Lesson video

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

My name is Mrs. Bowes.

I'm really looking forward to teaching you today.

To make sure that you're ready to learn.

Have with you a pen and some paper and then we can get going.

The title of today's lesson is Cellular Structures and the outcome is to describe cellular structures and to compare plant and animal cells.

This is a science lesson and it comes in the key stage four topic called Cell Biology.

Now there are some keywords in today's lesson that are going to help us to access some of the more difficult concepts and those keywords are photosynthesis.

So plants make their own glucose through photosynthesis.

Sub-cellular, sub-cellular structures are the smaller parts of cells that make them up.

So if you had a cell within it there are much smaller parts than the actual cell itself.

And those smaller parts are called the sub-cellular structures.

And semi-permeable, a semi-permeable membrane allows certain substances to pass through it, but not all substances.

And the structure of our lesson today on cellular structures is as follows.

The first thing we're going to do is identify some sub-cellular structures.

Then we are going to describe the function of those sub-cellular structures.

And then finally, we are going to compare plant and animal cells.

So let's get going with identifying some sub-cellular structures.

So both plants and animals are made up of cells.

Cells are the building blocks of all organisms. We are made up as humans of trillions of cells.

Which of these pictures is shown plant cells and which is showing animal cells? You had a guess? Well, the picture on the left is animal cells and they are neutrophils.

Neutrophils are a type of white blood cells involved in fighting infection and immune response.

And the picture on the right is plant cells and they are algae.

And you can see within the algae there are some chloroplasts.

For us to be able to see those images we would need to use something called a microscope.

So we use a microscope to magnify cells and look at them in more detail.

To magnify an image is to make an image appear bigger.

So we use a microscope to look at cells in more detail, which we otherwise wouldn't be able to with just using our eyes.

And cells are made up of different sub-cellular structures, which is why cells can look very different.

So these plants and animal cells look different because they've got different sub-cellular structures within them.

So these two pictures show what a typical plant and animal cell look like and they're different sub-cellular structures.

And you've got a typical animal cell on the left and a typical plant cell on the right.

There are some sub-cellular structures that are in both animal and plant cells and there are others that only plants have.

We are going to start by looking at the animal cells.

So this diagram shows us a typical animal cell and these are the sub-cellular structures that are contained within that typical animal cell.

From the very outside of the cell you've got the cell membrane, you've then got the nucleus, you've then got this jelly-like substance that surrounds all of the sub-cellular structures and that is called the cytoplasm.

And on a diagram, the cytoplasm just looks a little bit like empty space, but it is jelly-like and it surrounds all of the other sub-cellular structures.

Then you've got the mitochondria and then the smallest sub-cellular structures are called the ribosomes, which are often just very small circles dotted around this animal cell.

Now we're going to look at the sub-cellular structures in a plant cell.

So this image here is showing us a typical plant cell.

Some of the sub-cellular structures in a plant cell are also in an animal cell.

So we've got a cell membrane.

The cell membrane here though is not the optimal layer it's the second layer in from the outmost.

We still have ribosomes, the smallest sub-cellular structure.

We also have the cytoplasm, which is that jelly-like substance surrounding all of the other sub-cellular structures.

We've still got the nucleus however, we have also got something called a cell wall in a plant cell.

So the cell wall is the outmost layer in a plant cell.

We have mitochondria which we also had in animal cells.

However, plant cells also have something called a vacuole which stores lots of sap within it.

And we've got an extra sub-cellular structure in a plant cell called a chloroplast.

That's where photosynthesis takes place.

So the sub-cellular structures in a plant cell are the cell membrane, ribosomes, cytoplasm, nucleus, the cell wall on the very outside just in plants, the mitochondria, the vacuole, which is just in plants and the chloroplasts, which are just in plant cells.

Let's see how much of that we can remember.

So just give this your best go.

Don't worry if you get anything wrong.

So the first question, which sub-cellular feature is the label pointing towards? A the cell wall, B the cell membrane or C the nucleus? Now this is B, the cell membrane because this is an animal cell and the outmost layer of the animal cell is the cell membrane.

Which sub-cellular feature is the label pointing towards? A cytoplasm, B chloroplasts or C mitochondria? This is A the cytoplasm.

Remember that's a jelly-like substance that surrounds all the different sub-cellular structures.

Which sub-cellular feature is this label pointing towards? A mitochondria, B chloroplasts or C the nucleus.

This is C the nucleus.

Well done, if you're getting these so far.

And which sub-cellular feature is the label pointing towards here? A chloroplast, B mitochondria or C vacuole.

This is B the mitochondria.

Next question.

Which sub-cellular feature is the label pointing towards here? A vacuole, B ribosome, C nucleus? This is A the vacuole.

Which sub-cellular feature is the label pointing towards in this cell? A cell membrane, B ribosome and C cell wall? This is C, the cell wall.

Little bit more tricky now, what are the two missing labels on this cell? This is an animal cell.

So you should have had mitochondria and nucleus.

What are the two missing labels on this animal cell? You should have cell membrane and cytoplasm.

And what are the two missing labels on this plant cell? We have the cytoplasm.

And then finally we've got the chloroplast.

And remember that is unique to a plant cell.

Really well done if you manage to get those correct.

We are now ready to move on to the first task of the lesson.

Your job is to label the plant and the animal cell with the correct sub-cellular feature.

Pause the video now give it your best go and then press play ready for me to go through the answers.

Let's start with our animal cell.

So, you should have had cell membrane along the outside.

We've got the nucleus there.

Then the cytoplasm, the mitochondria and the ribosome.

Do check your spelling and correct anything.

If you need to pause the video, please do.

And then we'll go through the answers to the plant cell next.

So this is our plant cell.

We've got a few more labels on this one.

On the very outside is a cell wall.

Then we've got the chloroplasts that is a mitochondria and the nucleus.

Then we've got the cell membrane then we've got the vacuole, a ribosome and the cytoplasm.

Again, check your spellings, correct anything if you need to, if you need to pause the video, please do and then press play.

And we're going to move on to the next part of the lesson.

So we can now identify sub-cellular structures and we're going to move on to describe the function of those structures.

So first of all, a question.

Why do you think that cells are made up of different sub-cellular structures? Well, each sub-cellular structure has a specific function within the cell, and those functions are really important in cellular processes that keep us alive.

And we are going to learn about those different functions now.

So we're gonna start with the cell membrane.

Cell membrane is in both plant and animal cells and it controls what enters and exits the cell.

The cell membrane is partially permeable, which means it allows some substances to diffuse through, but not others.

The nucleus contains the genetic information the DNA and it controls the activities of the cell.

And again, both plant and animal cells have the nucleus.

Now the cytoplasm is a jelly-like substance that contains dissolved nutrients and salts and it's contained within both animal and plant cells.

And it surrounds all the sub-cellular structures and is where most of the chemical reactions take place inside cells.

The ribosomes, these are a very small sub-cellular structure and it's where protein synthesis occurs.

The word synthesis means to make.

So the ribosomes are where proteins are made.

And again, ribosomes are contained within both plant and animal cells.

The mitochondria is where aerobic respiration occurs and it releases lots of energy for cellular processes.

Now the plant cell has got three extra sub-cellular structures.

You've got the cell wall, the chloroplast and the vacuole.

Now the job with the chloroplasts is that it contains a green pigment called chlorophyll that absorbs sunlight and it's the site of photosynthesis.

Chlorophyll is what makes plants look green.

The vacuole contains sap, which helps keep the cell turgid.

We'll talk about what the word turgid means towards the end of the lesson.

And the cell war contains a substance called cellulose, which provides strength and support to the cell.

So plants don't have a skeleton like animals do and that means that the cells need to provide some level of support because when plants grow they have to grow upright and the cell wall helps to strengthen and provide support to the plant cells.

Right.

Let's ask some questions and see how much of that you can remember.

So first question what is the function of the cell membrane? A, where most of the cell reactions take place? B contains DNA and controls the cell's activities or C, controls what enters and exits the cell? This is C, it controls what enters and exits the cell.

Next question, what is the function of the nucleus? A, where protein synthesis occurs? B, contains DNA and controls the cells activities or C, it's the site of aerobic respiration? The nucleus contains DNA and controls the cell activity.

So that is B.

Well done if you've got those so far.

Next question.

Where are the proteins made in a cell? A, the cytoplasm, B the nucleus C, the ribosomes? Proteins are made in the ribosomes, C.

Remember, they're one of the smallest sub-cellular structures.

Where does aerobic respiration occur? A ribosomes, B mitochondria, C cytoplasm.

This is B.

The mitochondria.

Which part of a plant cell contains sap? A cell wall, B vacuole or C chloroplasts? It is the vacuole that contains sap, so that would be B.

Brilliant work.

What is the function of the chloroplasts? A photosynthesis occurs here.

B provides strength and support to the cell or C proteins are synthesised here.

This is A, photosynthesis occurs in the chloroplasts.

Next question, what is the function of the cell wall? A controls what enters and exits the cell.

B, where most of the chemical reactions take place or C provides strength and support to the cell.

The cell wall provides strength and support to the cell.

So that is C.

We are ready now to complete our second task of the lesson.

So the first part of this task is to complete the table below.

So you have been given the structure and the function of sub-cellular structures and you need to either complete the structure or write the function of that structure.

So pause the video now give it your best go and then press play when you're ready for me to go through the answers.

Okay, so the jelly-like substance where chemical reactions take place is the cytoplasm.

The function of the nucleus is that it contains DNA and controls the cell's activities.

Ribosomes is where protein synthesis occurs.

Mitochondria is where energy is released through aerobic respiration.

The function of the cell membrane is that it controls or enters and exits the cell and the cell wall contains cellulose which provides strength and support to the cell.

Remember that's just in plant cells.

The function of the vacuole is that it contains sap, which helps keep the cell turgid and then the chloroplasts contain chlorophyll and this is where photosynthesis occurs.

Absolutely amazing if you remembered all of that 'cause that's a lot of new information.

If you need to add anything to your answers then please feel free to pause the video and then press play to pick back up where we've left off.

Part B of task two is to answer the following questions in full sentences.

So you have a go at that now and then press play again and I'll go through the answers.

So the first question, would you find chloroplasts in an animal or a plant cell? Chloroplasts are found in plant cells.

They're one of the sub-cellular structures that are only found in plant cells.

What process happens inside the chloroplasts? Photosynthesis occurs inside the chloroplasts.

Well done if you've got both of those correct.

What is the green pigment found inside the chloroplast called and what is its function? The green pigment is chlorophyll.

So chlorophyll is a green pigment found in chloroplasts and its function is to absorb light energy.

And then the cell membrane is partially permeable.

What does this mean? The cell membrane is partially permeable because it allows some substance to diffuse through it, but not others.

Absolutely amazing if you remembered all of that detail.

Again, if you need to pause the video to add anything in, please do and press play so that we can carry on with the rest of the lesson.

Right.

So we now have identified sub-cellular structures.

We know the function of those sub-cellular structures and now we are going to spend some time comparing plant and animal cells.

So as discussed previously there are three sub-cellular structures plant cells have that animal cells do not have.

And those are the three, a cell wall, chloroplasts and a vacuole.

Those three structures are only found in plant cells not in animal cells.

Can you remember which sub-cellular structure photosynthesis takes place in? You've got this one.

It's the chloroplasts.

Now the reason that plants contain different sub-cellular structures is because they are photosynthetic organisms. That means that they carry out photosynthesis.

Plants use the sun's energy to react carbon dioxide which is from the atmosphere and water which plants get from the soil to make something called glucose.

Glucose is a sugar.

So carbon dioxide and water react together to make glucose, which is a sugar and oxygen.

And that process is called photosynthesis.

Animals get their glucose from food and drink, which is why their cells don't have chloroplasts.

Animal cells do not photosynthesize.

Now this is the main difference between plant and animal cells.

Something we have to know is that both animal and plant cells are respiring all the time.

It's what keeps organisms alive.

Cell respiration.

Glucose is needed for cell respiration.

Animals get their glucose from food and drink, which we can see on this slide.

Plants do not eat food and therefore they have to make their own glucose so that their cells can respire.

They make their glucose through a process called photosynthesis.

The vacuole has three main functions in a plant.

It stores water and nutrients.

It helps break down waste products and it also helps to keep the cells firm.

Now the amount of water a vacuole contains can change over time and the best way for you to just to think of this is you might have seen plants when they've wilted if they haven't been watered for a while, which I'm gonna explain why that's the case.

So if we look at the left side of this diagram when a plant has access to lots of water the vacuole fills with water and the cells become turgid.

This means that if you look at the diagram below the plant the cell wall is kind of pushed outwards and it occupies quite a lot of volume the vacuole within the cell.

And this supports the plant.

So when the cells are turgid and the vacuole fills with water it helps support the plant and keep the plant upright.

Whereas if we look on the right hand side of the diagram when a plant doesn't have access to much water the vacuole becomes less full and the cell becomes flacid.

So you can see that the vacuole inside that cell hasn't got as much water within it and therefore it's not exerting quite as much pressure on the cell walls.

And we call that flacid.

And because of that the cells are not able to provide as much support for the plant and therefore the plants start to wilt, which is why the leaves and the stem starts to droop downwards a little bit 'cause not as much support has been provided by the cells.

So the vacuum is actually really, really important in providing support to plants because the cells become turgent, they become full of water.

So the vacuole stores all that water and it pushes out on the cell wall.

Plant cells also have that cell wall to provide structure.

So this links to the idea of cells becoming turgid.

So the cell wall is around the very outmost part of the cell and the cell wall is very strong.

It's made from a substance called cellulose.

And plants need to be well supported as they grow upwards and outwards.

So unlike animals which have skeletons and like vertebrae to keep them upright, plants don't have skeletons, but they do still need to grow upwards and outwards.

So there needs to be a level of support provided to that plant.

And as we said previously, some of that comes from the cells being turgid.

But obviously for the cell to become turgid there's got to be quite a lot of pressure placed upon the outermost layer of the cell.

And that's why the cell wall is there, which withstands that pressure that the vacuole is placing upon that cell.

So cell walls also withstand pressure when the cell becomes turgid.

This table shows the sub-cellular structures that are present in plant and animal cells.

So we're gonna start with cell membrane which is present in both the cell wall, which is only present in plant cells.

The cytoplasm is present in both.

The mitochondria is present in both.

The nucleus is present in both and the ribosomes are present in both, but the vacuole and the chloroplasts are only present in plant cells.

So the three sub-cellular structures that plant cells have that animals don't are the cell wall, the vacuole and the chloroplasts.

Let's check out understanding of this section.

So which of the following do you not find in an animal cell? A, chloroplasts.

B, mitochondria.

C, cytoplasm? That is A the chloroplasts.

Next question.

Where do animal cells get their glucose from? A photosynthesis, B respiration or C, food and drink? This is food and drink, C.

Where do plants get their glucose from? A respiration B, photosynthesis or C, food and drink? Plants get their glucose from photosynthesis.

True or false? Animal cells contain chloroplasts.

So you decide if that's true or false and then justify answer.

A, photosynthesis takes place in the chloroplasts and animals do not photosynthesize or B, respiration takes place in the chloroplasts and all living organisms respire.

Do animals cells contain chloroplasts? No, they do not.

So that is false and the reason why, it's because photosynthesis takes place inside the chloroplasts and animal cells don't photosynthesize.

We get our glucose from food and drink.

Amazing job if you manage to get that right.

We're now ready to move on to our third and final few tasks of the lesson.

So the first part of this task is to complete the table by adding the correct sub-cellular features to each column.

So you've got the sub-cellular features in plants and animal cells and then you've got the sub-cellular features in plant cells only.

So you should have five in plants and animals and three in just the plant cells.

And then for B, can you explain why animals do not need chloroplasts? Pause the video and then press play.

And I will go through the answers with you.

Right then, you get ready to mark and I'll go through it.

So sub-cellular features in plant and animal cells are cell membrane, cytoplasm, ribosomes, nucleus and mitochondria.

It doesn't matter what order you've got those in as long as you've got them in there somewhere.

That is brilliant, well done.

And then the three sub-cellular features only in plant cells are the cell wall, the vacuole and the chloroplasts.

And then B, explain why animals do not need chloroplasts.

Well, this is because plants make their glucose through photosynthesis whereas animals get their glucose through food and drink and therefore they do not need chloroplasts.

If you need to add anything into your answers, pause the video and then you can press play and pick up for the next part.

Okay, last task of the lesson.

So Zeyad is talking to his teacher about plant and animal cells.

What has Zeyad said correctly and what has he got wrong? Write the correct sentences for Zeyad to improve.

So there's quite a bit going on in this question.

So let's just read through what Zeyad had said first.

Zeyad has said animal cells contain chloroplasts because that is where respiration takes place.

Only plant cells contain a cell membrane and a vacuole, but both plant and animal cells contain ribosomes and mitochondria.

So you need to say what Zeyad said correctly and what he's got wrong and you also need to write the correct sentences for Zeyad to improve.

So pause the video now, try your absolute best with this, get as much information as you can and then press play so that I can go through the answers.

Right then.

I'm gonna go through the answers, but I might present mine in a slightly different order to what you've written yours in.

That's okay.

You just find what I'm saying and mark yours as we go.

So Zeyad has correctly said that only plant cells contain a vacuole and that both plant and animal cells contain ribosomes and mitochondria.

So he has got something right when he's been speaking to his teacher.

He has unfortunately though said wrongly that animal cells contain chloroplasts because they don't.

And he's also said that respiration takes place in the chloroplasts, which is not correct.

The correct way of saying that would be that photosynthesis takes place in the chloroplasts and respiration takes place in the mitochondria.

So Zeyad has got a little bit confused about where photosynthesis and respiration take place.

Zeyad has also said that only plant cells contain a cell membrane whereas both plant and animal cells do.

Only plant cells contain a cell wall.

Now I imagine there's a lot of information there you might need to pause the video now.

Just check that you can match up all of your writing to what's on the screen and potentially add a little bit more information in as well if you've forgotten something.

So pause the video and then press play for me to go through the summary of today's lesson.

So this is everything that we've learned today about cellular structures.

We said cells are made up of sub-cellular structures that each have a specific function.

Plant and animal cells both have a nucleus, cell membrane, cytoplasm, mitochondria and ribosomes.

But plant cells also have chloroplasts, vacuole and a cell wall.

Photosynthesis takes place inside the chloroplasts and it makes glucose.

Animal cells get their glucose from food and drink and therefore do not need chloroplasts.

Absolutely amazing work today.

A lot of new information presented in this PowerPoint, but you've done a fabulous job.

There's an exit quiz for you to complete to consolidate some of your understanding.

I'm sure you're gonna do really, really well on that.

I've really enjoyed it and I really look forward to seeing you next time.

Bye.