasis (stability). Some organelles ensure proper nutrition, others 'power' the cell through protein production and yet another cleans up any waste materials.
Cellular biology studies how cells function, with an eye towards treating diseases and improving health. Cell biologists work in genetic study, cancer research, and cutting-edge biomedical exploration.
How Cell Biology Became a Discipline
Robert Hooke and Antonie van Leeuwenhoek laid the groundwork for cell study in the 17th century. However, it was only during the 1830s, when two German scientists put their heads together, that a concrete foundation for studying cells emerged.
1. Living organisms are made up of cells.
2. Cells are the basic structural unit of all organisms.
3. All cells come from pre-existing cells.
4. The cell is the basic unit of reproduction.
Once Matthias Schleiden and Theodor Schwann laid those ground rules, the study of cells began in earnest. Microscopes had been around for a while by that time, but design and lens improvements advanced in tandem with the science. The better one could study a cell, the faster competing theories about cells emerged.
Viruses, also living organisms, have no cells.
Thus, some biologists do not consider this theory universally applicable.
Nevertheless, cell theory remains foundational to the science. This theory's timeline of development shows that, rather than diminishing in importance, it grows more relevant with each new discovery.
The Structure of Cells
We find substantial differences between animal and plant cells. For one, plant cells keep their shape through internal pressure - called turgor pressure or, sometimes, hydrostatic pressure.
Also, they have a cell wall that both protects the cells and helps maintain their form. Furthermore, because they are so densely packed together, their shape tends to be more uniform, more like a square than an ovoid or circle.
By contrast, animal cells come in a variety of forms. Red blood cells are disc-like, neurones are long and stringy, and lymphocytes change shape as needed. Their shape helps them in their function. Note that animal cells are far more mobile than plant cells.
Both plant and animal cells have walls. Plant cell walls are a bit tougher and more uniform.
Animal cell walls are more like a membrane.
Besides those initial differences, plant and animal cells have many of the same inner parts - organelles, that fulfil the same functions.
| 🧩Cell component | 👷♀️What it does |
|---|---|
| Nucleus | Holds all the genetic information. |
| Mitochondria | Provides power for the cells to function. |
| Ribosomes | Creates long chains of polypeptides to synthesize proteins. |
| Endoplasmic reticulum | Forms and tags proteins. |
| The Golgi apparatus | Sends repackaged lipids and proteins out. |
| Lysosomes (animals) Vacuoles (plants) | Waste disposal |
| Cytoplasm | The gel-like substance these organelles remain suspended in |
Besides the cells' waste disposal organelles being different, plants have a couple more organelles that don't feature in animal cells. They are the chlorophyll-laden chloroplasts and the aforementioned vacuoles. Not only do they help maintain turgor pressure, but they store water, proteins and other molecules that help sustain the plant.
As mentioned above, plant cell walls are tougher than animal cell walls because they are cellulose-reinforced. Cellulose may be a difficult substance for some animals to digest, but it helps plant cells maintain their structure.
Specialised Cell Structures
Animals (mammals) are host to many types of specialised cells1. Among them, we highlight:
red blood cells
muscle cells
egg and sperm cells (haploids)
nerve cells
ciliated cells
Red blood cells, also called erythrocytes, carry oxygen throughout the body and return carbon dioxide to the lungs. Their flattened, disc-like shape offers maximum surface for gas exchange. These cells lack most organelles present in other cells, including a nucleus and mitochondria, to make room for all the gases they transport.
Muscle cells are also called myocytes, and many types power our bodies' movements. Their structure allows them to contract; their adaptation facilitates movement. They contain specialised protein filaments that, when activated, slide past one another. This action shortens the cell.
Egg and sperm are reproductive cells. They're called haploids because each contains half of the genetic information they must pass on.
Nerve cells (neurones) are communicator cells. They dwell in the nervous system and use electrical impulses to send messages. Nerve cells are equipped with dendrites; those are the signal receivers. The cells' axons relay the signals from the cell body towards target cells.
Ciliated cells can grow hair. Humans have ciliated cells around their eyes; they produce eyelashes. These cells fall in the epithelial category, as they are protective, lining cells, just as skin is. Ciliated cells exist inside the body's organs, too. For instance, in our lungs, nasal cavities, and around our spinal cord.
Cell Biology: Functions and Processes of Cells
We just threw a lot of cell names at you and gave you a very brief summary of what they do. Now, let's match their functions with the overall work that cells perform.
Maintaining Metabolism
We must eat to live, not live to eat.
Attributed to Molière
That French playwright might have been writing cells' declaration - if they had any consciousness to declare anything. In fact, maintaining the chemical processes that allow an organism to survive is the cells' prime directive. How do they do it3?
Cell metabolism is a tightly regulated system that converts energy and biosynthesises particles. This process maintains homeostasis within the cell and, more broadly, throughout the organism.
Cell Division and Reproduction
Cell division is essential for repair, growth, and reproduction. Organisms rely on this process for growth from a single-celled zygote to a fully functioning entity. Eukaryotes (plants and animals) undergo two types of divisions4:
Mitosis
- produces two daughter cells that are genetically identical
- each has the same number of chromosomes as the parent cell
- this process steers tissue repair, growth, and asexual reproduction
Meiosis
- production of four genetically diverse gametes
- each gamete is haploid (has half the number of chromosomes needed for reproduction)
- this process steers sexual reproduction
The cell cycle drives these processes. At the interphase stage, DNA replication and growth take place. During the mitotic stage, the nuclei and cytoplasm undergo division. Really, the way cells function is quite amazing.
Communication and Signalling
We all know what happens when a plan misfires or when an engine misfires; things go wrong, and the intended result doesn't materialise. Now, there's no such thing as a biological misfire, at least, not by that name. However, we can cite plenty of instances when intended results go awry biologically:
- Neural misfires cause twitching muscles, epilepsy, and migraines.
- Genetic misfires lead to mutations which, in turn, may cause debilitating conditions.
- Immune system misfires are the cause of autoimmune diseases.
These are just three examples to demonstrate why communication and signalling are crucial for cells to coordinate their activities. They do so in several ways, with these four dominating5.
Besides preventing 'misfires', cellular communication is vital for cellular and organism homeostasis. Research links communication dysregulation or dysfunction to conditions such as cancers, neurodegenerative conditions, and autoimmune disorders.
Applications of Cell Biology
Anyone living with - or caring for someone with - a neurological disorder, genetic condition, or autoimmune dysfunction knows how important research into cell biology is. However, this field of science extends far beyond managing and curing diseases.
Humans have been practising biotechnology for millennia: bread baking, cheesemaking, and brewing. This science underwent a major evolution in the 1960s. That's when genetic engineering and molecular biology became cutting-edge fields. Today, they produce life-changing medicines and interventions that improve sufferers' quality of life.
Concerns over gene editing and environmental stability.
In fact, where agricultural and environmental research are concerned, pushback grows ever fiercer. Consumers increasingly speak out against genetically modified foods, and many stand divided on matters like climate science and soil rehabilitation.
Green biotechnology has an urgent mandate to engineer drought-resistant crops that can resist pests without chemicals. And if biologists can engineer a way to enhance crop yield, food security won't be such a pressing issue.
The use of petroleum-ingesting microbes has reduced the damage caused by oil spills.
The fossil fuel industry gets a lot of hate, and for many reasons. But the bottom line is, our industrialised society doesn't yet have a suitable replacement. For now, we're more or less stuck with oil traversing the globe and, inevitably, spilling and spewing. That being the case, isn't it best that biotechnologists are racing towards solutions to minimise those impacts?
You can find a SACE biology tutor near me on Superprof to help you understand or master these concepts.
References
- Nagwa. “Lesson Explainer: Specialized Cells | Nagwa.” Www.nagwa.com, 2024, www.nagwa.com/en/explainers/824137934571/. Accessed 25 Jan. 2026.
- Nature education. “Cell Metabolism | Learn Science at Scitable.” Www.nature.com, 2014, www.nature.com/scitable/topicpage/cell-metabolism-14026182/. Accessed 25 Jan. 2026.
- LibreTexts. “Unit 4: Cell Metabolism.” Biology LibreTexts, 16 May 2016, bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Biology_(Kimball)/04:_Cell_Metabolism. Accessed 25 Jan. 2026.
- LibreTexts. “2.9: Cell Reproduction- Mitosis and Meiosis.” Biology LibreTexts, 26 Jan. 2023, bio.libretexts.org/Courses/Cosumnes_River_College/Introductory_Anatomy_and_Physiology_(Aptekar)/02:_Cells_and_Tissues/2.09:_Cell_Reproduction-_Mitosis_and_Meiosis. Accessed 25 Jan. 2026.
- Ask the Scientists. “Cell Signaling: How Your Cells Talk to Each Other.” Ask the Scientists, askthescientists.com/qa/what-is-cell-signaling/. Accessed 25 Jan. 2026.
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