When you think of the term specialized cell, what do you think of? Well, when I was younger, I used to imagine this super cell that was really important and did all of these special tasks. I don't know, like some kind of special agent cell. Yeah, I kind of had that wrong.
A specialized cell is a cell that has a structure that suits its function. Many cells have really different functions, and so their structure can vary greatly. When you see a lot of pictures of plant cells and animal cells, you might start to think that this is how they all look. All the animal cells and all the plant cells, they might start to kind of look the same in diagrams. Well, plant cells and animal cells definitely have structures that are unique to them.
We have that covered in our intro to cells video. But because cells have different functions, depending on their cell type, and the activated genes that they have, cells are going to have different structures too. They're going to be specialized. Now, the process for cell differentiation, which really explains how cells become specialized, is a topic for another one of our videos. This video is going to focus on examples of specialized cells so that you can discover how different they really are and why that's so important.
We can't go through every plant and animal cell, obviously. we can give you some great examples. Let's start with plant cells. Plant cells can have all kinds of specialization, depending on their function.
I mean, you can just look at a cross section of a leaf and see all kinds of specialization. At the top here, also often at the bottom of the cross section too, you can have a waxy cuticle layer, a protective layer that covers plant epidermal cells. Plant epidermal cells, among their many functions, are important in forming a boundary from the outside. They help keep plants from losing precious water.
Epidermal cells can be up here on the top of the leaf, that's the upper epidermis, and they can also be down here on the bottom, the lower epidermis. Depending on the type of plant and where it might be living, the layer could be just one cell thick or several cells thick, especially if the plant lives somewhere where it's going to have to protect against environment extremes. Many plant epidermal cells do not even contain chloroplasts because For a lot of plants, that's not a main function for epidermal cells.
Guard cells are specialized epidermal cells that have an important job of controlling the opening and closing of stomata, which are pores in the leaf. They tend to be at the bottom of the leaf, but as always, there are some exceptions. See, you want stomata to be open to let the exchange of gases through. But you don't want them to be open if you don't have enough water in the plant, because water can get out. There's a balance.
We have a video on that. Here are more specialized epidermal cells. Trichomes. Now, for plants, these can be plant hair cells.
And maybe not like what you were thinking. These epidermal cells can be hair-shaped, and they have all kinds of different functions. Some of them are protective and can secrete toxic substances to protect against insects that might want to eat them. Some act like light reflectors to help protect plants that live in really hot areas that get a lot of direct sunlight.
Now a side note on trichomes. My favorite plant of all time is the sundew. It's a carnivorous plant that I actually used to grow like crazy when I was a kid until I got a little too crazy.
But I digress. Anyway, this plant actually has trichome cells that produce enzymes that digest insects because it's a carnivorous plant. Yep. Still in this leaf cross section, look at this layer. This is the mesophyll.
Here are the palisade mesophyll cells. These cells are really important for capturing light, so they're specialized for this task. Guess what they have a lot of?
Chloroplast. Lots of chloroplast, making glucose from the sun, food for the plant. Underneath it, take a look at these spongy mesophyll cells. These cells that make up this area are pretty loosely packed.
They have irregular shapes. They can have chloroplasts, but they're not as strong as the ones in the plant. But in many plants, they may not have as many chloroplasts as the palisade mesophyll cells because in many plants, the spongy mesophyll cells don't do as much photosynthesis as the palisade mesophyll cells do. Their irregular shape combined with loose organization gives space for gas exchange, which you need for photosynthesis.
This vein here contains the xylem and the phloem. We talk about these vessels in another clip. The cells that make up these vessels are specialized for transporting water in the xylem or products from photosynthesis in the phloem.
Ok, so we just saw a few examples of specialized plant cells. Let's take a look at specialized animal cells. How about the animal cells in your human body? Let's take red blood cells, RBCs, erythrocytes, so many names.
They contain hemoglobin in their cytoplasm which is a protein that helps them carry oxygen. They have a disc shape which maximizes surface area for carrying oxygen. And they are also fairly flexible, which is helpful when squeezing through small capillaries.
Here's a fun fact. When they are mature, they actually don't have a nucleus. Or a lot of other organelles. Again, it's all about maximizing that space for carrying oxygen. By just the name, you might hear white blood cells and think that they are very similar to red blood cells, just a different color.
But in reality, they are extremely different in structure and function. There are many different kinds of white blood cells. Some of them are classified as granulocytes, which means a special part of their structure is that they have these granules in their cytoplasm, which when released can aid in destroying pathogens. Many white blood cell types can have an irregular shape.
with a structure that allows them to engulf foreign particles. How about muscle cells? Many muscle cells can have more mitochondria than many other body cell types because of their need for ATP energy. Now depending on how their overlapping filaments are arranged, they can be considered striated, which basically means a striped appearance, or not striated.
Their shape differs too. Smooth muscle has a shape that kind of tapers at each end. often described as a spindle shape.
Skeletal muscle cells are long and cylinder shaped and often bundled. They can have a lot of nuclei too, which is definitely interesting. If you're curious about why, it has to do with the fact that these cells develop from myoblasts, which have fused together.
So, to the Google to find out more. Now cardiac muscle cells have many similarities to skeletal muscle, but because they have such an important function with the beating of the heart, they have to be in sync. They have what are called intercalated discs and those join them and help carry the signal to maintain the heartbeat.
Cardiac muscle cells are often branched and they too can have more than one nucleus. With our limited time, we want to mention one more specialized animal cell, neurons. Oh boy, where do we begin?
Neurons are the cells that can sense a stimulus and transmit signals. Common places to find them include your brain or your spinal cord. These things can be over a meter long in humans. One meter. Microscopic still, but wow, just look at this beautiful cell.
Its structure is specialized for signal conduction. In the neuron, structures called dendrites receive impulses, and axons transmit the impulse either to another neuron or to a cell that it's targeting. Like one of the muscle cells we just mentioned.
By the way, this transmitting of the signal, which can occur in an event called the action potential, it's going to have to be in another video. The action potential is just a beautiful, amazing process, and these cells are specialized for it. Phew, okay, that's a lot of specialized plant and animal cells. And that's just a few selected examples.
One thing to keep in mind is that these specialized cells They can make up specialized tissues in both plants and animals and they function together. More about tissues in our biological levels of organization video. Well, that's it for the Amoeba Sisters and we remind you to stay curious.