Understanding Cell Structure and Transport

Hi guys, it's your science teacher here with a video on cell structure and transport. We start off this topic looking at microscopes and over here we have a picture of a light microscope which you will be familiar with using. Now, it's important why we use microscopes in biology. We're looking at things that are really small often, we're looking at cells. and the organelles, the things that make up cells. And there are two main microscopes that you can use in biology, and those are light microscopes, the ones that we use in labs, and also electron microscopes. Now, the electron microscopes are a lot better. They have higher resolution, so you can see a lot smaller things with them. However, they are very expensive and also you can only see dead things under the electron microscope. So light microscopes have an advantage because of the fact they are cheaper. You can see live things, see living cells and you... But... the only problem with them is they are lower resolution. Now when dealing with microscopes also we're looking at tiny tiny things and we need to be able to use prefixes in order to know how small something is. You might see that inside a cell you might be measuring a nucleus which is only one nanometer wide. Now this is just an example but if it was that small You'd need to know that a nanometer is times 10 to the minus 9, micrometer, which is 10 to the minus 6, and millimeter, 10 to the minus 3. After you have looked at something under a microscope, you might want to work out the actual size of the image. And to do that, you need to use a calculation triangle. Using calculation triangles is a real skill, so I'm going to quickly show you how to use a calculation triangle. So if you wanted to calculate the real size of the object, which is usually what you do with a microscope, what you do is you cover it up with your hand or scribble it in and you could do real size equals. And then you can see size of image is above magnification. So that's on top size of image over magnification. If you were interested in calculating the magnification, how much you'd zoomed in, you could scribble in magnification or cover it up with your hands, and you could say magnification equals size of image over real size of object. And lastly, if you were wanting to calculate the size of the image on... On the slide, you scribble that in and size of image equals magnification times the real size because they're next to each other. When we use microscopes, we can observe very tiny things and we can actually look at cells. There are two types of cell you need to know about. You need to know about animal cells and plant cells. So here on the left we have our animal cell and on the right we have a generic plant cell. Now this might be more complex than the original model of a cell that you looked at in Key Stage 3. There's a few more extra organelles that you might need to look at. So let's go through each organelle and what they do. So this big black object here is known as the nucleus. And what the nucleus does is it holds the DNA for the cell. It's basically the brain of the cell. And around the outside of your cell, around the outside, you have the cell membrane. And the job of the cell membrane is to control. what goes in and out of your cell. You'll notice there's a strange red looking object as well in our cell and that is our mitochondria and that's the site of respiration. and is what gives our body energy. You also see these tiny dots as well in your cells, and that is called ribosomes, and that is the site of protein synthesis. And all of this cell is inside this gooey substance known as cytoplasm, and the cytoplasm is where all the chemical reactions for the cell take place. I've added labels on the plant cell to show where there is overlap, where the nucleus, mitochondria and cell membrane are in a plant cell as well. But there's also three different organelles that aren't found in animal cells but are found in plant cells. And the first one we're going to look at is the biggest one that goes around the outside, which is called the cell wall. And basically that... gives a plant cell its rigidity, it makes it strong and animal cells don't need the cell wall to go round their cells. Now the next one that we're going to look at is this big grey object and that is what's known as a vacuole and the vacuole is where sugars are stored and also It also gives this plant cell more structure as well, so it keeps the plant cell really turgid. And the last organelle we're going to look at is this green one, which is known as the chloroplast. And this is the cytophotosynthesis. So the chloroplasts contain chlorophyll, which absorb the sunlight. and they use that energy to convert water and carbon dioxide into oxygen and glucose, which they then use for respiration. Now, animal and plant cells are both types of eukaryotic cells as they are multicellular. Another type is multicellular, you could say fungi as well, they're multicellular, because all of the cells... work together. However, that's not always the case. You have prokaryotic cells like bacteria and also algae and microplasma. And here I have a type of bacteria. And this type of bacteria is actually called Eugelina. And you might already see some differences between plants and animal cells and this bacteria cell. I think the most... striking distinguishing factor is this tail which is called a flagellum and it can use that to swim around also it doesn't have a central nucleus it has a spherical nucleoid in which all the DNA is stored it also does have some chloroplasts just like plant cells so it can carry out photosynthesis to provide it with energy and with having chloroplast it also needs to have a vac to store sugars that it makes. Now you can often tell whether you've got a prokaryotic cell by if it has any distinguishable features like either a flagellum or a nucleoid you can say it's definitely going to be a prokaryotic cell and not a eukaryotic cell. Earlier we looked at really simple animal cells. and now we're going to look at what happens when they become specialised. We need specialised cells in our body because we have different areas and we need cells that can carry out a certain type of function. One type of cell that we have in our bodies are red blood cells and this is actually a red blood cell down here. And you'll see it looks different to the animal cells that we looked at earlier. One of the key differences is the fact that it's got no nucleus. The reason why the red blood cells don't have a nucleus is so they have more space to carry oxygen. And that's basically how they're so good for their job is the fact that they have this bi-concave shape, the donut shape, so that they can carry lots of oxygen and they don't waste any space so that they can bind to as much oxygen as possible through their haemoglobins. This strange looking cell next to the red blood cell is actually a white blood cell. And the job of the white blood cell is to fight off infections and it's perfectly adapted to this by being in a regular shape. And the fact that it's a regular shape means it can get to the site of the infection really quickly and also it can engulf bacteria or virus. Here we've got some muscle cells and muscle cells are perfectly adapted by having protein fibers which make them contract when you need to lift something up or you need to tense. And also the fact that they contain lots of mitochondria because of the fact you need lots of energy in your muscles. if you are constantly contracting them to move. Remember that mitochondria is the site of respiration and how energy is released. The last one that we're going to look at is sperm cells. And sperm cells have lots of different adaptations. Perhaps the most obvious adaptation of a sperm cell is the fact that it has a tail, and that is obviously so it can swim. to the egg. This is actually an egg cell and you can see how much larger the egg cell is than the sperm cell and that's quite significant as well. Also with a sperm cell it has in its head this chemical called Acrosome and the reason why it has Acrosome is so that it can break down the barrier towards the egg because the egg contains Sperm cells also contain acrosome in the head and that helps break down the lining of the egg cell so that the sperm cell can enter. And also like with the muscle cells it has a store of mitochondria so that it can have lots of energy. Obviously it's got to swim. So that's why it has lots of mitochondria. Just like with animal cells, plant cells specialise as well to be adapted for their specific role. Here I've got three different plant cells that I'm going to show you. The first one I'm going to show you is called xylem cells, which you might not have heard of. They're not very common in Key Stage 3, however we look at them for GCSE syllabus. And the xylem cells are these kind of... tube like cells running down the plant here and what they basically do is they transport water and minerals from the roots All the way up to the leaves now. How is xylem perfectly adapted for this? It's perfectly adapted because of the fact it contains dead cells and The reason why it can contain dead cells and not alive cells the dead cells are actually called lining. The reason why it can be made of dead cells is because of the fact it's a passive process. It doesn't require any energy. So why waste living cells making energy when you can use dead cells? Perhaps some of the most complex cells in a plant is the phloem cells. And the phloem basically transports... the products of photosynthesis glucose up and down the plant to where it needs to go. The reason why you might want glucose going down the plant is because if the plant needs to make seeds or needs more energy for active transport in the roots, then the glucose needs to be transported down to the roots. Now because it's going both ways, This is not a passive process anymore and phloem actually contain a lot of mitochondria. That's one of the adaptations because energy is needed in order to open and close these sieve tubes. And these sieves basically act by opening and closing, letting substances move either up or down. One more cell. that I'm going to talk about is this one over here and this looks really strange amongst all the other ones the reason why I'm using actual images is because sometimes this actually comes up in GTSA and they like to use actual image and also I think it's more interesting than looking at recreations drawn by me so if we look at this cell this is a root hair cell and you'll notice compared to all the other cells it is much larger and it has a larger surface area. The reason why it has such a large surface area is so that it can get more water. through osmosis and more minerals through active transport. In addition to this, just like with the phloem, the root hair cells do contain lots of mitochondria because of the fact energy is needed for active transport because you're going against the concentration gradient. And we're going to talk about active transport and what that actually is in a couple of slides time. We are now going to look at transport in cells and how different materials move around plants and animals. The first process is known as diffusion. And you've probably heard of diffusion before. And diffusion is a passive process, meaning it does not require any energy. All it needs is a concentration gradient. This is showing... diffusion happening in a liquid. It's showing that the food colouring dye is moving from an area of high concentration to an area of low concentration and spreading out. Now, you might also notice there's a bit of difference between the two glasses. One of them is happening much quicker than the other one. The reason for that is because there is a higher concentration gradient and also the fact... that it is hotter in this glass so it's also hotter and has a higher concentration gradient and that can affect the rate of diffusion now how does diffusion work in cells so we've said that it's the movement from a high to a low concentration and the fact that it doesn't require energy but what how does that apply to cells basically let's look at this oxygen set oxygen entering an animal cell. Well, the animal cell has a few oxygen molecules in it, but there is a lot more oxygen on the outside. And because of the fact there's a lot more oxygen on the outside, it's going to do exactly what's happening down here, and it will diffuse into the cell, okay? It will move into it until there is about a 50-50. And so, It doesn't require any energy for the cell to allow the oxygen in, it's a passive process. And it also works the other way, getting carbon dioxide out of the cells from respiration, and carbon dioxide will move out of the cell just in the same way diffusion caused it to move in. Osmosis is very similar to diffusion in the fact that it's also a passive process, meaning it does not require any energy. However, the only real difference is the fact it involves water molecules and only water molecules and the fact that the water molecules have to pass through a passive, partly permeable membrane. And that basically means that it will partially absorb water. Let's have a look at what osmosis looks like. Here we've got a... barrier going from an area of high concentration of water to an area where there is zero concentration of water and look they'll start to move over over time through that partially permeable membrane because of osmosis until there is about a 50 50 split the last process i want to talk to you about is active transport and this is no longer a passive process this requires energy to make it happen. And wherever cells need energy, they need mitochondria, okay? They need mitochondria to supply that energy through respiration. Here is a root hair cell, okay? And the red is showing the concentration of ions and minerals inside that cell. Now, if diffusion was to occur, then actually the ions and minerals would move. out of the plant cell. However, it wants to keep hold of them. And actually, it's a bit greedy. It wants more to actually enter the cell. It wants all of these ions and minerals to go in. It's gold for this cell. They need them ions. They need them minerals in order to grow and reproduce. So what it needs to do is it needs to go against the concentration gradient in order to get them ions inside that root hair cell and to the parts of the plant that needs it. I hope you enjoyed watching this screencast. Please remember to like and subscribe to my channel. I've had a great response so far from you guys. Keep, keep working hard. Thank you.

And there are two main microscopes that you can use in biology, and those are light microscopes, the ones that we use in labs, and also electron microscopes. Now, the electron microscopes are a lot better. They have higher resolution, so you can see a lot smaller things with them.

However, they are very expensive and also you can only see dead things under the electron microscope. So light microscopes have an advantage because of the fact they are cheaper. You can see live things, see living cells and you...

But... the only problem with them is they are lower resolution. Now when dealing with microscopes also we're looking at tiny tiny things and we need to be able to use prefixes in order to know how small something is.

You might see that inside a cell you might be measuring a nucleus which is only one nanometer wide. Now this is just an example but if it was that small You'd need to know that a nanometer is times 10 to the minus 9, micrometer, which is 10 to the minus 6, and millimeter, 10 to the minus 3. After you have looked at something under a microscope, you might want to work out the actual size of the image. And to do that, you need to use a calculation triangle. Using calculation triangles is a real skill, so I'm going to quickly show you how to use a calculation triangle.

So if you wanted to calculate the real size of the object, which is usually what you do with a microscope, what you do is you cover it up with your hand or scribble it in and you could do real size equals. And then you can see size of image is above magnification. So that's on top size of image over magnification.

If you were interested in calculating the magnification, how much you'd zoomed in, you could scribble in magnification or cover it up with your hands, and you could say magnification equals size of image over real size of object. And lastly, if you were wanting to calculate the size of the image on... On the slide, you scribble that in and size of image equals magnification times the real size because they're next to each other. When we use microscopes, we can observe very tiny things and we can actually look at cells.

There are two types of cell you need to know about. You need to know about animal cells and plant cells. So here on the left we have our animal cell and on the right we have a generic plant cell.

Now this might be more complex than the original model of a cell that you looked at in Key Stage 3. There's a few more extra organelles that you might need to look at. So let's go through each organelle and what they do. So this big black object here is known as the nucleus.

And what the nucleus does is it holds the DNA for the cell. It's basically the brain of the cell. And around the outside of your cell, around the outside, you have the cell membrane.

And the job of the cell membrane is to control. what goes in and out of your cell. You'll notice there's a strange red looking object as well in our cell and that is our mitochondria and that's the site of respiration. and is what gives our body energy.

You also see these tiny dots as well in your cells, and that is called ribosomes, and that is the site of protein synthesis. And all of this cell is inside this gooey substance known as cytoplasm, and the cytoplasm is where all the chemical reactions for the cell take place. I've added labels on the plant cell to show where there is overlap, where the nucleus, mitochondria and cell membrane are in a plant cell as well. But there's also three different organelles that aren't found in animal cells but are found in plant cells. And the first one we're going to look at is the biggest one that goes around the outside, which is called the cell wall.

And basically that... gives a plant cell its rigidity, it makes it strong and animal cells don't need the cell wall to go round their cells. Now the next one that we're going to look at is this big grey object and that is what's known as a vacuole and the vacuole is where sugars are stored and also It also gives this plant cell more structure as well, so it keeps the plant cell really turgid.

And the last organelle we're going to look at is this green one, which is known as the chloroplast. And this is the cytophotosynthesis. So the chloroplasts contain chlorophyll, which absorb the sunlight.

and they use that energy to convert water and carbon dioxide into oxygen and glucose, which they then use for respiration. Now, animal and plant cells are both types of eukaryotic cells as they are multicellular. Another type is multicellular, you could say fungi as well, they're multicellular, because all of the cells... work together.

However, that's not always the case. You have prokaryotic cells like bacteria and also algae and microplasma. And here I have a type of bacteria. And this type of bacteria is actually called Eugelina.

And you might already see some differences between plants and animal cells and this bacteria cell. I think the most... striking distinguishing factor is this tail which is called a flagellum and it can use that to swim around also it doesn't have a central nucleus it has a spherical nucleoid in which all the DNA is stored it also does have some chloroplasts just like plant cells so it can carry out photosynthesis to provide it with energy and with having chloroplast it also needs to have a vac to store sugars that it makes.

Now you can often tell whether you've got a prokaryotic cell by if it has any distinguishable features like either a flagellum or a nucleoid you can say it's definitely going to be a prokaryotic cell and not a eukaryotic cell. Earlier we looked at really simple animal cells. and now we're going to look at what happens when they become specialised. We need specialised cells in our body because we have different areas and we need cells that can carry out a certain type of function. One type of cell that we have in our bodies are red blood cells and this is actually a red blood cell down here.

And you'll see it looks different to the animal cells that we looked at earlier. One of the key differences is the fact that it's got no nucleus. The reason why the red blood cells don't have a nucleus is so they have more space to carry oxygen. And that's basically how they're so good for their job is the fact that they have this bi-concave shape, the donut shape, so that they can carry lots of oxygen and they don't waste any space so that they can bind to as much oxygen as possible through their haemoglobins.

This strange looking cell next to the red blood cell is actually a white blood cell. And the job of the white blood cell is to fight off infections and it's perfectly adapted to this by being in a regular shape. And the fact that it's a regular shape means it can get to the site of the infection really quickly and also it can engulf bacteria or virus.

Here we've got some muscle cells and muscle cells are perfectly adapted by having protein fibers which make them contract when you need to lift something up or you need to tense. And also the fact that they contain lots of mitochondria because of the fact you need lots of energy in your muscles. if you are constantly contracting them to move. Remember that mitochondria is the site of respiration and how energy is released.

The last one that we're going to look at is sperm cells. And sperm cells have lots of different adaptations. Perhaps the most obvious adaptation of a sperm cell is the fact that it has a tail, and that is obviously so it can swim. to the egg. This is actually an egg cell and you can see how much larger the egg cell is than the sperm cell and that's quite significant as well.

Also with a sperm cell it has in its head this chemical called Acrosome and the reason why it has Acrosome is so that it can break down the barrier towards the egg because the egg contains Sperm cells also contain acrosome in the head and that helps break down the lining of the egg cell so that the sperm cell can enter. And also like with the muscle cells it has a store of mitochondria so that it can have lots of energy. Obviously it's got to swim.

So that's why it has lots of mitochondria. Just like with animal cells, plant cells specialise as well to be adapted for their specific role. Here I've got three different plant cells that I'm going to show you.

The first one I'm going to show you is called xylem cells, which you might not have heard of. They're not very common in Key Stage 3, however we look at them for GCSE syllabus. And the xylem cells are these kind of... tube like cells running down the plant here and what they basically do is they transport water and minerals from the roots All the way up to the leaves now. How is xylem perfectly adapted for this?

It's perfectly adapted because of the fact it contains dead cells and The reason why it can contain dead cells and not alive cells the dead cells are actually called lining. The reason why it can be made of dead cells is because of the fact it's a passive process. It doesn't require any energy.

So why waste living cells making energy when you can use dead cells? Perhaps some of the most complex cells in a plant is the phloem cells. And the phloem basically transports... the products of photosynthesis glucose up and down the plant to where it needs to go. The reason why you might want glucose going down the plant is because if the plant needs to make seeds or needs more energy for active transport in the roots, then the glucose needs to be transported down to the roots.

Now because it's going both ways, This is not a passive process anymore and phloem actually contain a lot of mitochondria. That's one of the adaptations because energy is needed in order to open and close these sieve tubes. And these sieves basically act by opening and closing, letting substances move either up or down.

One more cell. that I'm going to talk about is this one over here and this looks really strange amongst all the other ones the reason why I'm using actual images is because sometimes this actually comes up in GTSA and they like to use actual image and also I think it's more interesting than looking at recreations drawn by me so if we look at this cell this is a root hair cell and you'll notice compared to all the other cells it is much larger and it has a larger surface area. The reason why it has such a large surface area is so that it can get more water. through osmosis and more minerals through active transport.

In addition to this, just like with the phloem, the root hair cells do contain lots of mitochondria because of the fact energy is needed for active transport because you're going against the concentration gradient. And we're going to talk about active transport and what that actually is in a couple of slides time. We are now going to look at transport in cells and how different materials move around plants and animals. The first process is known as diffusion.

And you've probably heard of diffusion before. And diffusion is a passive process, meaning it does not require any energy. All it needs is a concentration gradient. This is showing...

diffusion happening in a liquid. It's showing that the food colouring dye is moving from an area of high concentration to an area of low concentration and spreading out. Now, you might also notice there's a bit of difference between the two glasses. One of them is happening much quicker than the other one.

The reason for that is because there is a higher concentration gradient and also the fact... that it is hotter in this glass so it's also hotter and has a higher concentration gradient and that can affect the rate of diffusion now how does diffusion work in cells so we've said that it's the movement from a high to a low concentration and the fact that it doesn't require energy but what how does that apply to cells basically let's look at this oxygen set oxygen entering an animal cell. Well, the animal cell has a few oxygen molecules in it, but there is a lot more oxygen on the outside. And because of the fact there's a lot more oxygen on the outside, it's going to do exactly what's happening down here, and it will diffuse into the cell, okay? It will move into it until there is about a 50-50.

And so, It doesn't require any energy for the cell to allow the oxygen in, it's a passive process. And it also works the other way, getting carbon dioxide out of the cells from respiration, and carbon dioxide will move out of the cell just in the same way diffusion caused it to move in. Osmosis is very similar to diffusion in the fact that it's also a passive process, meaning it does not require any energy. However, the only real difference is the fact it involves water molecules and only water molecules and the fact that the water molecules have to pass through a passive, partly permeable membrane.

And that basically means that it will partially absorb water. Let's have a look at what osmosis looks like. Here we've got a... barrier going from an area of high concentration of water to an area where there is zero concentration of water and look they'll start to move over over time through that partially permeable membrane because of osmosis until there is about a 50 50 split the last process i want to talk to you about is active transport and this is no longer a passive process this requires energy to make it happen. And wherever cells need energy, they need mitochondria, okay?

They need mitochondria to supply that energy through respiration. Here is a root hair cell, okay? And the red is showing the concentration of ions and minerals inside that cell. Now, if diffusion was to occur, then actually the ions and minerals would move. out of the plant cell.

However, it wants to keep hold of them. And actually, it's a bit greedy. It wants more to actually enter the cell. It wants all of these ions and minerals to go in. It's gold for this cell.

They need them ions. They need them minerals in order to grow and reproduce. So what it needs to do is it needs to go against the concentration gradient in order to get them ions inside that root hair cell and to the parts of the plant that needs it. I hope you enjoyed watching this screencast. Please remember to like and subscribe to my channel.

I've had a great response so far from you guys. Keep, keep working hard. Thank you.

Transcript for:Understanding Cell Structure and Transport

Transcript for:
Understanding Cell Structure and Transport