Okay, with that, I want to go into some cell stuff, cytology. This is where it gets a little bit more palpable when we move away from the chemistry. At least that's what I think.
When we look at cytology, that's the study of cells. And a cell is the smallest independent unit of life. It's the basic unit of life.
So that's bacteria. There's no viruses. Viruses are not living things. The bacteria are. So they are you bacteria unicellular.
Lots of them are unicellular. We are multicellular. An adult human has 75 trillion cells. That's like that's what the bankers say we are too smart for you that's why so much money and then you realize they're just fooling us.
but that's at that money that's a that level question so the trillion is i googled it because i couldn't figure out what to do a stack of 200 no 100 bills is roughly an inch thick we stack them together and go from chicago to new york we get a we get a a trillion that's a lot of that's a lot of cells that we have in our body a lot look at all of them are red blood cells And then another look at that a hundred billion is in the nervous system. That's another place We have a lot of dense cell structure going on As when we look at the size of cells We got a micro is a measurement. That's a thousands of a millimeter a millimeter is like that's a centimeter That's a millimeter and thousands of that is like nothing That's how we measure that stuff. The largest is in the, look I made an arrow, ha, is in the anterior horn cell in the spinal cord. That's the spinal cord, that's like the stuff that goes from the brain down and then feet talks to the body so you cut that.
that through, when you cut that through, that's what you see. And so there are cells in there that are 135 microns, that's the largest we measured, and all of them, a human egg is 120, that's what we can see with the naked eye, is a human egg. And often a good question to know, not on my test, but some SATs or so is, how big is a red blood cell? So it's five to eight microns. It's tiny.
Five to eight thousandths of a milli of nothing already. We look at shape, also lots of different shapes. We have, oh, the smallest one is in the cerebellum, and that's in here.
That's the cerebellum cortex, not that you can figure. I don't know, that picture wasn't too descriptive, but this is descriptive. That's a human egg. So some of them are round, the whole thing is round.
Muscle cells are like spindly looking things that they can contract. So the shape dictates the function. The very, very fundamental concept again in anatomy and physiology. The shape, how something looks, dictates what it's going to do.
So you're not going to have a square and try to make a car out of it. And there's a wheel. It's not going to work. It's that simple.
I mean that simple. So when we look at things, we want to use that novel way of looking at it all the time. It's like, you know, that question. The why question in this sort of discussion is really important.
It's not the five year old why, why, why because you want a different outcome. It's the why, how does it work that way? Why is it that way?
And that brings us to the understanding of things. So the cells they start right they start originally mommy and daddy and boom we got one coming out but then how are you going to get from that one to like a red blood cells and nerve cell and also how are we going to do that so that's where we have those stem cells and then they differentiate they specialize in many different types of cells whatever we need. But the fundamentals are from the stem cells.
The stem cell, the mom and dad, GLA and all that, is where it comes from. That gives us all the stuff we need to make all of these things. So that goes back to the genes.
That's why it's so big. So many genes. So when we look at the basic cell structures we have, contain a fluid that is made out of a saline solution, that's aqueous means watery solution, that's saline means it's salty, it's like seawater more or less, and then we have proteins in it, and we call that together, that water broth with protein, we call that the silasol.
And then inside the cell we have a round structure generally, that's a nucleus. And around the cell we got this, we just talked about this phospholipobiol here. There's another picture of it, that's the cell membrane.
And then we got these things. And these things are little organs, they call them organelles. And they are structures inside the body, inside the cell that do all kinds of different things.
So like one makes the energy, that's the mitochondria. One has to figure out how to make protein. One will be helping with separating the cells.
One is the nucleus where we're going to hold the genetic material and all so forth. So let's go through some of them. Oh, well not yet. Also inside the cell, before we go to the organelles, this is actually a mitochondria right here, but around all of them and through the whole cell we have these, we have a cytoskeleton. So it's like bones inside the cell.
for the cell and so that's a supportive structure that's kind of a scaffolding type looking thing you know it's not like bones that way but it looks like it holds things together make sure the shape is there it also gives gives proteins and things to walk like pathways to walk around in the cell i mean that's that's some really goofy goofy stuff but it's really cool so that's a cell generic cell So we got the nucleus is a big thing, cell membranes around it, but we got these different organelles, we got this wobbly thing around the nucleus, we got to start working about that, talk about that. Then we got one that's like here looking thing that connects more to the cell membrane and export things and import things and so forth. So that's just when you study you can at some point then see do I remember what this is, do I know what this is and so forth. The cell membrane is the surrounding membrane. That's also known as the plasma membrane or plasma limma or elementary membrane also.
It's again a phospholipid bilayer and that makes it semi-permeable. That means water stuff can't go through except oil and oil stuff can't go through. That's half permeable.
Inside of it we have multiple things. We have channel proteins and a good channel protein that's right here right here that's a channel that that channel can open or close and if it's open it lets stuff in and out. If it's closed obviously it doesn't. So oily stuff can sort of go in and out on their own but watery type hydrophilic stuff cannot and so they need channels to have stuff go in and out. The other thing we have is pores and pores are smaller channels like they let water in and out for example as very small molecules or salt, sodium, potassium.
Those are more done with pores not channels. Channels more like glucose, larger molecules. And then well also what we have is we have receptor proteins and so for example we have a hormone this is a receptor protein. So let's say we have a hormone, let's say we have insulin that's gonna have to tell the cell on the inside to put, let some glucose in, open the glucose channel.
Actually the insulin is not a good example because that just attaches to the channel and lets it in. But we've got other things that cannot penetrate, that are hormones that can, hormones that cannot penetrate the cell membrane because they're watery type. So what they do is they have a receptor on the outside and then the receptor on the outside feeds into the inside and and does some change on the inside in the chemistry so it's a messenger so when you do a bio 20a you know talks about a second messenger system so that's interesting so some hormones have to act that way some hormones are just oily they just go in and out they make it easier oh this is the this is the picture that i like in terms of the saturated fats how these are like all stiffy And then we have the unsanitary fatty acids, how they make more room because they're kinked.
That's the physical structure, how you can see how it makes more room in the cell membrane. How then, nutrients, for example, you don't have a different reaction up here versus here where there's more space. So we can have different responses.
So the communication, the communication in a cell is the cell membrane. That's probably a very important concept too. It's not the nucleus, it's not like a brain thing.
The cell membrane It is what communicates. So it's very important that that cell membrane is in good shape. Not too much oxidative stress. So on top of the cell membrane we got that film and that film is known as a glycocalyx.
It has a sugary film, sort of a fuzziness on the outside and that's part of that communication system. One of the most important things about communicating for them is recognizing self from non-self. Is this my cell or is this not my cell?
Is this an invader or not? That becomes very important when you talk about the immune system. We'll talk about that in a little later and I guess we'll talk about it later. And then that brings me to the inside of the cell, the intracellular, intra means inside, intracellular structures with different functions.
So I think of organelles like, I think of a cell like a village. Then I'm like, what do we need in a village? village that is maintaining itself all we need we need we need we need an endoplasmic reticulum you know that right what a name right so an endoplasmic reticulum is yeah you gotta get used to these weird names is is a strong that comes right off of the nucleus and it's it's it's also membrane it's also phospholipid bilayer whatever is membraney and these are have phospholipid bilayer around it and so and so this structure here is making proteins and lipids so it makes it's a factory it's producing things and then it transports it around inside the cell some of this See like here outside is like smooth looking and then it has these little dots on it as we get closer.
The dots here are actually little ribosomes which is another type of organelle. And the ribosome is protein factory organelle so this is where we gonna get the DNA thing copied one of those single DNA not the double thing the single one comes out and feeds into here it's like a tape deck like the old tapes it feeds through the head reads whatever the music comes out well here it reads these nucleotide nucleotide nucleotide nucleotide what's the sequence and then on here it says well we need this amino acid and this amino acid and this amino acid put them next to one another and so essentially then the DNA becomes an amino acid assembly you know book that shows which amino acid after to reach amino acid for which protein and it has to coat that with nucleotides so that's going to be that kick that's going to be that trick how to do that so endoplasmic reticulum makes synthesizes protein and lipids and it it has a rough one they call it rough where these little ribosomes are on it that's where we make the proteins all the ribosomes itself and then where it's smoother that's where sort of lipid structures are made and then from there we have the next one that comes off of it so this is the ER they call it ER in short because endoplasmic reticulum is a long name and afterwards towards the outside towards the cell membrane more superficially we have another structure known as the Golgi apparatus that's also baggy but that picks up the creative material from the ER and packages it and exports it so that's a postal service as far as I'm concerned go to the press post office and then it travels inside the cell and then the other thing it does it export stuff but it's brilliant think about like you make you make the thing you bag it in a cell membrane you bring it to the next one that you ordered the Golgi the Golgi does some stuff and packages and all that and then it comes out of there cell membrane around it again you export you fuse the cell membrane with your whole cell cell membrane and export it that's right there so you reuse that phospholipid violator wherever we can use it it's so versatile if the body has some than they can use all the time that's great we don't need to make different pieces of it hey boy you know if you have an assembly line if you got the same piece you can use over and over you got multiple different ones you're gonna have at some point a bottleneck and you don't have to you can't make it cannot make it all so Golgi apparatus and a plasmid reticulum that brings us to the lysosomes the lysosomes are another spherical thing another layer a thing the phospholipopyl on the inside here now We have enzyme mixtures we have things that can destruct that can break down material they can ingest material and degrade them and so that that can be as simple as digest something but it would be as much as killing something as a matter of fact some cells they perish themselves they kill themselves and call it aldolysis and self-destruction they do that with their lives with the lysosomes so if you feel depressed you just remember there are some cells that perish for you they're selfless Lysosome. So very often like we take something in food, the food vacuole, they call that, that fuses with the lysosome and then we do some stuff with it, whatever we do, but then it can degrade. Next we have centrioles and centrioles are some really interesting, really beautiful when you actually look at their symmetry. It's very, very symmetrical.
And they help us, they're microtubules, they help us in cell division. What they actually do is when you look at here, there's one of these on this side. and one of these on this side, these things. You can't see that, but that's what's there.
And from there, you've got these green rays that come towards the midline. This is the cell right here, the whole cell. And on the midline, these blue things are actually the genetic material.
All the genes line up here because when you make two cells out of one cell, when you make cell division, you grow the cell, you grow the cell, and then at some point you've got to cope with the genetic material. And then you've got all these organelles and everything, but what's most important is that the genetic material appears in both daughter cells in an equal distribution and everything, because otherwise the daughter cell can't make protein, and that would be a problem. Then it can't survive. So this is how we organize that.
How are we going to, first in a cell division, we copy the genetic material, and then we have these centrals that make this organized way of lining all of them up in a midline. And then at the end, when it comes to the cell division, each side gets a set pulled towards it, and then we cleave the cell, and we have two cells. Why, but we'll slide on that.
You already did that, right? Yeah. Alright, good. Centrioles.
Lysosomes, centrioles, Golgi, and ER so forth. And that's the mitochondria. And that's that, yeah, where we make energy.
That's the powerhouse. We need energy. So, um... It's an interesting structure, looks like kidney bean type, and it has two walls, there's an inner and an outer elementary wall, an elementary membrane again.
And the inner one is very folded up, and what happens is, when we... We get glucose into the system, glucose is broken down into smaller molecules that are charged. And they go to one side of this wall, inside here.
And then you have a really, really high concentration on that one side. And at some point you open a pore. and a lot of these molecules flush in and the force of them flushing in together with oxygen makes ATP so it becomes like you know you think of a Niagara Falls so far making energy like the hydrodynamic something it comes like it's that force of these molecules that rush through that they can attach it at the phosphate under the ADP make ATP But that's for us what we need to know for sure here, because we need to talk about muscles and bones, that's much more important. We need to know the mitochondria is where we make ATP, energy powerhouse.
And that brings us to the nucleus. Yes, yes, question. Yeah, yeah, when we, when we, when we, yes, when we, the main, the easiest place to get energy from is a carbohydrate. So the glucose there gets cleaved off, and the glucose goes right into that, you know, that pathway that makes ATP.
When we have fats, fatty acids, and amino acids, we can also make energy out of those molecules, but it takes some energy to make them available like a glucose type available. So that's one reason why the Atkins diet is, you know, you're eating protein, it takes a body energy to make the molecule that make energy. So the yield is very different. But we can make energy from all those three micro molecules. Even though the glucose is using the energy, the fat is sort of the storing energy type-ish, and the protein is, amino acids are mostly the building blocks for structure, construction material in the body and so forth.
But we can make energy from it. So yeah, the body is very versatile. So good question, yeah, yeah, I didn't mention that. So that brings us to the nucleus, and that's a large sphere on the inside of the cell that houses our genes, and that's the hereditary characteristics. Most cells have a nucleus.
Some cells don't have a nucleus, like red blood cells don't have a nucleus. If they don't have a nucleus, that means they cannot divide. Red blood cells don't need to do that. They just need to carry oxygen.
That's all they need to do. That's all we worry about then. We've got lots of them.
So they get made somewhere else and then when they are done, they just get discarded and get taken apart from, you know, the spleen. get disassembled. Some have multiple nuclei like muscle cells. We look at a muscle, a muscle is like from here to here.
That's one muscle. That's a long cell. One muscle cell.
almost the entire length of a muscle. You have many muscle cells, like a cell is a strand, it's very small, very skinny, but it's long. And so when it's made, it starts as multiple cells that then fuse together and the nucleus is laid behind, so that's why we have more and more nucleus in the muscle cell. Not that important. The most important thing is if we know we need to have a nucleus to be able to divide.
No nucleus, no division. The nucleus is two elementary membranes filled with pores that is a boundary from the cytoplasm. So the nucleus is here and it's almost like a cell within a cell.
It's separated from the rest, it's protected. And then inside that we have another one called nucleolus I know why do they do that to us right it's like a Russian doll small small small and one more that but when we think about that makes sense because we need a place where we got to make the factories to make the protein because that's a protein in itself who's going to make that one the first one who's going to make the first one that then we can make it so that we need a place where that's happening and that's in the nucleus so they make their they call that the ribosomal rna i just read the word ribosome and then that says protein factory from the slide But that's why we have the nucleolus, because who's going to start out making protein? And that brings us to the next interesting part, the genes, the chromosomes. Chromosomes are the carriers of our hereditary characteristic. One gene, so we call this gene stuff we talk, that's information to make one protein.
So now we have a definition of a gene, so that's good. One gene for one protein. The chromosomes therefore are a cookbook of our proteins. We have 46 chromosomes, two sets of 22, mom and dad. That makes us a diploid.
We have copies of two. It's good to have copies. Once arrayed, we maybe have an order where we can use that. But if we only have half, one setter, they call them a haploid in that world.
We have about 30 to 40 thousand genes that are packed in a DNA double helix of about two meters in length. It's about this much in length. Every cell has this much in length of a strand in it.
That's a lot. But 30 to 40... Thousand think about that so that needs to be very well organized so the DNA double helix here is called around these protein things called histones that just coil things and then it's moved around then it's a strand and that strand is known as chromatine.
It's a spaghetti bowl, bowl of spaghetti. That's how it is when the cell is just moving around. And then it gets organized into these chromosomes when we have cell division.
And when we look at chromosome stuff, we read, we see these, right? When we read the table or so in college. This is college, right?
Yeah. I remember we had some on the wall. But then that's the chromosome, so we need that for mitosis.
Mitosis means cell division. The centromere or kinetochore is where the chromosomes come together. Right there. When we make a protein, what we basically need to do, we need to unwind everything back to being in a double helix and then take the double helix and unwind that and then we expose the nucleotides because the nucleotides are what's going to code for the protein.
So that's then that genetic code that we need to talk about. So we have all these, well we don't have all these, we have these four, we actually have five types of nucleotides, but we're four having DNA. So we got the A, T, the G, and the C. And they come like on a strand, here see here's the double helix, we unwind it and we'll take a little piece out of it.
So this is like a nucleotide here, blah blah blah. We take three of them. nucleotides and that three will code for one amino acid type. So that's how we can have genetic stuff, the nucleotide strands, the chromosome and make proteins out of it. So we take three of these letters and make, we need to make 20 different one of these amino acids.
We only have 20. So we're going to make these tables where we can say okay a guanine, an adenine and then cytosine make aspartic acid. That's an amino acid. You don't even know these amino acids, but that's what these are. You don't need to know the different ones, I need you to know that these are amino acids, and amino acids make proteins.
And so that's basically making protein right there. So three nucleotides that then will code into one amino acid, they call that a codon, a codon, or they also... call that a triplet because there's three nucleotides in the one amino acid so a triplet goes into one and that's when you see sometimes you know they have the genetic code GGA BBB that's what that is that's exactly what that is nucleotide sequences so when we take protein when we make protein basically we already did it now proteins about the work in the body we haven't talked about the muscle Hemoglobin. But what we need to do is we need to go and unwind the double the DNA double helix wherever that gene is that we want to copy that we want to make a protein out of. We need to make a copy out of that gene and now instead of a DNA the copy is called RNA.
So DNA when you look at the whole name it means deoxyribonucleic acid and RNA is not deoxy it's just ribonucleic acid. So that's the short version of it so for us what we need to know is the dna is that double helix thing in the nucleus that holds all the genes the rna rna actually i should say m rna rna stands for multiple things the one that this is is the m rna which is once we talk about the different types of rna when we use the word rna we mean basically the copy of the dna and then that copy that was a long discussion on that that copy then leaves the nucleus through one of the pores because we have a copy if it gets destroyed it's okay it's a copy we still have the original inside the original will not leave the nucleus and then that copy goes through the ribosomes and on a ribosomes we read these triplet things these codons and another is another this is also called an rna and again don't I don't know why they have the same word for these all these different things, but we have to just explain it once or so But we have then one RNA that can read the code on the wrong side and on the other side It knows which amino acid goes with that read and so it just you know They that way the strand goes through it and we get the right ones called down and they attach one amino acid after one amino Acid and at some point we have a protein like a hemoglobin No, I don't know how long a large DAP gene is. I shouldn't say that.
But it's not that long, the hemoglobin. So it's not that long. So before we do that one more time, there's a few more words on it.
I have this slide on RNA. And so the one that's the copy of the DNA is known as the messenger RNA, the mRNA. So that's the copy. So these are the nucleotides sticking out.
different ones, the four different ones. We also have the ribosome itself It also contains RNA, ribosomal RNA. That's the one that they make that in the nucleus.
So, RR, they say this, is RRNA? I think of that as the ribosome itself, since it's part of the ribosome. That way I keep them separate and I know which one's what.
And then they have another one to just, everything comes in threes, right? So they call that the transfer RNA or tRNA. And transfer that... That's the one that on one side can read the nucleotide, and on the other side understand the amino acid that is corresponding to it.
So that's actually the one that really in essence makes the protein then at the end, because it reads the mRNA. Confusing, huh? A lot of words now.
Yes, question. Good, good. Yeah, let's do it. You mean the tRNA has the ability to, on one side, it has nucleotides that correspond, you know, to the ones that come from the mRNA, from the DNA part, from the nucleus. These are always dead.
They don't go away. They just these are just readers and then the other side has amino acid and a protein is ultimately a chain of amino acids and So this is the one then that can read where are we on in this? the sequence and can bring the proper amino acid in and then make it put it onto the chain of the other amino acids that also happens so when we when you look at that that'll be this part here so this is just an honor visual has a couple more names in it that I need to put in.
This is one of the two main concepts for cell chapters. So if this is a little goofy, we'll do it again on Wednesday. Wait, today's Wednesday, on Monday. So again, the first step is we have that DNA and we need to make a copy of it.
So it's a double helix, so we unwind it. Look at that, I even put the enzyme in. See that word here? A-S-C?
It's an enzyme. I don't need to know that enzyme. But next time in study you come by, it's like, oh yeah, there's this enzyme. Oh yeah, it was there already. And so, but you need to know if it's an ASC, you know it's an enzyme.
That makes the mRNA. So the DNA gets uncoiled and you make a copy and the copy here is the blue strand that's the mRNA. And then that leaves the nucleus.
And so that copying process is known as transcription. You're transcribing. You go to the court and you have somebody sitting in the front of the transcriptionist. They're transcribing the spoken word into a written word. Again, it's still the DNA and the mRNA is the same language.
It's just a copy. So they call that transcription. Then that goes out of the nucleus, and then from there it goes into the ribosome.
And inside the ribosome, we feed these codons and these nucleotides in. And the tRNAs come in, these transfers. On one side, they carry an amino acid.
On the other side, they're reading all these codons, and that way we're going to make from nucleotides translated into an amino acid chain. So they call that translation. Because... That's like you go from Chinese to Spanish or from Swiss to German to English. That's what happens in my head sometimes or the other way.
But it's a different language. It's a totally different language. So they use the word translation for that describing that process because of that.
That all that makes protein. So this is exactly the same process. I just added the translation transcription verse to it. That way we do a few different levels on it. But again, you know, we got to keep it as simple as possible because the word, the body doesn't have these words.
We just need to give it these words to make sense of it. So as you know your essence inside of you, I'm a physical person, a kinesthetic. I touch people for a living and massage their muscles and crack their necks. And so I need to feel things.
And this is, I need to visualize. I feel it to visualize. So I close my eyes and say, okay, the double healing is online. So we make a copy of it. The copy goes out.
It gets fed into this other thing. And it reads it. It brings amino acids in. And then I can do the words. The process is more important.
The words. So that's why if you don't know the words and you're thinking you're just simply studying memorizing words, that's where we got to talk. That's why we'll see if these questions are a little helpful over time. All right, good.
Any questions to this so far? Yes. Mm-hmm.
Strands. Oh good question, yeah. Since you have complementary base pairs, you basically have one strand goes one direction and the other one is the same thing just go the other direction. It's the same sequence of nucleotides.
Because they're all complementary. So we don't need both strands to read. They're copies. So we only need one copy copied to make the protein. Hopefully it's not a damaged copy.
That'd be nice. But so we don't need both to make the protein. We only need one single one.
And then there's actually one more thing and I'm not sure where it's written down but if you think somewhere have you seen the word uracil? Uracil. Yeah, look at this here. The mRNA, instead of thiamine, it uses uracil. One more of those names.
So now you've got five letters. But the thing is this, if you see something like the genetic code, like this, like I think there's even a test question that's just like this, which of these is an RNA? and you see a line of words, letters. If there is a U in it, you always know it's an RNA.
DNA does not have the uracil, the U in it. I know, right? A U in it, it's RNA.
Well, if you're looking at the DNA-RNA thing, yeah, yeah, yeah. Well you can also go with, you know, if it's got the thymine in it, the T in it, then you know it's DNA. But the U is just easy to see.
And it's very specific. Good, look, if you're done with that, questions for now, we'll pick it up next week, but we can go to mitosis. You ready for that? Good, because we're starting to fall asleep, huh?
Cell division is very important for growth and cell renewal. Not all cells divide. Generally speaking, the more specialized cells are the less they most likely divide. So that goes for a lot of brain cells.
And then some cells don't divide if they don't have a nucleus. Before we divide a cell, which is the mitosis, we have to copy the DNA. And now, same thing, as making a copy for an RNA strand, we do the same thing, but now, we make both, we do copy both strands.
So now we unzip one, and copy both, and end up with two of the whole strand thing. Not RNA, now it's two DNAs. But it's a copy question.
And then once we copy that thing, the next question, the real mitosis question is, how the heck are we going to make that genetic material end up in both daughter cells? How are we not going to have two-thirds of it in one side and one-third in the other? That's not going to work. It's okay if we don't have a full mitochondria in both. I mean, one less in one side, we can just make it all in one.
That's fine, but the genetics, we can't change that. And so we have this process, these phases that describe that process. And we have a prophase, a metaphase, an anaphase, and a telophase. So they name these things. They name the prophase, which means before, metaphase means in between, and anaphase means upward.
I don't know where that comes from. And the telophase means an end goal. So there's some words why they use those words.
But so basically now what you have is you've got a spaghetti soup. of these chromosomes and they become visible and get to like this where we can actually see them in these chromosome type structures and the nucleus also disappears and that gets us then to the next phase the metaphase which is where the centrioles go to the corners and make these interesting spindles these are like real free They track. These are like mobile roads, you can think of that.
So they reach in to an area in the center of this cell called the equator. The equatorial plane in the middle where the chromosomes attach and line up by those centrometers where the legs cross. In a video where that is actually visualized, it's called kinetochore. So there's different names for this.
But anyway, from there then... When everything's already, we're gonna have this anaphase, which is when the chromosomes have separate and they literally, you see it in a video, they get pulled to one side by molecules that pull them like on a rope and walk on these, they call them asters, but I think of them like roads, basically tracks. And then they go to each side of the cell, and then they split.
The telophase is basically we make a nucleus again and we sort of uncoil them and recreate the situation. So it's really basically the process of how do we split these chromosomes apart. So you go through those a few times.
Sensible? Okay, after. It makes sense?
I know, after protein synthesis, that's no thing, right? Easy peasy. And then we also have to briefly talk about meiosis and that's a reduction, that's a reduction or maturation division. We use that when we make the sperm and the eggs. So how the heck we gonna get from 46 to 23?
Because if you got a sperm and an egg come together, you can't have 46 in each side. You're gonna be way overdoing it. So you're gonna only accomplish 23 from each side, from mom and dad.
And then combine and make 46. And so you gotta figure out how we're gonna get from the regular 46 down to 23. So basically what we're gonna do, more or less, is we're gonna have like two divisions. The first is like mitosis. We copy stuff and it gets distributed to two daughter cells. Except in this situation, some fragments cross over, which gives us diversity.
That's why his siblings don't know what to say. For sure don't act the same. And then the second one is where you make a cell division without copying the DNA and you end up with 23 because you split those in half so that's 23. So that's basically what meiosis is about. So mitosis is for all body cells meiosis is only for the gametes, only for the sex cells, the sperm and the eggs.
And then we leave that alone because to finish up we gotta talk about transports. Substances need to move in and out of the cell. Yeah that's very important.
We have two types of transport. We have active transport, we have passive transport. Passive transport means it just happens.
So that could mean concentration distributes, just things just evolve like put a sugar cube in water and swirl it around, that stuff dissolves in the water. That doesn't need any energy, it just happens. Active transform means it needs energy, ATP.
Like if you would want to take your bike and come up the hill, you would have to really put a lot of energy out to go up the hill. So very often we use this when we have to push molecules against the concentration, against the... strong concentration that's already there. So it's like we have to push it into something that it naturally doesn't want to go to and that's a matter of concentration.
Have you ever been into Tokyo or something? Probably not, right? They have pushers, they have pushers there. They fill these subways to train so much that before the doors close they have these people that push them in before the doors can close.
And so the concentration of people in that train is really heavy. So when those doors open, they all fall out. And so that's that concentration question.
So if you like stuff a lot of sodium ions on one side of a cell membrane, and then all of a sudden you open a channel, everything wants to come in. They all want to go to one side where there's nothing there. So molecules want to move from a higher concentration to a lower concentration naturally without losing energy.
And we make use of that in the ball. But that's the active and passive question. So are you going with the concentration gradient or against the concentration gradient? concentration is it using energy or not and then we have a few different types so we have passive transport simple diffusion that means the sugar molecules you go from higher concentration molecules naturally to a lower concentration why molecules want to be balanced out they want to eat out they want to disperse and intermingle we kind of know that intuitively but chemically we still have a concept with that and then we have more diffusion but this time it's not just free and simple and in the show sugary molecules, now it's facilitated. So this is a place where you have, let's say, you have a cell membrane with a protein channel in it that's gonna let the glucose interact.
So when that protein channel is open, that glucose channel is open, it's gonna go in and it's gonna distribute according to concentration gradient. So if there's more sugar on the outside in the bloodstream and the doors are open, it's gonna. gonna bring it all in because the concentration is high up here and that's where the cells even smart to sell that's where there's an exchange reaction so glucose comes in it active is a phosphate and so then the concentration looks different because it's a glucose phosphate that's a different molecule so it always appears like when these are open there's always more sugar in the bloodstream that inside of the cells it always comes in so it's kind of smart for me to follow your step so those are paths Once that channel is open, it just happens.
You don't have to do no energy, nothing. We also then have a couple more passives. One is easy.
One is filtration. One is filtration. that's like you make coffee so water is dissolved particles are pushed through a membrane pore system separating particles from the solution so this has to do is how how thick are the pores in the filter that don't let the coffee grind go into the water so do that so it's not you know how what stays behind they use that in the kidneys the blood is filtered through a membrane like slits that only that certain things in and not all of it because that's filtration but But then we got osmosis Jones. Osmosis is the diffusion of water between two compartments separated by a semipermanent membrane, not letting solutes pass.
In this situation, water will move to create an even concentration of the solutes in both compartments. That gets a little more complicated. So now what we have is we have a beaker with two parts, and we have this membrane here that does not let the particles go through. Only water can go through. The desire of this situation is that both sides have an equal distribution of the particles.
That's just what nature wants. and so now though because we can't move the particles the book is smart now the water moves not the particles that's osmosis we can use this in the body greatly like you have blood the heart pumps the blood and it goes into the blood vessels it goes into the tissues it leaks out how's it gonna get back into the bloodstream how are you gonna get it black into the veins we let some molecules stay behind in the blood then they suck the blood back in so it's a suction you can think of you can think of these particles become a suction of water thing and you visualize that this have you cut a tomato put salt on top Oh, too bad for you. That's good for your prostate, brother. Anyway, lycopene, lycopene. No, but if you do that, you have first a little salt kernel, and all of a sudden it's a little drop of water on there, right?
The water, the salt... pulls water towards it. So in the body, sodium, salt is brilliant to pull water out towards it and you see that in the tomato.
So we have for example a situation where in the kidneys where we have sodium gets extracted from one side and water follows it. So we use that concept. So we use osmosis to have liquids move around in the body and one of the main ones is water, of course.
Now we can then we get to the active one. So now we need energy. So we're going to go against the concentration gradient So the biggest ones in there that we use all over in the body are these pumps and these pumps They what they do is they act effectively carry small molecules against the concentration gradient that establish a concentration gradient for later use. So this is brilliant.
So now what we do is, this is a nerve impulse for example. So in a nerve impulse we got, this is a cell membrane. So now we got these pumps, they're right there pumping.
The pump carries three sodiums to the outside and two potassiums to the inside. It's one of the pumps, the sodium potassium. We need those two ions to make an Irving pump.
And what happens is with this always working you create a high high high heavy concentration. There's a big N-A. Sodium is N-A on the outside of the cell and very little on the inside.
Now you want to make an Irving pump. All you gotta do is you gotta make a gate and open the gate and let sodium come in. And the concentration created is so great that this sodium wants to come in all at once.
It's so powerful. And what has sodium on it? It's got a charge.
And that's how we make electricity move around in the body. So the electrical charge goes all the way from the outside and gets sucked into the inside of the cell. And that moves, that's electricity moving. And so the electricity ends up being a passive event because the active pump establishes that high concentration gradient.
So often, ATP needing processes like a pump takes a lot more time than something that just happens naturally, like, you know, you're falling off, you know, jumping down, gravity pulls you down real fast. It's much harder to walk uphill before you can jump down again. Not the best example.
Maybe we'll use the example of like you're taking your bike off. Next month we should all come to school with a bike. See how long it takes us to go uphill?
Lots of ATP. But once we go down it's like, hmm, make sure these wheels stay on, huh? It's like an explosion can happen.
Nerve impulse is the same way. It's a really steep hill. We'll talk about that some more later.
But this I hope is the last. Yes, thank the Lord. The cells that more active processes are bigger stuff like eating, eating stuff.
So when we use the word endocytosis that means some substances get brought into the cell. Endo, the word endo means bringing things into the cell. The word exo is for exit. Exit is get out of here.
So that leaves the cell. Exocytosis leaves the cell. So there's our substance.
So when something like a food particle comes in, often what happens is, look at this, it's pretty, right? It's pretty. We have food particles coming into the cell and the cell says, oh, look at that, we can bring this in. So it pinches off some cell membrane and it has the food particles in cell membrane. Now all we need to do is we're going to get that lysosome and we fuse the lysosome together and make a whatever...
food-vacuum-lysosome combination and then the food is being digested from the lysosome right inside of it. Or when we want to bring, exit something out of the cell, like we made something and want to let it go, we talked about that with the Golgi apparatus, we just fuse this membrane with the cell membrane and the contents can go out. Pretty simple.
Maybe eat. The cell eats something that's known as phagocytosis. Cellular eating is phage, phage is eating. P-H-A is booboo, that stuff is eating, phage.
Peno-cytosis means cellular drinking. And I remember that because there is pino-grigio and pino-noir, and I like those too. And so pino-cytosis is drinking.
So that, you know, mnemonics gotta be a little silly and then it works. Phagocytosis eating, penocytosis drinking. And that basically talks about this processing. Whoo! Oh, that was a walk.
How are you doing? Hanging in there? Any questions come up right on top?
No? Yes? Well, that's a no.