Cells

Let’s take a look at how to observe cells under a microscope.

No prizes for guessing the first thing you’ll need — a microscope.

But don’t worry if you don’t have one of your own, ask your school if they have one you can use.

Then you’ll need an onion, that’s where you’ll get your plant cells. Some food colouring, blue or green works best, a cotton bud and a mouth. Probably best to use your own!

Let’s begin by looking at some plant cells.

Cut a small chunk from your onion — be careful with knives, ask an adult if you need help.

Peel a thin layer of that chunk and put it on your slide. This is what’s called the epidermis.

Using a drop of food colouring, stain the layer so you can see the cells.

Pop a cover slip on the slide and then put the slide onto the microscope.

Take a look.

Check out that strong cell wall structure! It is solid so that it keeps the plant’s shape and structure.

But this experiment isn’t over. You can look at some animal cells too.

Grab a fresh slide and pop a drop of your food colouring on there.

Take your cotton bud and rub the inside of your cheek — told you you’d need a mouth!

Transfer the cheek cells to the slide by rubbing the swab all over it.

Drop the cover slip on the slide and stick it on the microscope.

Go find those animal cells.

Unlike the plant cells, animal cells are soft and fleshy. Animals don’t need cells to keep their structure — that’s what skeletons are for.

And there you have it!

TILLY: My name's Tilly, I'm a butcher. I cut and sell meat over the counter to the public.

Biology was probably my favourite subject, funnily enough.

I've always been fascinated with bodies, with animals, with humans, how they work, what they're made up of.

Meat is composed of animal cells: the cell membrane, the cytoplasm, and the nucleus. Meat feels squishy, very malleable.

ADAM: My name is Adam, and I work for a fruit and vegetable business.

Plant cells have a rigid cell structure. They are made up of a cell wall, cell membrane, cytoplasm, vacuole, nucleus, and chloroplasts.

Plants feel firm because of their cellular walls. This is why fruit and vegetables have a nice crunch and firmness to them.

TILLY: Once you take the bones out of the meat itself, it's very easy to tie it up and change the shape of it.

ADAM: Some fruit and vegetables have really strong cells, such as root vegetables: carrots, fruits like apples. When they're well watered, the vacuoles are firm. But when the plant starts to lose water, we start to see the plants going wilted and droopy. We use temperature and humidity to keep the fruit and vegetables fresh.

Tilly: The best thing about being a butcher, I would say for me, is talking about how to cook meat, how it's raised, and seeing people choose to buy ethical and sustainable meat.

Adam: Best thing about my job is definitely eating the fruit and vegetables every day.

This is how you make a model plant cell.

There are a few things you'll need:

A plastic box, a small sealable sandwich bag filled with water, cling film, some peas -frozen or otherwise, some water with green food colouring - if you've got any, and a trusty grape.

Line the plastic box with cling film.

Pop the sealed plastic bag in.

Spread the peas generously.

Get the grape in there.

And finally, top it up with the coloured water.

Then you'll have a model plant cell with all of its parts:

Cell wall, which keeps everything together, Cell membrane, which surrounds the cytoplasm. Vacuole, the space within the cytoplasm that contains fluids and nutrients. Nucleus, which contains the cell's genetic material. Cytoplasm, where the cell's chemical reactions happen. Chloroplasts, where photosynthesis takes place.

So there you have it — the building blocks of plant life!

How multicellular organisms are organised.

Multicellular organisms are organised into increasingly complex parts.

Cells are the building blocks of life.

Tissue is made when specialised cells with the same function group together. For example, millions of muscle cells make up muscle tissue.

An organ is made from two or more tissues, which all work together to do a particular job, like the heart in animals or a leaf in a plant.

An organ system is made of a group of organs which all work together to do a particular job, such as the nose, trachea, bronchi and lungs, which all make up the gas exchange system.

PRESENTER 1: Yeah, so one of the systems in the human body is the digestive system. Ours is simpler than some other animals, like cows and deer have multiple stomachs, we just have the one.

PRESENTER 2: So as you can see, there are lots of tissues and organs that make up our digestive system. But what's the difference between them?

PRESENTER 1: So, yeah, these are some key things on your school syllabus. Firstly, you need to know that a tissue is a group of cells in the same place all doing the same thing. There are loads of cells in your mouth making saliva. Imagine if the saliva-making tissue all disappeared. You'd have the driest mouth in the world.

PRESENTER 2: I sometimes get that when I'm nervous on television. But anyway, how about an organ, then?

PRESENTER 1: So organs are these things here, like the stomach and liver. They do an overall job. There's an amazing organ called a spleen that can help you hold your breath underwater for longer if you have a really big one. Penguins have massive spleens. Anyway, you need to know that an organ is a group of different tissues working together to achieve an overall goal.

PRESENTER 2: OK, gotcha. So we know what a tissue and an organ is. What about a system?

PRESENTER 1: A system is a group of organs that work together to do an overall task. So our nervous system is our brain and all our nerves, and that allows us to think, feel, move, dance and so on. Our digestive system allows us to eat delicious food, digest it; which means break it down and absorb it.

Speaking of which, there's a guy in France who once ate an entire plane by breaking it into tiny pieces, but I would not advise that at all.

PRESENTER 2: Is that true? That's astonishing! OK, I definitely wouldn't do that. All right, so a bit of a recap for us on this.

PRESENTER 1: To recap, cells make tissues, tissues make organs, and organs make systems. Some living things are made from a single cell. We call them unicellular — like a unicycle but with a cell. And they don't have to worry about any of this because they're just a cell. We're multicellular, which means loads of cells all together miraculously forming working human beings like ourselves.

It’s really important to know about different types of muscle cells because this allows us to understand how to best use them.

I'm Ruben Tabares, Strength and Conditioning Coach, Nutritionist, and Sports Therapist.

My job is to make people stronger, faster, to make them healthier.

Specialised cells are designed to carry out a particular role in the body, such as red blood cells, which are designed to carry oxygen.

Nerve cells help with the contraction or relaxation of muscles, depending on the specific job you need them to do.

The type of muscle that helps with digestion is called smooth muscle.

Cardiac muscle pumps blood around the body.

Skeletal muscle is made out of specialised skeletal muscle cells.

It’s not all about having big muscles. I personally like everyone I work with to have muscle fit for purpose.

There’s absolutely no difference between an elite-level sportsperson, such as Usain Bolt and a person who’s never really trained before. If they’re both running, they’re using the same muscles. The only difference is someone like Usain Bolt has trained his muscles over a longer period of time and when he pushes, he has more power in his muscles.

It’s really important to keep our muscles healthy because we want to be able to do the same things when we’re young as when we’re old. By having strong muscles, you ensure that as you get older, you can still run, walk up and down the stairs, and do all the other things you did when you were younger.

The best thing about my job is watching people achieve their goals. I do that with many different athletes across many different sports and that is for sure the best thing about my job.