Lesson video

- Hello and welcome to today's "Oak Academy Science Session." My name is Mrs. Bowes.

I'm really, really looking forward to teaching you to make sure that you're ready to learn.

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

The title of today's lesson is cell structures and the outcome is to identify the sub-cellular structures of plant and animal cells and describe their function.

This is a science lesson and it comes from the key stage three topic called Cells.

If you need to pause the lesson now to write down the title, please do and then press Play and we will carry on.

The key words for today's lesson are sub-cellular.

Sub-cellular structures are smaller parts that make up a cell.

So if you have one cell, there are smaller parts within that cell and they are the sub-cellular structures.

Synthesis means to make something and photosynthesis is a process that plants use to make glucose.

Glucose is a sugar.

Now notice here that the word photosynthesis has got the word synthesis within it, and that's because plants are making glucose.

The outline of our lesson on cell structures is as follows.

The first thing we're going to look at is the sub-cellular structures of animal cells.

Then we're going to look at the sub-cellular structures of plant cells and then finally, we are going to compare the structure of plant and animal cells.

Let's begin with, let's have a look at some animal cells.

So, here are three pictures.

What do you think those three pictures are showing? Now, some of them actually look very, very cool.

They're actually images that show different cells viewed under a microscope.

So the first picture, the one that's sort of green and black, that is showing you some plant cells.

Then the pink one is showing you some onion cells and then the final picture is some fungi and all of those have been viewed with a microscope.

Now, why do you think that they look different? Well, some of them have been stained to make them a specific colour, but also you'll notice they are different shapes and different sizes, and that's because each of the cells have different jobs, different functions and because of that, they have different shapes and different sub-cellular structures within them.

Now, the reason that we know what cells look like is because of this piece of equipment here, which is a microscope.

And we use microscopes to magnify cells and look at them in more detail.

So we would be unable to look at a plant and visualise all of the cells within that plant, just by looking with our eyes we have to magnify those images.

To magnify means to make something appear bigger, so we have magnified the plant cells and then we can see what they look like.

Same with animal cells and that's how we now know the sub-cellular structures that are contained within cells.

So, cells are made up of sub-cellular structures.

So, what does that word actually mean? Well, sub means one small part of a larger thing and cellular is a living cell.

So, if you put both of those things together, sub-cellular structures are smaller parts that make up a cell.

We are now going to look at some of those sub-cellular structures, within animal cells.

So, the picture that's on the screen now is showing you a typical animal cell and you can see that it's got lots of smaller structures, contained within it.

These are the sub-cellular structures.

Now, the first one we're going to look at is the nucleus, which is labelled here.

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

The cytoplasm is a jelly-like substance where the chemical reactions take place and the cytoplasm surrounds, all of the sub-cellular structures within the cell.

The cell membrane surrounds the cell and controls what enters and exits that cell.

So, the cell membrane is, we call it permeable, so it's semipermeable.

It allows some substances in and some substances out, but doesn't let some in and out, so it controls what enters and exits the cell.

Then we've got the mitochondria.

This is where aerobic respiration occurs and it releases energy.

So, living cells will be respiring, which releases energy for other cellular processes and this respiration occurs inside the mitochondria.

The ribosomes, are one of the smallest sub-cellular structures and this is where protein synthesis takes place.

Remember, synthesis means to make, so the ribosomes make proteins.

It's where proteins are synthesised.

Let's see how much of that we have remembered.

So, we're gonna ask some questions.

There will be some optional responses or you might have to come up with a response yourself.

Give it your best go.

Doesn't matter if we get anything wrong.

The first question is which structure is this arrow pointing to? A, cytoplasm, B, nucleus, C, cell membrane or D, mitochondria.

This is C, the cell membrane.

Which sub-cellular structure is the arrow pointing to here? A, the nucleus.

B, the mitochondria, C, the cytoplasm or D, the ribosome.

This one is B, the mitochondria, which sub-cellular structure is this arrow pointing towards? A, the mitochondria.

B, the ribosome, C, the nucleus or D, the cell membrane.

This is C, the nucleus.

That's where all the DNA is held.

And finally which sub-cellular structure is the arrow pointing towards on the diagram? A, mitochondria, B, ribosome, C, nucleus or D, cell membrane.

This is B, the ribosome.

Absolutely amazing if you recognised all of those features.

Now, a little bit harder here.

You have to remember the names of the sub-cellular structures yourself.

So, complete the two missing labels on this diagram.

Some of it's already been labelled for you, but what are the missing two? You should have the cell membrane on the outer part of the cell and that is the nucleus.

Make sure you've got those the right way round.

Really well done if you did remember that.

And complete the two missing labels on this diagram.

We have got the mitochondria and the ribosomes.

Check your spelling there, 'cause they are slightly more difficult, but absolutely amazing if you did remember those, that's really, really good work.

We are ready now to move on to our first task.

So, your job is to label the sub-cellular structures of this animal cell.

Pause the video, give it your best go and then press Play and I will go through the answers with you.

So, here are the answers.

You should have the cell membrane, the nucleus, the mitochondria, the cytoplasm and the ribosome.

If you need to pause the video to correct anything, check your spellings and then press Play when you're ready for me to carry on with the next part of the lesson.

So, now we know the sub-cellular structures in an animal cell.

We're going to move on to the sub-cellular structures of a plant cell.

Now just to begin with, some of the sub-cellular structures in plant cells are the same as animal cells.

There are actually quite a few that are exactly the same.

The picture that is on the slide now is showing you a typical plant cell.

This is actually a palisade cell, but it is a typical plant cell.

So, one that we've already come across in our animal cell is the nucleus.

Remember, the nucleus contains the genetic information, the DNA and it controls the cells activities.

Then we've got the cell membrane that was also in an animal cell which surrounds the cell and controls or enters and exits the cell.

We've also got the cytoplasm, which was in an animal cell and this is the gel-like substance where chemical reactions take place.

We have mitochondria like the animal cell where aerobic respiration and energy is released.

We also have the ribosomes that really small sub-cellular structure where the proteins are the synthesised.

So, those are the common parts of cells that both animal and plant cells have.

But now we're going to talk about things, sub-cellular structures that are different.

So, the plant cell also has a cell wall.

So, the cell membrane was the most outmost layer of an animal cell and a plant cell has a cell membrane, but on the outside of that, it then has this cell wall and it contains a substance called cellulose and that provides strength and support to the plant.

You've got to think that in animals, we've got skeletons which help keep us upright and provide support.

Plants do not have skeletons and they rely on their cells and structures within the plant to provide that support.

And the cell wall is one of those structures.

They also have something called chloroplasts.

Chloroplasts contain a green pigment called chlorophyll and this is where photosynthesis takes place.

Now remember from our key words that photosynthesis is a process where plants make their own glucose.

Animal cells do not need chloroplasts, because we get our glucose from food.

And then finally they've got a vacuole, which is this big structure in the middle and that contains a substance called sap, which help keeps a cell firm.

So, these are all the sub-cellular structures in a plant cell.

If we've got a cell wall, cell membrane, chloroplast, vacuole, ribosome, mitochondria, cytoplasm and nucleus.

So, the three additional structures are the cell wall, the chloroplasts, and the vacuole.

Right, we should be ready now to answer some questions.

So, nice and easy to begin with.

Which sub-cellular structure is the arrow pointing towards? A, chloroplast, B, nucleus or C, ribosome? This is A, the chloroplasts.

Remember that is where photosynthesis takes place, only found in plant cells.

Which sub-cellular structure is this arrow pointing towards A, cell membrane, B, the cytoplasm or C, the cell wall.

This is C, the cell wall.

Next question, what is the function of the cell membrane? A, contains cellulose to provide strength and support.

B, a gel-like substance where chemical reactions occur or C controls or enters and exits the cell.

This is C, the cell membrane controls or enters and exits the cell.

Well done if you remember that.

Next one.

What is the function of the nucleus? A, contains DNA that controls the cells activities.

B, protein synthesis occurs here, or C, the site of aerobic respiration.

This is A, it contains the DNA that controls the cells activities.

And now what is the function of vacuole? A, the site of aerobic respiration.

B, protein synthesis or C, contains sap which keeps the cell firm.

This is C, it does contain sap, which keeps the cell firm.

Really good job if you manage to get that.

And then here, protein synthesis takes place in the? So, you tell me which sub-cellular structure is where protein synthesis occurs.

Have we got this? It's the ribosomes.

And then photosynthesis takes place in there? This is the chloroplasts.

So, remember, ribosomes are in both animal and plant cells but chloroplasts are unique to plants.

We are now ready to move on to task two.

So, the first part of task two is that you need to label the features of this plant cell.

Pause the video, give it your best go and then press Play and I will go through the answers.

Right then, let's get ready to mark it.

So, we have the cell wall on the outside and then on the inside is a cell membrane.

We've got the chloroplast there.

Then that is the vacuole.

So the cell wall, chloroplasts and vacuole are specific to plant cells.

Then we've got the ribosomes, the mitochondria, the cytoplasm is the jelly-like substance surrounding all the others.

And then we've got the nucleus, containing the DNA at the top.

Absolutely amazing if you manage to get all of those right.

We're now going to move on to the second part of our task.

So, you now need to complete this table to describe the function of each structure.

So, you've got the structure in one column and then the function.

If you've been given the name of the structure, your job is to write a sentence, which says what the function is.

If you've been given the function, you need to write the name of that structure.

So, pause the video and then press Play when you are ready for me to go through the answers.

Well, hopefully we did a good job of that.

Make sure you're marking this as we go along.

So, the first structure is cytoplasm and the function of the cytoplasm is that it's a jelly-like substance where chemical reactions occur.

Then the next one, the function was that it contains the DNA that controls cells activities.

That is the nucleus.

Where protein synthesis occurs is the ribosomes.

The mitochondria function is where aerobic respiration occurs.

The chloroplast function is where photosynthesis takes place.

The structure that controls what enters and exits the cell is the cell membrane.

The function of the vacuole is that it contains sap that keeps the cell firm and cell wall provides strength and structure to the cell.

There's a lot of information in that table, so that is really, really amazing if you've managed to get lots of that right.

If you need to pause a video to add anything in, please do and then press Play and we'll carry on with the rest of the lesson.

So, we know the structure of both animal and plant cells and now we're just gonna spend some time, comparing the structure of plant and animal cells.

As I've said before, there are three sub-cellular structures plant cells contain that animal cells do not.

So, here on the left we've got an animal cell and on the right we've got our plant cell.

There are some common features, which I'm gonna go through first.

So, the common sub-cellular structures are, both in plants and animal cells.

The cell membrane controls what enters and exits the cell.

The nucleus contains the DNA and controls the cell's activities.

The cytoplasm is the jelly-like substance where chemical reactions take place.

The ribosomes are where protein synthesis occurs and the mitochondria is where aerobic respiration occurs.

So, these are the five common sub-cellular structures in plant and animal cells; cell membrane, nucleus, cytoplasm, ribosomes and mitochondria.

There are three sub-cellular structures that are only found in plants.

They're not found in animal cells.

The first one is the chloroplasts.

Remember, this is where photosynthesis takes place.

Then we've got the cell wall that provides structure and strength to the plants.

And then we've got the vacuole, which contains sap which keeps the cell firm.

Now, there is a reason why animal cells, don't have those structures.

The cell wall I spoke about previously.

Humans have a skeleton which provides support to us.

Plants do not have a skeleton, so each of their cells needs to have quite a lot of water in and the cell wall needs to withstand that pressure and that also links to why the cells, also have vacuole as well to keep the cell firm, so that the plant can have more support.

We're gonna talk about the chloroplasts now in more detail.

So, why do plants need chloroplasts but animal cells don't? Well, plants use a sun's energy to produce glucose during photosynthesis.

And photosynthesis takes place in the chloroplasts.

Animals get their glucose from eating food, so they don't need chloroplasts, because the glucose gets into their body when they eat.

Plants don't eat food, they have to make their own glucose and they make that glucose, through a process called photosynthesis.

Okay, last few checks for understanding, which of the following do plants cells and animal cells, both contain? A, chloroplast, B, cytoplasm, C, cell wall.

So, the structure that both plants and animals contain is B, the cytoplasm.

Which sub-cellular structure is not found in animal cells.

A, vacuole, B, ribosome, C, mitochondria.

This is A, the vacuole.

Where do animal cells get or animals, sorry, get their glucose from? A, photosynthesis.

B, food and drink, or C respiration.

B, food and drink.

And plants make glucose through which process? A, photosynthesis, B, fermentation or C, respiration.

This is A, photosynthesis.

We are now ready to move on to our third and final task.

And this is in two parts.

So, part A is describe the differences in structure between plant and animal cells.

You should refer to the sub-cellular structures, within your answers.

Pause the video and give it your best go.

When you are ready to start, press Play.

I'll go through the answers with you.

Let's go through the answers.

So, both plant and animal cells, contain a cell membrane, nucleus, cytoplasm, mitochondria and ribosomes.

However, a plant cell also contains chloroplasts, a vacuole and a cell wall, which are not present in an animal cell.

Make sure that you've got five common features and three sub-cellular structures that are only found in plant cells.

Amazing job if you manage to do that.

Well done.

Part B of this task is why does a plant cell need chloroplasts, but animal cells do not? So, have a go at this, pause the video and then press Play when you are ready to continue.

Okay, so we should have written that chloroplasts are where photosynthesis takes place.

Plants photosynthesize to produce glucose, but animal cells do not photosynthesize.

And then we could have said that animal cells get their glucose from food and drink.

If you need to pause a video to add anything to your answer, please do.

You've done such a brilliant job this session.

Really, really big well done.

I'm just gonna do a really quick summary now of everything that we've learned.

The first thing we said was that sub-cellular structures are smaller parts of the cell.

We said animal implant cells share some common structures, but there are also some differences.

The different sub-cellular structures, have different functions.

Both animal and plant cells have a cell membrane, nucleus, cytoplasm, mitochondria and ribosomes.

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

There's lots of new information in this lesson and I think you've done a brilliant job, remembering most of it.

There's an exit quiz for you to have a go out at the end of the lesson, just to consolidate some of that knowledge, but a really, really, really big well done and I look forward to seeing you next time.

Bye.