Lesson video

- Hello and welcome to today's Oak Academy Science Lesson.

My name is Mrs. Bowes.

I'm looking forward to teaching you today.

To make sure you are ready for the lesson, please have in front of you a pen and some paper and then we can get going.

The title of today's lesson is Specialised Cells and the outcome is to identify different specialised cells and explain their function.

And this is a science lesson and it's part of the topic in key stage four called, Cell Biology.

If you need to pause the video now to write the title down, please do and then press play when you're ready to begin.

Today's lesson is going to have some words in it, which you might be unfamiliar with or you may have heard before.

And these are the key words that will help you to understand some of the more difficult concepts.

So today's key words are biconcave.

A biconcave shape is a flat disc with dips on both sides.

Fertilisation occurs when the sperm cell meets the egg cell and then a zygote is formed.

Photosynthesis is a process where plants convert sunlight energy into glucose.

And finally, active transport is an energy requiring process where particles are moved from low to high concentration.

The outline of today's lesson on specialised cells is as follows.

The first thing that we're going to learn about is identifying different specialised cells from diagrams. And once we've done that, we're going to look more closely at the different features that those cells have, and we're gonna explain how specialised animal cells relate to their function.

And then finally, we're going to do the same thing, but for plant cells, and explain how specialised plant cells relate to their function.

Let's begin with we're just going to identify some specialised cells.

So looking at these pictures here, do you know what any of those cells might be called? Just have a quick think now, some of them you might recognise, others not, but could you give me the names of any of them right now? Let's have a look.

So the first cell on the left is a nerve cell, which forms part of our nervous system.

Then next to the nerve cell, you've got the ciliated cells, might or might not have heard of those.

So they've got these funny little hairs that come up the top of them.

You probably know this one, this is a sperm cell, that's the male sex cell.

This picture here is showing you a red blood cell, so they are found in our blood.

And then the next one is a root hair cell.

So we find those in the roots of plants.

And then lastly, some of you might have just written plant cell for this or thought plant cell, it is a plant cell, but it's actually a specialised cell within a plant, it's called a palisade cell.

And these are the different specialised cells that we are going to be looking at today.

Nerve cell, ciliated cells, sperm cell, red blood cell, root hair cell, and the palisade cell.

These are examples of specialised cells.

Specialised cells have specific features that allow them to carry out their function and the function just means their job.

If we go back to these specialised cells we've just spoken about, could you tell me which of these cells do you find in plants and which are found in animals? So just have a quick think, animal or plant, let's see if you've got it.

So nerve cell, animal, ciliated cells, also animal, sperm cell, animal, red blood cell, animal, and then root hair cell and palisade cell, they are both found in plants.

Hopefully you got that.

So if we look at these specialised cells, we find the pictures of these cells in the human body.

So we've got the sperm cell, the red blood cell, the ciliated cells, and the nerve cells.

Why do you think that we need these specialised cells in our human bodies? Hopefully what you are thinking is that each of those cells has got a specific function within the body and therefore, they've got features that make them really good at carrying out that particular job.

So not all cells are designed to do the same job and because of that, it means they're gonna have different structures and features that help them to carry out whatever their job is.

So if we take a sperm cell and a red blood cell, they're both specialised cells in the human body, but they've both got very different functions.

So each feature of a specialised cell helps it to carry out that function.

And those features could include the shape of a cell or it could also be the subcellular structures that are contained within it.

So if you look at the sperm and the red blood cell, they have very, very different shapes and they also do have different subcellular structures within them.

And that is so that they can carry out their specific job really, really well.

And part of today's lesson is going to be explaining the features of each specialised cell and saying why it helps that cell to carry out its function.

Let's start some questions and see how much we have learned so far.

So first question is what is this specialised cell? So there's a picture there, what is that a picture of? Is it A, a palisade cell, B, a nerve cell, or C, a root hair cell? Nice and easy to this one, root hair cell, C.

Next question, what is this specialised cell? A, sperm cell, B, an egg cell, or C, a red blood cell? Have a think.

Again, this one's quite easy, it's a sperm cell.

What are these specialised cells? A, nerve cell, B, ciliated cell or C, a palisade cell? Hopefully we know this one, it's B, they are ciliated cells.

And then finally, can you name each of the following specialised cells that are in these pictures? So you haven't got the prompts this time so they're a little bit more tricky.

What are the names of those three specialised cells? Start with the left hand side first and move your work cross.

Hopefully you've got this, but the first one is a nerve cell, the middle is a red blood cell, they're both animal cells.

And then the final cell is our palisade cell, which is found in a plant.

Absolutely amazing if you remembered that.

Really, really good work.

I think now it is time for us to start our first task.

The first thing I would like you to do is to complete the table on your sheet.

You have a diagram of six specialised cells, and then underneath I would like you to write the name of that specialised cell and then tell me whether you would find that in a plant or in an animal.

So pause the video now and when you're ready for me to go through the answers, press play and we will.

Okay, let's go through the answers.

So the first cell's a root hair cell, and we find that in a plant.

The second cell is a nerve cell, that is an animal cell.

Then we've got the sperm cell, which again is an animal cell.

The next one is a red blood cell, which again is in an animal.

And then we've had our ciliated cells, also found in animals.

And then finally, we have the palisade cell and that is found in a plant.

Mark your work.

Really big well done if you remembered all the names and could tell me where they were found, that is an excellent start to today's lesson.

If you need a little bit more time to correct your work, just pause the video and then pick back up again, then we are going to carry on.

So now we have identified our different specialised cells and we're going to move on to explain how specialised animal cells relate to their function.

So we're just focusing on focusing on animal cells now.

So again, quick recap, what is this specialised cell? We should know, we've just done it.

What is that picture showing us? It is showing us a nerve cell.

And nerve cells, their function is to transmit electrical impulses throughout the body and they form part of our nervous system.

So here you can see two nerve cells that are near to each other.

And in reality our body has got lots of nerve cells within it, but they are connected, and their job is to pass electrical impulses from one nerve cell to the other to the other.

And then that information gets sent to our brain and our spinal cord and it helps us make all the decisions that we do in a day and also helps us to move around.

It controls almost everything that we do.

So nerve cells are very important, but how do they work? Well, first of all, the electrical impulse arrives in the first nerve cell.

So that's what labelled on this diagram.

And then you see these little purple lines, they are representing the electrical impulse.

So that electrical impulse travels down the nerve cell.

And you can see that each end of the nerve cell has got these branched parts coming out of it, they're branched, and that helps connect one nerve cell to the next nerve cell.

So the branch stems then connect to different nerve cells so that electrical impulse is able to be passed between two nerve cells, and then the electrical impulse travels to the connecting nerve and passes down it.

So how is the nerve cell adapted to be really good at carrying these electrical impulses around the body? Well the first thing is that it is very, very long and thin.

And because they're long and thin they can carry impulses over long distances very quickly.

You think we are moving and making decisions really quickly all the time and that is only able to happen because our nerve cells are long and thin and they carry those electrical impulses very fast throughout our body.

Another thing that they have is something called a myelin sheath, which are these little rectangles that go down the longer length of the nerve body.

The myelin sheath surrounds the nerve so that impulses can travel faster along the body.

And then finally, we touched on this before, but there are branched connections at each end of the nerve cells so that they can connect to other nerve cells and then that means they can transmit those impulses really quickly.

So there's three parts or three features of the nerve cells that make them really good at transmitting electrical impulses.

They're long and thin, they have a myelin sheath, and also they have branched connections.

Moving on to a different type of specialised cell, remember we're with animal cells right now, what is this specialised animal cell here? Hopefully you've remembered it.

It is a red blood cell.

The job of the red blood cells is to carry oxygen around the body for respiration.

So the oxygen we breathe in when we inhale and the oxygen travels down trachea into our lungs and the oxygen diffuses into the red blood cells in the lungs.

So now we've got red blood cells that are full with oxygen and inside the red blood cells is a substance called haemoglobin and the oxygen binds to that haemoglobin in the red blood cells and is delivered to all parts of the body for respiration.

The reason why the red blood cells are so important is because every single cell in the body needs to respire, it releases energy and that is what keeps all the cellular processes going.

Effectively, that is what keeps us alive.

So what are the features of the red blood cell that make it excellent at carrying oxygen around the body? Well the first one is that the red blood cell has no nucleus.

The reason it has no nucleus is to make sure that there is a maximum amount of space inside the nucleus to carry as much oxygen as possible.

Now I do want to say at this point, that just because the red blood cell doesn't have a nucleus, it doesn't make it a prokaryotic cell, it is still a eukaryotic cell.

It's just a specialised eukaryotic cell that doesn't have a nucleus.

Also, coming back to one of our keywords of the lesson, the red blood cell has that biconcave shape, so it's a flat disc with dips on either side.

And the reason it has that shape is so that there's a really large surface area for all of that oxygen to get into the red blood cell in the lungs.

The more surface area there is, the more oxygen can diffuse into the cell.

So both of these features are about trying to get as much oxygen into that red blood cell as possible.

So the two features of red blood cells, no nucleus, so that there's more space inside the cell, and also the biconcave shape to increase the surface area so they can absorb more oxygen.

Third specialised cell, what is this a picture of? Can we remember? This is our sperm cell.

Now sperm cells are the male sex cell, and their job is to swim to meet the egg cell before fertilisation occurs.

So remember, the sperm cell has to travel through the cervix, has to go through the uterus to find that egg cell.

And we've got a picture here of the sperm and the egg, and the sperm cell swims towards the egg, they fuse together, fertilisation occurs, which is the beginning process of making a baby.

There are actually millions of sperm that are released, but only one of those sperm cells can fertilise the egg.

So the job of the sperm cell is to try and swim as fast as it can to get to that egg for fertilisation to occur.

So what features does the sperm cell have that make it excellent at swimming towards the egg and fertilising that egg? It's not just about swimming, it's also about making sure it can fertilise the egg.

The first thing it does is it has a tail.

The tail makes it a streamlined shape.

It means that it can swim towards the egg very effectively.

Second thing is, just before you get to the head of the sperm, there is a lot of mitochondria.

Remember, mitochondria are where aerobic respiration occurs that releases lots of energy.

That energy is needed by the sperm for movement.

So the sperm's got many mitochondria so that there's energy released for movement.

And then finally, in the head of the sperm, there's something called an acrosome.

That acrosome contains lots of enzymes, so that the egg cell membrane can be broken down.

So when the head of the sperm meets the egg, the enzymes in the acrosome will be released, and they help to break down the membrane of the egg so that fertilisation can occur.

So the three features of a sperm cell are a tail, to make it streamlined for swimming, many mitochondria, to release energy for movement, and the acrosome, which contains enzymes to break down the cell, the membrane of the cell.

And our final animal cell.

Remember what these are? Probably the one you are least familiar with coming into this lesson.

This is the ciliated cells.

Now the job of the ciliated cells is to move mucus up and out of the lungs.

So we're going up and out of the lungs.

And ciliated cells, on the top of them, have got these tiny little hairs that are called cilia, that's why they are called ciliated cells, and those cilia line all of the airways.

So this picture here is showing you the lungs, the trachea, the bronchi, and they're the parts of the airways, and the ciliated cells line the bronchus and the trachea and their job is to move mucus up and out of the lungs.

Now the small hairs on the top of those ciliated cells are called cilia and they move together to sweep the mucous up and outta the lungs.

And what I mean by they move together is that all of the hairs, the cilia, will be up in one direction at one time, and then they will move together to kind of go a bit more flat, and then then move together again to go more upright.

So they're kind of wafting the mucus along the airways so that it can come up and outta the lungs.

So the cilia work together to move the mucus up and out.

We should be ready now to test our understanding of what I've just been explaining.

So have a go at this question.

This is about the functions of the specialised animal cells.

So there are four specialised animal cells, they're A, B, C, D, and there are four statements.

I would like you to match the picture to the function.

So you just need to write the letters in order of what they would come up in each statement.

So have a think about it and then we'll go through and see if you've got the right answer.

Okay, let's check.

So swim to the egg before fertilisation can occur.

That's B, that's a sperm cell.

Carry oxygen around the body for respiration.

C, that's a red blood cell.

Line the airways to move mucus up and outta the lungs, is D, our ciliated cells.

And finally, transmit electrical impulses around the body is A, that is our nerve cells.

Really, really well done if you managed to get all of those correct.

Let's do some more questions.

So what do you call the sheath that surrounds nerve cells? A, an impulse sheath, B, an myelin sheath, or C, a haemoglobin sheath? Hopefully here you've got B, a myelin sheath.

Next question.

Which feature does not allow nerve cells to pass impulses quickly? A, branched connections, B, myelin sheath, or C, contains haemoglobin? Are we on a roll, let's see what we've got.

That is C.

It doesn't contain haemoglobin, that was in the red blood cells.

Next question.

What is the function of the cilia? A, to work on their own, moving mucus up and out of the lungs, B, to work together to move mucus down into the lungs, or C to, work together to move mucus up and out of the lungs? What do you think with this one? This one's a little bit more tricky, 'cause the statements are quite similar but it is C.

The cilia work together and they move mucus up and out of the lungs.

Really good job if you managed to get that one correct.

A true or false question now.

Sperm cells do not contain mitochondria, is that true or false? So pick that first, and then justify your answer.

A, photosynthesis takes place in the mitochondria and sperm cells don't photosynthesize, or B, respiration takes place in the mitochondria which releases energy for movement.

You have a go at this.

Let's go through it.

So sperm cells do not contain mitochondria, that is false.

Sperm cells do contain mitochondria.

And the justification here, well respiration takes place inside the mitochondria and that releases energy for movement.

The problem with statement A is that photosynthesis doesn't take place in the mitochondria.

Photosynthesis takes place in plant cells in the chloroplasts.

So A is incorrect.

So final question, why do sperm cells have an acrosome? A, it makes a sperm streamlined so it can swim faster, B, it is full of mitochondria that releases energy for movement, or C, it contains enzymes that help break down the cell membrane.

This one is C.

All of those statements are actually true for the features of a sperm cell, but only C relates to the acrosome.

The acrosome contains enzymes, that breakdown the cell membrane.

Absolutely amazing job if you managed to remember all of those.

There's a lot of information there.

So you're doing really, really well.

Now it's time for us to apply that knowledge into our second task.

So the first thing you need to do is fill in the missing words using the key words below.

So pause the video now and have a go at that task and press play when you are ready to go through the answers.

Okay, let's go through the answers.

So nerve cells are long and thin so that impulses can travel over long distances.

They have a myelin sheath that allows impulses to travel faster and they have branched endings so that they can connect to other nerve cells.

Amazing job if you've got all of those right.

Well done.

Let's move on to the second part of our task.

So this time you need to finish the sentences to explain how red blood cells are specialised.

This is a little bit more tricky because you have to do a bit more of the sentence writing yourself, but the sentences have been started for you.

Where there is a blank bit at the beginning, so red blood cells have no, and there's a blank, you need to fill in that word as if it was a fill in the gap, but then you need to go on to explain why they have that feature.

So pause the video again and then press play when you're ready for me to go through the answers.

Okay, let's see how we've done with this one.

So red blood cells have got no nucleus so that they can carry more oxygen inside of them.

Red blood cells have a biconcave shape so that they can absorb more oxygen in the lungs.

Amazing, amazing work if you managed to get those correct.

If you need to pause the video now just to spend a little bit longer adding anything into your work, please do and then pick up so we can carry on with the rest of the tasks.

And then the final part of this task is to answer the following questions in full sentences.

So the first question is, what are the small hairs on ciliated cells called? Question ii, is what is the function of the cilia? And then iii is explain the three structures in a sperm cell that allow it to travel to the egg and fertilise it? So this is a little bit more challenging.

Do spend enough time, making sure you write in full sentences, pause the video to complete it and then press play when you are ready for me to start going through the answers again.

Hopefully you had a really, really good go at that.

So for question i you should have had the small hairs on ciliated cells are are called cilia.

For question ii, the function of the cilia is that the cilia moved together to move mucus up and out of the lungs.

And then iii, the three different structures in a sperm cell.

It doesn't matter what order you have written these in as long as you have got all of them.

So even if you start with a different one to what I'm starting with, that's okay, just mark them as and when I bring them up.

The first one I've got is that it's got a tail which allows the sperm to be streamlined and swim towards the egg.

The second feature is that there's many mitochondria that release energy for movement.

And then the final feature is the acrosome in the head, which contains enzymes that breakdown that cell membrane.

Again, if you need to pause the video to add anything into your work, please do and then press play when you're ready to continue with the rest of the lesson.

Right, we're moving on now, so the final part of our lesson, which is to explain how specialised plant cells relate to their function.

So this bit is very similar to the last bit.

We're looking at the features of plant cells that are specialised and relating that to their function.

So back to the beginning of the lesson, can you remember the name of this specialised cell? This is a palisade cell.

Palisade cells absorb lots of light energy from the sun as this is where photosynthesis takes place.

So there's kind of two functions for the palisade cell.

One, they have to absorb lots of light and two, photosynthesis takes place within the chloroplasts of the palisade cell.

So there the chloroplasts have absorbed the sunlight for photosynthesis.

So that arrow there is pointing to the chloroplast.

And the chloroplasts contain a substance which absorbs the light and that is where photosynthesis takes place.

So this is how the palisade cell is adapted to be able to absorb light and also carry out photosynthesis.

First of all, there are loads of chloroplasts in palisade cells.

Not all cells in plants contain chloroplasts.

Root cells, for example, root hair cells do not contain chloroplasts, because no photosynthesis takes place there.

Palisade cells have lots of chloroplasts because lots of photosynthesis takes place in palisade cells.

Chloroplasts also contain a green pigment called chlorophyll.

Chlorophyll absorbs sunlight and photosynthesis takes place in the chloroplasts.

You also find palisade cells at the top of leaves and that is so that they can absorb as much energy from the sun as possible.

So this picture here is showing you the top of the leaf and the bottom of the leaf, and as you can see there's lots of palisade cells on the top of the leaf.

And that means that when the sun is shining, all of that sunlight energy is absorbed by the palisade cells.

If the palisade cells were at the bottom of the leaf, they wouldn't have very much direct sunlight so they wouldn't be able to absorb all of the sunlight energy.

And this picture here is showing you a cross section of a leaf, and that is if you chopped a leaf in half down the middle.

And again, you can see in the top layer, you've got the vertical palisade cells that are really tightly packed at the top.

And this is so they can absorb as much light as possible for photosynthesis.

Now another feature of palisade cells is that they have this column shape, and that is really important because it allows 'em to be packed really closely together at the top of the leaf.

That means you can get as many palisade cells as you possibly can, put in at the top of the leaf.

If they're tightly packed at the top, that means there's more palisade cells there, so more sunlight can be absorbed.

The more sunlight that's absorbed, the more photosynthesis that's going to take place.

Obviously quite a lot of information on the last few slides.

So just to summarise all that up, the features of a palisade cell that allow it to carry out photosynthesis and absorb as much light as possible are that they contain many chloroplasts where photosynthesis occurs.

They're also located at the tops of leaves to absorb more sunlight and they have this column shape to fit as many chloroplasts together at the tops of leaves to absorb as much sunlight as possible.

Moving now onto our root hair cell, the function of a root hair cell is to absorb water and minerals from the soil.

So this picture here is just showing you the root hair cell and its whole job is to try and absorb as much water and as many minerals as it possibly can from the soil and bring them into the plant.

So how is the root hair cell adapted and what features does it have to make it really good at absorbing as much water and minerals as possible? Well, the first thing it has is many mitochondria.

And again, the mitochondria is where aerobic respiration occurs.

Lots of energy is released through aerobic respiration.

Now this is important in the root hair cell because the minerals in the soil, they need to be actively transported into the root.

That is an energy requiring process.

So there are lots of mitochondria in the root hair cell to release that energy that's needed to actively transport minerals from the soil into the root hair cell.

Root hair cells also have a very long thin projection coming out of them.

This increases the surface area for the absorption of water and minerals.

So the larger the surface area, the more water molecules and minerals are gonna be able to actually get into the root hair cells.

That projection just increases the surface area.

And then finally they've got a very, very large vacuole, and this is to store as much water as possible in that root hair cell.

So the three features of the root hair cell, lots of mitochondria which release energy for active transport of minerals.

Number two, a long thin projection to increase the surface area so as many water and mineral molecules can get into the root.

And finally, a really large vacuole to store as much water as possible.

Let's check our understanding.

Again, give it your best go, I'm sure you're gonna do amazingly.

So in which subcellular structure does photosynthesis take place? A, cytoplasm, B, chloroplasts or C, mitochondria? You have a go.

This is A, chloroplasts.

Photosynthesis takes place in the chloroplasts.

Next question, which is not true for palisade cells? A, they are located at the top of leaves to absorb more sunlight.

B, they do not contain many chloroplasts.

Or C, they have a column shaped to be pack closely together.

Remember you are saying, which is not true for palisade cells.

This one, we should get this one, this is B.

Palisade cells contain loads of chloroplasts.

So B is incorrect.

They have lots of chloroplasts, remember that is where photosynthesis takes place.

Next question, why do root hair cells have long projections? A, to decrease the surface area for water absorption, to stop minerals from entering the cell, or to increase the surface area for water absorption? This one is C, to increase the surface area for water absorption.

True or false, root hair cells have many mitochondria, justify it.

Is it because energy's needed to absorb minerals from the soil by active transport, or, B absorption of minerals is passive and no energy is needed? This is true.

And the reason it's true is because energy's needed to absorb minerals from the soil by active transport.

Really quickly now, so root hair cells have a large something to store water.

A, Cell membrane, B, nucleus, or C, vacuole.

This one is C.

They have large vacuole to store water.

Time for you now to start the final task.

So answer the following questions in full sentences.

If there's keywords given, please use those as well in your answers.

Pause the video now and then press play when you're ready for me to go through the answers.

Okay, so for A, i, you should have had palisade cells are located at the tops of leaves.

For ii, palisade cells have a column shape.

This means they can be closely packed together at the tops of leaves to absorb more sunlight.

Next questions.

Again, have a go at these on your task sheet and then press play when you're ready for me to go through the answers.

So what you should have had is chloroplasts contain a green pigment called chlorophyll that absorbs sunlight.

The more chloroplasts, the more sunlight is absorbed, and therefore the more photosynthesis can take place.

If you need to pause the video to spend a little bit longer trying to make your answers a little bit better, then please do.

If not, just keep going.

The final task today is to label this diagram of a root hair cell and tell me how it is adapted to its function using these keywords.

So again, pause the video and press play when you're ready for me to show the answers.

So what we should have had is they're long and thin with a projection to increase the surface area for absorption of water and minerals.

You should also have had, they've got a large vacuole to store as much water as possible.

And finally, they've got many mitochondria because mitochondria release energy that's needed for active transport of minerals from the soil.

Now you might have worded things slightly differently, but just read through and check you've got all of the information that you need, add anything in if you need to.

That is the end of today's lesson on specialised cells, I think you have done an amazing job.

There was quite a lot of knowledge in here, but you've done an amazing job of trying to remember it all, so really, really, really well done.

I'm just gonna do a quick summary of everything that we've learned in this lesson.

So the first thing we learned was that specialised cells contain specific features that allow them to carry out their functions.

We said red blood cells have no nucleus.

They have a biconcave shape to allow them to carry and absorb as much oxygen as possible.

Nerve cells are long and thin, they've got branched ends and a myelin sheath to transmit impulses quickly.

Sperm cells have that tail, they've got an acrosome, and they've got lots of mitochondria.

Ciliated cells line all the airways and they're covered in cilia that move mucus up and outta the lungs.

And palisade cells are found at the tops of leaves.

They contain lots of chloroplasts and have a column shape.

And finally, root hair cells in plants have got long projections, they've got a large vacuole and they've got lots of mitochondria.

That is the end of today's lesson.

There's an exit quiz for you to complete just to consolidate some of that learning at the end of the lesson.

But I think you've done an amazing job, I've really enjoyed it and I look forward to seeing you again soon.

Bye.