High school biology
Intro to eukaryotic cells
Overview of eukaryotic cells and how they differ from prokaryotic cells (nucleus, organelles, and linear chromosomes).
What would it be like to live in a one-room cabin? Well, things would probably be pretty simple. You would eat, sleep, work, and relax in a single room—which might be a bit cramped, but would certainly make cleaning the house a snap!
Prokaryotic cells, the simple cells of organisms like bacteria, are sometimes compared to one-room cabins: they don't have internal membranes, so they’re like a single room with no walls to carve it up. If we extend this analogy to eukaryotic cells, the more complex cells that make up plants, fungi, and animals, we'll find that they're a definite step upward in the real estate market.
Just as a large family home is split into many rooms with different purposes (bedrooms, bathrooms, kitchen, living room, etc.), so eukaryotic cells contain a variety of different compartments with specialized functions, neatly separated from one another by layers of membrane. This organization lets each compartment maintain its own conditions, the ones it needs to carry out its job.
For instance, compartments called lysosomes, which act as recycling centers for the cell, must maintain an acidic pH in order to dispose of cellular waste. Similarly, structures called peroxisomes carry out chemical reactions called oxidation reactions and produce hydrogen peroxide, both of which would damage the cell if they weren’t safely stored away in their own “room.”
The ability to maintain different environments inside a single cell allows eukaryotic cells to carry out complex metabolic reactions that prokaryotes cannot. In fact, it’s a big part of the reason why eukaryotic cells can grow to be many times larger than prokaryotic ones.
Prokaryotic vs. eukaryotic cells
What are the key features of eukaryotic cells? Unlike prokaryotic cells, eukaryotic cells have:
- A membrane-bound nucleus, a central cavity surrounded by membrane that houses the cell’s genetic material.
- A number of membrane-bound organelles, compartments with specialized functions that float in the cytosol. (Organelle means “little organ,” and this name reflects that the organelles, like the organs of our body, have unique functions as part of a larger system.)
- Multiple linear chromosomes, as opposed to the single circular chromosome of a prokaryote.
Eukaryotic cells are much more complicated than those of prokaryotes. They are packed with a fascinating array of subcellular structures that play important roles in energy balance, metabolism, and gene expression.
In the articles and videos that follow, we’ll take a tour through eukaryotic plant and animal cells, exploring the unique structures they contain and the role that each structure plays in the life of the cell.
Already know what part of the cell you want to visit? Use the list below to jump to your region of interest:
Diagram of a typical animal cell:
Diagram of an animal cell with components lettered.
Diagram of a typical plant cell:
Diagram of a plant cell with components labeled.
Want to join the conversation?
- Why are plant cells typically square (if they are) and why do they have a much larger vauole than animal cells?(15 votes)
- They are squarish because they have a stiff cell wall that forces them into that shape. If you meant vacuole, I think they have a larger vacuole because they have more need to store food than animals. In case of drought or famine, animals can move on to somewhere else if they need to get food or water, plants can't.(75 votes)
- Procaryotic cells lack vacuoles too then?(6 votes)
- Yes. Only eukaryotes have vacuoles.(30 votes)
- how come animal cells don't have a cell wall(9 votes)
- An animal cell needs to allow mobility for that animal so only has a cell membrane, a plant cell however has a cell wall to give the cell ridged structure and a plant doesn't move by itself so doesn't need mobility but rather it have protection.(20 votes)
- In the above diagram the author gives us an example of what a plant cell looks like and I noticed that the cell has an abnormally thick cell wall. What is the reason for thick cell walls in plants?(10 votes)
- Cell walls not only provide structure, and protect from mechanical damage, they also prevent the cell from bursting as plant cells need to continually absorb water to survive.(11 votes)
- Does the nucleus have a phospholipid bilayer?(6 votes)
- Actually it is surrounded by a double membrane which has 2 phospholipid bilayers each.(13 votes)
- The Endoplasmic Reticulum in a eukaryotic cell is the transport network of the cell and it extends from and connects the nuclear membrane to the plasma membrane of a cell. But then whenever we draw a diagram of a typical plant or animal cell, we never extend it to the plasma membrane- we always leave it somewhere in the cytoplasm. So, it should be extended, shoudn't it? And in that sense all our diagrams are theoretically wrong?(8 votes)
- Well, from endoplasmic reticulum vesicles are formed and transport things to Golgi apparatus, where it may be modified somehow, sent back to ER or further to cell surface. So the whole network is: ER -> vesicle -> Golgi -> vesicle -> cell plasma membrane(5 votes)
- are there any unicellular eukaryotes? if there are, names ?(3 votes)
- Yes, there are many unicellular eukaryotes. In fact, they have their own kingdom in the standard five kingdom classification scheme in biology called Kingdom Protista. Kingdom Protista is divided into subkingdoms of Protozoa and Algae. In Subkingdom protozoa, you have organisms like amoeba, euglena, volvox, paramecia, even plasmodia (the microorganisms that causes malaria), just to name a few. Most types of algae are also unicellular eukaryotes.(10 votes)
- Why is there a nucleolus? Shouldn't the production of DNA just be spread evenly around the nucleus?(6 votes)
- The nucleolus is a region from the nucleus where the different RNAs are found. It is also the site where ribosomes are joined. It´s important to mention that ribosomes are made 1/3 from proteins and 2/3 from RNA. Proteins for the ribosome are exported from the cytoplasm to the nulcleus trough the nuclear pores.(4 votes)
- Why the eukaryotic cells can carry out complex metabolic reactions but prokaryotic cells cannot can be the reason to the truth that eukaryotic cells are larger than prokaryotic cells?(5 votes)
- also there are more specialized organelles (assigned to carry out specific processes) than a prokaryotic cell.(3 votes)
- in the above notes and diagram, does cytosol also mean cytoplasm(4 votes)
- Cytosol is a part of the cytoplasm, specifically a liquid solution made of water and other molecules. Cytoplasm consists of cytosol and organelles such as mitochondria and the like.(4 votes)