BTEC Applied Science Unit 1 Biology Cells. We need to know quite a bit about cells. Now, cells are the building blocks of living things.
A living thing is an organism and cells are, if you like, supposedly the simplest parts. Lots of different, well, lots of cells of the same type of cell makes up a tissue. Organs could be made up of different types of tissue. A system such as your digestive system is made up of organs and then all these systems together makes the organism.
But the building blocks are the cells. They are the bricks that we are made out of. Cells.
This looks a bit frightening at first. We're going to go through all the different pieces. What do they do?
What are they called? What do they do? This is a typical structure of an animal cell. And inside the cell...
We see these things called organelles. These organelles which do different jobs. So as I said, what are they called and what do they do?
The plasma membrane. This is like, if you imagine the cell as being like a city, this is the wall of the city and there are gates and things can get in and out. So it protects the cell from its surroundings.
It allows substances in and out like carbon dioxide and oxygen and food and things like that. Okay, the plasma membrane like the city walls. Cytoplasm is the kind of liquidy jelly that fills the cell. It's got lots of stuff dissolved in it and there's lots of chemical reactions happening in it. That's the cytoplasm.
The nucleus The nucleus of the cell. If the cell is like a city, then the nucleus is the town hall. It's where all the decisions are made.
It's surrounded by a double membrane. It has pores, nuclear pores, so that stuff can get in and out. That is the nucleus of the cell, the control centre.
In the middle of the nucleus, there's a thing called the nucleolus. It's a region of dense DNA. And this is where ribosomes are made, which we will talk about shortly.
I think of the nucleolus as the library. OK, lots and lots of books, mostly recipe books, by the way. So the nucleus is the town hall. And then the nucleolus inside the nucleus is like a library. Ribosomes.
Now, ribosomes make... proteins they're like little factories okay your dna contains the instructions to needed to make all the proteins that make you up and ribosomes are given the job to make a particular protein and they make it so ribosomes make proteins and the instructions to make a particular protein is in your dna okay so ribosomes make proteins uh in a eukaryotic cell such as an animal cell there are the ribosomes are called 80s. In a prokaryotic cell we're going to talk about these in another video. The ribosomes are simpler they're called 70s ribosomes. Rough endoplasmic rectilium.
These are flattened sacs with a membrane covered in ribosomes. Okay, so lots large surface area all covered with ribosomes making lots and lots of protein This is rough endoplasmic reticulum There's another one smooth endoplasmic reticulum And these are kind of tube things and this is where lipids are made Lipids are kind of molecules like fats Okay, so rough endoplasmic reticulum and smooth endoplasmic reticulum. Vesicles, these are like little taxis that carry stuff around the place.
Okay, it's like a little ball and it's a small membrane-bound sack for storing and transporting substances in the cell. So for carrying stuff around in the cell, these little balls, these Taxis, called vesicles, carry stuff around. The Golgi apparatus. This modifies proteins and packages them in vesicles for transport.
It's a bit like the post office. Stuff goes to the post office and they do stuff to it. Maybe they change it, they add bits to it, whatever. Then they put it in packages, which are the vesicles, and then they send them off.
If you look at the diagram and the photograph, it's a very distinctive looking thing. It's called the Golgi apparatus. It's like the post office.
Lysosomes. These are the rubbish collectors. Lysosomes. Enclosed by a single membrane, they contain digestive enzymes.
They destroy old organelles and pathogens. Pathogens are things which can cause disease. So they collect rubbish and then the enzymes inside them break it down. OK, lysosomes.
Centrioles, they're involved in cell division when the cell splits. OK, mitosis usually. Two hollow tubes at right angles to each other are the centrioles. Looks to me like a couple of bits of macaroni to me. the centrioles. They make the spindle in cell division.
They go to either side of the cell and then all your chromosomes line up and then all kind of crazy things happen which we don't need to know about. But they're involved in cell division, the centrioles. Mitochondria, very important. This is where respiration happens. A chemical called ATP, which is the kind of the chemical energy used by the cell where ATP, I believe it's adenosine triphosphate, is produced.
They're like the little power stations in the cell. They are surrounded by a double membrane, the inner membrane, lots of folds to give it a large surface area, and then the central area contains a jelly called the matrix and all the chemical reactions happen which produce ATP. contains ribosomes and DNA. Okay, interestingly, it is interesting that the ribosomes in mitochondria are 70S. Everywhere else in an animal cell, they're 80S, but in a mitochondria, they're 70S, which suggests something happened in our evolution.
That may be some kind of prokaryotic cells formed a symbiotic relationship. and became mitochondria. Here are some electron micrographs.
You should be able to identify these. Look at these pictures. Do you recognize what they are?
If you don't, go back and look through the video again. Okay, I will show you what they are in two seconds. They are, there you go.